Friday Flownex Tech Tips #13

Parameter Sheet Tricks

It’s Friday and time for the 13th Tech tip! Today we are going to go over some simple parameter sheet tricks and best practices. Parameter sheets are incredibly useful for running many different design or operation analyses. Let’s go over how best to utilize their functionality. In this example we’re working in Flownex version 8.12.7.4334

Parameter Sheet Setup

Probably the most critical thing to know when working with Parameter Sheets in Flownex is to make our edits through the setup interface. This is where we define the connection between Flownex and the worksheet.

As we recall, adding either inputs or results to our parameter sheet is as simple as dragging and dropping them into the different columns.

Renaming Parameter Columns

We may find that we’d like a more descriptive name of an input or result parameter than simply
“Pressure” or “Temperature”. We can rename the columns and this must be done via the parameter table setup. If we were to change the name in the worksheet it will be overwritten by the setup when the model is solved.

Rearranging Parameters

We may decide after creating a parameter table that we need to go back in and add a new column between existing input or result parameters. This should be done, again, through the setup. We will add our new parameter to the first open column and then move it within the setup.

*Important Note: Cell references in Excel are explicit in parameter sheets. If we are performing calculations in the parameter sheet using cell references and we rearrange columns these formulas will need to be updated.

Bonus Tip!

Friday Flownex Tech Tips #12

Sizing Pumps and Manually Specifying a Pump Curve in Flownex

As a System Engineer you may not always already have equipment decided on for your particular network. Flownex makes it easy to start from scratch and will help determine the equipment necessary to meet the flow or process requirements. In today’s tip we’ll go over how to size a pump using the basic centrifugal pump component and how to manually enter pump curve data. We are using Flownex version 8.12.7.4334

Sizing a Pump

In our example scenario let us pretend we are sizing a pump for a cooling water circuit. We are tasked with finding a pump which will deliver water at a rate of 1 kg/s to the heat exchanger. We know our upstream and downstream boundary conditions as well as the heat added at the exchanger and the speed at which we will be operating the pump.

Choose the appropriate flow component

There are a few different pumps available in Flownex:

Basic Centrifugal Pump: Used when we do not have a pump chart available, particularly useful when sizing a pump.

Fan or Pump: Used when a pump chart is available for modeling either compressible or incompressible flows.

Positive Displacement Pump: Used for modeling rotary and reciprocating pumps where the fluid is incompressible, non-Newtonian, or a slurry.

Variable Speed Pump: Similar to the Fan or Pump but with the ability to interpolate between fan/pump curves for different speeds of rotation.

In this case we’d choose the Basic Centrifugal Pump. This is found in the component pane under Turbos and Pumps. Since we only know the RPM we can enter it in the inputs under Speed at BEP:

Recall we don’t know what the design of the pump will be. Since all we know is that the mass flow rate needs to be 1 kg/s we will check the box for fixed mass flow and then select to change design to target our desired flowrate.

Once we hit solve our pump design inputs will be populated such that our desired mass flow rate is achieved. We can cross-reference these values with available pumps to choose the appropriate component for our network!

Specifying a Pump Curve

If we already know which pump we are using, or perhaps are trying to decide between several available pumps, we may need to add these pump curves to Flownex. To add a pump curve we will navigate to the Charts and Lookup Tables pane > Project Database > Flow Solver > Turbos and Pumps. In this scenario we are looking at a single speed pump so we will right-click on Pump and Fan Charts and Add a Category.

We can name our category whatever is appropriate and then right-click on the newly created category to add our own pump chart.

To edit the newly created pump chart we can either double-click on it or right-click and select edit. Now we simply specify the Reference Density and then fill out the table with the relevant data points. To speed things along we can copy and paste a table of data points from excel or whatever source we get this curve from. Don’t forget to check your units!

Bonus Tip!

Friday Flownex Tech Tips #11

How to use Flow Path Graphs and Increment Plots in Flownex

Flow Path Graphs and Increment Plots can be incredibly useful visualization tools to see how a simulation result varies as a function of length along the axial flow path and to see a higher fidelity result for a single flow component. Use these in Flownex to up your reporting game! In this demo we are using Flownex version 8.12.7.4334

Creating a Flow Path

A flow path is any continuous series of flow elements and can be created by clicking “Flow Paths” in the results ribbon. Once we’ve created our new flow path we define it by choosing our start and end nodes.

Another, simpler, method is to simply drag and drop the nodes onto the flow path start and end point:

If we have a branched network we can add an intermediate node or flow component to our flow path to ensure the correct path is captured in the graph:

Insert a Flow Path Graph

The Flow Path Graph is in the component pane under visualization > graphs. Once the graph is added to the canvas we simply need to drag and drop our newly created flow path onto the graph and choose the characteristic we are interested in plotting. We will need to drag and drop the flow path for each characteristic we would like plotted.

How to create Increment Plots

You may have noticed in the previous images that there were many data points on the graphs for each of our flow components. This is because we had each pipe modeled as 25 increments. When we add increments to our flow components Flownex will treat each component as if it were split up that number of increments – solving the conservation equations for each increment rather than once over the entire component. This is helpful when modeling long pipes, capturing pressure waves, or determining exactly where a phase change may happen. A good way to think about this is that it is essentially the same as refining a mesh in a typical finite element analysis.

There is another plot in Flownex we can use for a single flow component that has been incremented. The increment plot is located in the components pane under Visualization > Graphs > Increment Plots. If we were, for example, trying to plot the inside surface temperature of our first pipe in this example network we could use an increment plot to see what is going on.

To create an increment plot we simply drag and drop the plot onto the canvas. We can either selectively drag results from individual increments or multi-select many increments and drag the desired variable onto the graph. Note that since there is a tie of each increment parameter separately there may be some delay if we are multiselecting a very large number of increments.

Bonus Tips!

  • We can use a Flow Path graph for a single component to avoid having to multi-select increments.
  • To create a graph on its own page instead of floating on the canvas go to the Project Explorer pane on the left side of the GUI, select Graphs, then right-click on the Graphs Folder and select Add Graph Page and choose your desired type of plot.

Friday Flownex Tech Tips #10

Rotor-Rotor and Rotor-Stator Cavities

Happy Friday! In today’s tech tip we’ll introduce the rotating components library and demonstrate how to utilize the cavity drawing tool for rotor-stator cavities which can be a huge time-saver when building secondary flow networks. We are working with Flownex version 8.12.7.4334.

Rotating Components

One common implementation of rotating components in Flownex that I see is for modeling secondary flow networks for gas turbines. These flow paths are also sometimes called secondary air systems. What this refers to is the flowpath separate from the primary flowpath (Secondary, get it?). This is flow used to cool equipment, shrouds, discs, vanes, and to provide buffering for the seals to the oil system.

https://flownex.com/industries/gas-turbines/

Flownex has a whole library of rotating components that come in handy when building these secondary flow networks. These are well documented in the Flownex help manuals if you’d like to read up on technical specification, inputs, results, and theory.

  • Custom Vortex
    • A custom vortex is used when velocity profile is between that of a forced vortex and free vortex.
  • Forced Vortex
    • In a forced vortex the fluid moves similar to a solid body with constant angular velocity.
  • Free Vortex
    • Free vortex swirl is calculated using mass flow rate average of the incoming swirl streams, swirl is constant over the radius; usually used for rotating fluid in an open cavity.
  • Labyrinth Seal
    • Used for modeling axial and radial straight and staggered seals.
  • Rotating Annular Gap
    • Used to model flow through an annulus with the inner or outer cylinder rotating.
  • Rotating Channel
    • Used for flow inside channels in rotating discs and blades.
  • Rotating Nozzle
    • Similar to a stationary nozzle where there is a discharge coefficient as a function of the inlet type.
  • Rotor-Rotor Cavity
    • Used when calculating swirl ratio from moment balance on the the rotor surfaces, bolt heads, and flows.
  • Rotor-Stator Cavity
    • Used when calculating swirl ratio from moment balance on the the rotor and stator surfaces, bolt heads, and flows.

Cavity Drawing Tool

Now we get to the nitty gritty of todays tip; how to utilize the cavity drawing tool. When we use either a Rotor-Rotor component or a Rotor-Stator component there are two options for specifying the surface geometry. We can either model as pure radial disks, or as a complex surface specification.

We can use the complex surface specification option to model a rotor-stator cavity like in the cross-section below. When using this option we will need to get a cross-section like this from CAD or from a scaled technical schematic.

To specify this surface geometry we will click the radio button next to surface geometry and add our image to the project. For a refresher on adding an image to your project check out the blog post on adding a background image.

Reference Measurements

We will first need to specify our reference axial and radial coordinates. This is done by dragging the red and blue boxes to known locations on the cross section and entering in the values in our desired units.

Surface Geometry

Now that we have specified the reference measurements we can define our rotor and stator surface geometries. This can be done in the Rotor Surface Geometry ribbon and the Stator Surface Geometry ribbon. The mode in the top right of the GUI lets us know if we are adding points, moving points, or deleting points. To add points we will click and drag from the previous point.

You’ll notice the inner and outer radius fields are automatically updated. This can be a good way to sanity check against known measurements or against CAD. We will need to do the same thing for the stator surface geometry.

Bolts

If there are rotor or stator bolts they may be added in their respective ribbons. The blue lines we see in these images represent the limits of the rotor or stator surface. If bolts are added we will need to click Bolt Details at the bottom of the window and add bolt geometry. The radius fraction is populated automatically and the other inputs will need to be updated as needed by the engineer.

Cavity Shroud

If we need to model the cavity shroud this can be done in the shroud ribbon. In our demonstration today the shroud is included in the rotor and stator surface geometries. For this case we can de-select specify shroud width.

Gap Width

Next we must specify the gap width. To understand what the appropriate width to specify we must dive a little bit into the theory.

Flow regimes for rotor-stator cavity flow can be classified by the following image:

“G” being the gap width ratio (s/a where s is the gap width and a is the outer radius of the cavity) and Re is the Reynolds number for cavity flow. Essentially there are four regimes which are determined by the Reynolds number and gap ratio.

Flownex uses correlations from Haaser et. al (1987) and Daily and Nece (1960) to calculate the required moments produced by the rotor or stator on the fluid within the cavity. Haaser et al. is valid for Regime IV whereas Daily and Nece is valid for 0.0127<=s/a<=0.217 and 1000<=Re<=1e7. It is suggested to use Haaser when the flow is in Regime IV and Daily and Nece when the flow is within the other regions.

I hope I haven’t lost you.

So, for complex geometry (not just two flat surfaces) it is recommended to use the smallest gap width first and calculate the disc Reynolds number. Using the smallest gap width gives you the smallest gap width ratio which will lower the point at which your fluid is in the flow regimes graph above. Now check in what region you are. If your Reynolds number is high enough to be in region IV, and while using the smallest gap width your are still in region IV then it is safe to say that your entire flow will be valid when using Haaser. If this is true, you can then use the smallest gap width because the correlations of Haaser is not dependent on gap width. Using the minimum gap width essentially allows you to make sure that your entire flow is within regime IV. When you have used the smallest gap but see that your gap width ratio and/or Reynolds number leaves you in a different regime (I,II or III), we will then suggest that you calculate the moments using Daily and Nece.

To summarize, start with the smallest gap width and determine the Flow Regime:

If we are in region IV for the smallest gap width then we can leave the gap width as originally specified. If we were in any other region we should change our gap width to be an average:

Don’t forget to specify the correct correlation in the inputs for your rotor stator cavity as well. Big thanks to Leander Kleyn at Flownex for helping me understand the theory behind the gap width!

Discretization of the Cavity

Lastly, we need to assign the discretization of the model. This can be thought of as sort of refining the mesh of the cavity. We can specify more or less increments and can drag the increments around to be sure to capture changing geometry.

There you have it! A complex surface specification of a rotor-stator cavity using the cavity drawing tool in Flownex!

Friday Flownex Tech Tips #8

How to Setup an External Shared Database in Flownex

Hi Folks! Another short and simple tech tip this week; How to set up an external shared database in Flownex. When working as part of a team it makes sense to share resources. Once one person builds a custom component or defines a complex fluid we want to share that with everyone in our organization. Today I will show you how to create and maintain a shared database. For todays example we are working in Flownex version 8.12.7.4334

Creating the Database

Start by opening up Flownex – it can be a new project or any existing project. On the right side of the GUI we’ll want to navigate to the Components pane. At the top of the pane you’ll see a variety of buttons. Depending on your installation the buttons you see may be different than the ones in the visual below. To create a new database we’ll want to click the Create Database icon.

Then we’ll want to navigate to a shared network location and pick an appropriate folder that will be accessible to others in our organization. I would encourage keeping the directory name as short as possible (I.E. a top level location) so that there is no concern for a deep database hitting windows character limit.

Once we have chosen a location and clicked OK we will see our shared database in both the Components pane and in the Charts and Lookup Tables pane. We’ll need to right-click on the newly created shared database and create a New Library in which we will place our shared components. Creating multiple libraries can be useful when grouping similar components or to discretize between different groups in the organization which are using Flownex.

Adding components to an External Database

To add custom components to our external database we simply drag and drop them from our project database. If you want to learn how to create a custom compound component please reference our previous blog post on this topic here. Choosing “Copy” will create a copy of the component in the shared database, choosing “Move” will move the component to the shared database and any references to that component in the project will now reference the component from the external database.

Adding a fluid to an External Database

To add a custom fluid to our external database the process is very similar to the procedure for the custom compound component. The only difference is that we want to do this drag and drop action within the Charts and Lookup Tables pane instead of the Components pane. If you need a refresher on creating or importing custom fluids here is a blog post on that topic!

Connecting to an External Database

Once a user has created a shared database it is now possible for other users to connect to that database. the process of connecting to an external database is quite simple. On the Components pane we will again look at the buttons near the top. We will want to click the Connect Database icon and then navigate to the shared location of the external database. Once there we will find the database configuration file, .dbcfg. We should select this file and click OK. You are now connected to the shared database!

Bonus Tips!

  • To lock an external database to avoid unintentional editing you can right-click on the database in Flownex and select “Lock Database”.
  • If you need to migrate the database to another location on your server you can copy the entirety of the folder and move it. Users will simply need to follow the same procedure of connecting to an external database the next time they open Flownex.
  • Special Note: If sending a network to someone external to your organization it is important to note that components or references from external databases will not be included by default. These components or charts will need to be copied to the project database and then the shared database will need to be disconnected before archiving the project for transfer. A second option would be to share the database itself.

Friday Flownex Tech Tips #7

Using Views to bridge networks across multiple pages

When building our networks it may be necessary to utilize multiple pages for a single network. This could be simply because our network is large and complex, or because it simply makes sense to keep certain branches or processes separate. In this tech tip we will show how to use “views” to continue networks across multiple pages. For this example we are using Flownex version 8.12.7.4334.

Views

In Flownex the way that we continue networks across pages or even just jumping across portions of the same page is through the use of “views”. To create a view we right-click on the component we’d like to use as our bridge and select copy. Then navigate to where we’d like to continue our network and right-click, “paste view”.

Note that this is not really a “copy” of the previous node; it is another instance of the exact same node. I personally recommend using nodes for views over flow components so that they are less likely to be mistaken as separate components.

Regarding views

A couple of things to note regarding view components. First, you’ll notice the floating “V” to the left of the component. This indicates that the component is a view. It’s a good idea to leave this layer on – if for some reason you cannot see the “V” it can be turned on under the view ribbon:

Secondly, to find out where the views are located in your network the simplest way to jump between them is to right-click on an existing view and select the “views” option. Here you can navigate to any other views by simply clicking on them. Note that you are not limited to only two instances of a node (two views). There could be many instances across many pages.

Common uses of views could be to connect networks built by different engineers, connecting different subsystems that make up a larger network, or even capturing 3D network layouts by building a portion of the network in the x-y plane and using a view to connect to part of the network built in the z-y plane.

Friday Flownex Tech Tips #5

Custom Result Layers!

The result layers in Flownex have evolved quite a bit over the last few iterations of the code. Although we might typically associate color-gradient results more with 3D CFD, it does have a place in 1D system modeling. Taking advantage of results layers in Flownex can give a very quick understanding of what is going on with our system, and, with a little customization, can be incredibly powerful as an addition to our design and analysis toolbelt. In this post I am using Flownex version 8.12.7.4334.

How to create a result layer

To create a custom result layer we must navigate to the results ribbon and select result layer setup.

First we want to right-click in the Result Layers window and add a new result layer.

There are two options to add the schema for our result layer. The first is to right-click on the Selected Result Layer Schemas and add either a specific or generic schema. The second, and my PREFERRED, method is to simply drag and drop results from components on the canvas into this window:

Note that I want to multi-select any component types which will be included in this result layer. This could be any flow components which share a common result such as “quality”. I also convert to generic because I want the result layer to apply to all pipes, not just the pipe I initially drag and drop the property from.

Defining the custom result layer

In this example I have a two-phase water network with a cold external temperature. I want to create a result layer to quickly see if the water is in the gas phase, liquid phase, or somewhere in-between. The problem I have been tasked with solving is ensuring that the water never condenses. I will need to determine where we may need to add additional heat flux to the network.

We can use the Quality result property to determine the phase of our fluid. Quality < 0 indicates fully liquid, quality between 0 and 1 indicates liquid/gas mixture, greater than 1 indicates fully vapor.

To make this work as intended I can set up a gradient with three increments going from -1 to 2. The idea being the lowest increment would encompass -1 to 0, middle increment would be 0 to 1, and the top increment would be 1 to 2. For the gradient mode I made sure to pick <-[MinValue, MaxValue]-> so that the max and min increments would extend past the specified range.

As we apply this to our network we can easily see that we do, in fact, have a phase change from gas at the inlet, to mixture in the second two component, to fully liquid near the outlet.

I may decide to add a heater to our outlet pipe and perhaps a thicker insulative layer to all three to attempt to keep the water in gas phase throughout the system.

Bonus Tip!

  • Result layers can also be super handy when troubleshooting to quickly identify large pressure differentials, choking points, or other outlying fluid properties.

Flownex Friday Tech Tips #4

How to make a great compound component!

Compound components make it easy and efficient to reuse the same collection of components over and over throughout your models. In this post I’ll be going over the basics of making a user-friendly and aesthetically pleasing compound component. In this example I am working in Flownex Version 8.12.7.4334

How to create a compound component

To create a compound component we must first create a local library in the project database. This can be done by right-clicking on the project database in the components pane and select “New Library”.

We can name our new library and choose a picture if desired:

To create our compound component we just need to right-click on the new library and select “New Compound Item”

To build our compound component we’ll use the “edit” function on the compound component. In this example I am building a Lohm resistor component. It’s a good idea to test my component on a separate page to make sure scripts interact as expected and validate results against some given test cases.

Let’s make it functional!

To define the inputs and results we’d like to expose to the user we right-click on the new compound component in the library and select “component setup”.

To add inputs and results we need to navigate to the Compound Setup ribbon and then simply drag and drop inputs and results into the Selected Properties window. Note that we can even grab whole categories of inputs or results to save time!

Now those inputs and results will appear to the user when they add this compound component to their canvas!

Let’s make it pretty!

To make our component more aesthetically appealing let’s replace the boring default icon with one more representative of our Lohm Resistor. To do this we right-click on our compound component again and this time stay in the “Display Setup” tab. We can click the “Choose Picture” button to upload our own icon. To refresh on the image selector check out the blog post on adding a background image.

To correct the aspect ratio so that it shows up looking less squished on our canvas we want to change the settings back in the Compound Setup tab. I’ll change it to 133×34 so that it appears similar in scale to the standard flow components but correct in the aspect ratio.

Now when we place our compound component onto our canvas it should look great!

Bonus Tips!

  • In the compound component setup there is a third ribbon called “Tooltips Setup”. This is where we can define what properties show up when we hover our mouse over the component.
  • Don’t forget we can save compound components in a “database” on a server so that they can be accessed by every Flownex user in your organization.

Friday Flownex Tech Tips #3

Input Sheet Hacks!

Building on last week’s global parameters example I’d like to show some tricks within the input sheet environment. These are really more so excel tricks – but the methodology within Flownex is slightly different. In this example I am working in Flownex Version 8.12.7.4334

Refresher on using Input Sheets

To create a new Input Sheet we will navigate to the project tab, then select “Excel Reports/Pages”, right-click on the Input Sheets folder, and select “New Input Sheet”

To add inputs to the sheet it’s as simple as dragging and dropping the inputs from the component into the desired cell in the Input Sheet.

Formatting our Input Sheet

I like to use color, shading, and border to specify which cells contain inputs so that if I pass the project off to a client or colleague it is immediately clear what variables they should be editing and which cells they shouldn’t change.

To modify the formatting we need to enter “workbook designer”. This is done by right-clicking on the input sheet and selecting “workbook designer”

All of the standard Excel-type formatting is available here, including adding graphs, images, etc. Typical operations are found in the format menu on the top ribbon.

Drop Downs

A more advanced Excel operation I like to integrate into these types of input sheets is a drop-down where multiple inputs may be tied to a given condition. In the example below I set up a scenario for given ambient temperature for cold day, hot day, and nominal day.

In the workbook designer we will click “insert” > “worksheet” and build our list of environmental conditions. On the right we will set the associated temperatures.

Back on Sheet1 we will need to set up the data validation cell reference to this table. Select the cell where we want to add the dropdown and go to data > validation. We will choose list, and reference cells B2:B4 of Sheet2.

We will need to use VLOOKUP to associate the temp to another cell based on this dropdown. Where this becomes valuable is when we have many input variables tied to each of the dropdown selections.

In this example, since we’ve put the applicable temps a single column to the right the syntax for VLOOKUP will be “=VLOOKUP(B5,Sheet2!B2:C4,2,FALSE)”. After this is added it should behave as follows:

As I mentioned before, this trick becomes very powerful when you have many different environmental or operational inputs tied to a single “scenario” that you want to model in an individual run rather than in a parameter study.

Bonus Tip!

  • All of these tricks can be applied to any of the excel-type sheets within Flownex. Remember to be careful with parameter tables as the inputs and results are tied to the columns instead of individual cells.

Flownex Tech Tips #2

Working with Global Parameters!

As we build more and more networks it quickly becomes tedious to enter in the same inputs many times. There are a couple methods of using global parameters to save us lots of time and clicks. In this example I am working in Flownex Version 8.12.7.4334

Refresher on Global Parameters

Global parameters are just what they sound like. Parameters defined globally for the project. These could be any type of component input; diameter, length, temp, pressure, etc.

The global parameters can be found in a couple of locations. Under the configuration ribbon we can open the global parameters in a floating window which gives us a friendly interface for creating or modifying these parameters. To create a global parameter one may simply right-click in the GlobalParameters window and select Add (hint: there’s a better way!).

Conventional method to add Global Parameter

Global parameters can also be accessed in via the solver tab in a similar way to typical inputs (this is important later on).

The Quick way to add Global Parameters

We don’t really want to have to navigate to that configuration ribbon, right-click a bunch, choose names and assign units do we? Good news! There is a much faster way to add a global parameter. We can add a global parameter with minimal work by simply typing a dollar sign “$” prefacing the name of the tag in any of our component input fields! Remember to hit enter after typing the identifier.

Global Parameter Shortcut

Once a global parameter has been defined we can tie more inputs to the existing parameter by typing the dollar sign “$” and choosing the correct parameter from a drop down:

Multi-Assign Global Parameters

As you can see, this can be quite a time saver when building a network! The next trick utilizing global parameters will have to do with using them for actual analysis.

Using Global Parameters as Manipulatable Inputs

The default/slow way to change a global parameter would be to go to the configuration ribbon > global parameters, and manually change the value in the floating window. No thanks. This is not automated at all and requires many clicks.

The better way to utilize the global parameter as an input would be to tie the global parameter to an input sheet, parameter table (for a parametric study), or even a human machine interface component (HMI).

Global Parameters in Input Sheet

For a design variable that an analyst or engineer may change which would then remain constant (such as pipe diameter) the input sheet comes in very handy. To reference a global parameter in the input sheet recall the second method to access the global parameters and then simply drag and drop onto the input sheet:

Global Parameter in Input Sheet

Global Parameters in Parameter Table

If you are trying to run a parametric study where you are varying something like ambient temperature, it makes sense to use a global parameter as you may have many boundary conditions defined by a single global parameter. Similar to the input sheet this can be tied to a global parameter by a simple drag and drop operation:

Global Parameter as variable in Parameter Table

Global Parameter in a Human Machine Interface

By now I expect you are catching on. The trick to defining a global parameter externally is to use the second method; solver tab > global parameters, and then drag and drop to your desired connection. In the HMI instance I’ve tied inlet mass flow to a Track Bar so that a user can dynamically change the flow rate during the solve:

Global Parameter tied to HMI
Global Parameters and HMI components

Global Parameters are efficient and POWERFUL

We can use global parameters during network construction using the “$” shortcut to build our networks much more quickly and keep identical inputs the same. We can tie these global parameters to other tools to keep our user inputs all in one place, reducing clicks, and reducing the chance of forgetting to update an input.

Bonus Tips!

  • Global Parameters can also be used in Designer so that you can keep your independent to dependent variable count the same (EX: Adjusting ALL pipe diameters to target a single exit flowrate)
  • Global Parameters can be adjusted via transient actions (EX: Adjusting ambient temperature to model the changing temperature over the course of 24 hours).

Adding a Background Image in Flownex

In this post I will go over what is usually the first step in any Flownex network I build. Adding a background image not only helps me lay out my network but also helps colleagues and clients understand networks at a very quick glance. In this example I am using Flownex version 8.12.7.4334

Choosing an Appropriate Image

The first thing we want to do is to make sure that the image size is such that it’s reasonable in size both resolution-wise (so it doesn’t appear pixelated), and right-size so that components don’t appear too small when placed on top. I recommend something in the multi-thousand of pixels both in width an height. 3000 pixels at a minimum. I usually shoot for around 10,000 wide by 5,000 high if the background image will be landscape. For very complex, large networks, it may make sense to go much larger.

Once we’ve found an appropriate image we will want to make a note of the exact size. This can be found by right-clicking on the image file, selecting properties, and navigating to the details tab.

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Confirming Image Resolution

Resizing Flownex Canvas

The canvas in Flownex can be resized to match this resolution by right-clicking on the canvas, selecting edit page, and populating the correct inputs:

Editing Canvas Inputs

Applying Background Image

The background image can be applied by clicking the radio button next to Style in the Appearance subcategory. Here we will change the Fill Style type to Image, then click the Select Image button:

Styles Editor

The images saved locally to this project will appear here. To add an image we simply click Add Image, navigate to the image of our choice, and click open. Now that it is available as an option we select the image in the Image Selector Gallery and click OK.

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Image Selector Gallery

We can press OK in the Styles Editor to confirm our changes and we should now see our added image as the new background!

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Drawing Canvas with Background Image

Bonus Tips!

  • Adjusting the Fill Style opacity can fade out the background image so that it doesn’t overwhelm the Flownex components placed on top.
  • Turning off the grid under the View ribbon can make the canvas a bit more aesthetically pleasing.

Press Release: Ansys Elite Channel Partner and Stratasys Diamond Channel Partner, PADT Announces Jim Sanford as Vice President of Sales & Support

The Sales and Support team at PADT is the group that most of PADT’s customers interface with. They sell world-leading products from Ansys, Stratasys, and Flownex and then provide award-winning support long after the initial purpose. The team has grown over the years and has plans for even more growth. To help make that happen, we are honored to have Jim Sanford join the PADT family as the Vice President of our Sales & Support team.

Many of our customers and partners know Jim from his time with industry leaders Siemens, MSC, Dassault Systems, and NextLabs, Inc. He brings that experience and his background as a mechanical engineer before he entered sales, to focus PADT on our next phase of growth. He also fit well in PADT’s culture of customer focused, technical driven sales and support.

Our customers have a choice of who they purchase their Ansys multiphysics simulation, Stratasys 3D Printers, and Flownex system simulation software from, and who delivers their frontline support. We know with Jim leading the team, even more companies will make the choice to be part of the PADT family.

The official press release has more details, and can be found at these links or in the test below.

Press Release: PDF | HTML

Want to have a conversation about your Simulation or 3D Printing situation? Contact PADT now and one of our profesionals will be happy to help.


Ansys Elite Channel Partner and Stratasys Diamond Channel Partner, PADT Announces Jim Sanford as Vice President of Sales & Support

Sanford Brings a Wide Range of High-Profile Leadership Experience Across Technology and Aerospace and Defense Sectors to his New Position

TEMPE, Ariz., February 11, 2021 PADT, a globally recognized provider of numerical simulation, product development, and 3D printing products and services, today announced the addition of Jim Sanford as vice president of the company’s Sales & Support department. In his new position, Sanford is responsible for leading the increase of sales and customer support for a range of best-in-class simulation and additive manufacturing solutions. Sanford reports to Ward Rand, co-founder and principal, PADT.

“In the last few years, PADT has expanded across the Southwest, adding new expertise and technologies to our product and service offerings,” said Rand. “Jim is a valuable addition to the team and will be instrumental in sustaining PADT’s growth across the region. His leadership, experience, and knowledge of the industry will allow us to increase the pace of expansion and bring our solutions to serve new and existing customers in deeper and more impactful ways to their businesses.”

After a comprehensive search, Sanford proved to be the most experienced and capable leader to take on the vice president role. He will focus on providing visionary guidance, strategy, and tactical direction to the department. His responsibilities include refining the company’s sales team structure, recruiting, hiring, training, managing for profitable growth, and leading the support team to ensure an optimal customer experience for their use of Ansys, Stratasys, and Flownex products.

Prior to joining PADT, Sanford held business development and engineering positions in a diverse range of aerospace and defense, modeling and simulation, and software companies. His 30-year career span includes executive leadership roles at Siemens, MSC, and Dassault. Most recently he served as the VP for NextLabs Inc., a leading provider of policy-driven information risk management software for large enterprises, and the VP of Business Development for Long Range Services, where he was engaged in the development and testing of various classified items for the U.S. Department of Defense. He holds a bachelor’s degree in Mechanical Engineering from the University of Arizona, with emphasis in materials science and physics.

“PADT is a well-respected brand well-known for its product knowledge, customer-centric approach, and expertise,” said Sanford. “My career has been defined by my ability to take technology-focused companies to the next level of success, and I’m thrilled to join PADT and help continue its expansion by supporting highly innovative customers.”

PADT currently sells and supports the entire Ansys product line in Arizona, California, Colorado, Nevada, New Mexico, Texas, and Utah as an Ansys Elite Channel Partner. They also represent all Stratasys products in Arizona, Colorado, New Mexico, Texas, and Utah as a Diamond Channel Partner and are the North American distributor for Flownex.

To learn more about Sanford and PADT’s products and services, please visit https://www.padtinc.com/products/

About PADT

PADT is an engineering product and services company that focuses on helping customers who develop physical products by providing Numerical Simulation, Product Development, and 3D Printing solutions. PADT’s worldwide reputation for technical excellence and experienced staff is based on its proven record of building long-term win-win partnerships with vendors and customers. Since its establishment in 1994, companies have relied on PADT because “We Make Innovation Work.” With over 90 employees, PADT services customers from its headquarters at the Arizona State University Research Park in Tempe, Arizona, and from offices in Torrance, California, Littleton, Colorado, Albuquerque, New Mexico, Austin, Texas, and Murray, Utah, as well as through staff members located around the country. More information on PADT can be found at www.PADTINC.com.

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Building a System Model of the RL-10 Rocket Engine in Flownex

When we engineers are building a new system or iterating on an existing design it can be expensive.  Simulating a full system-level model in a 3D CFD program can take days.  Making iterative changes to an existing system can be costly or even impossible. Utilizing a one-dimensional system modeler like Flownex allows us to analyze many different designs very quickly, on the order of seconds or minutes.

Flownex is a thermal-fluid network modeler.  It is a simulation tool that allows for 1D fluid modeling and 2D heat transfer.  It uses a variety of flow components, nodes, and heat transfer elements to model the entire system we are interested in analyzing.  It solves conservation of mass, momentum, and energy to obtain the mass flow, pressure, and temperature of fluids and solids throughout the complete network.  Because of this approach we can analyze large, complex networks very quickly, iterate on designs, and even run short or long transient simulations with ease.

In the example today we are looking at a version of the RL-10 rocket engine, which has been a staple in the delivery of satellites into orbit and an essential part of many spacecraft. The specific iteration of the RL-10 we will be using for building our network model is the RL10A-3-3A. A good place to begin with any system model is a system schematic:

Figure 2: RL10A-3-3A Engine System Schematic – Image from https://ntrs.nasa.gov/citations/19970010379

In Flownex we can assign an image (could be from a P&ID diagram, a CAD cross-section, or even a satellite image!) as the background for our drawing canvas. We simply need to right-click on the drawing canvas and select Edit Page to bring up the drawing canvas properties.

Clicking on the action button under Appearance Style brings up the Styles Editor.  Here we can change the fill style to Image and select the appropriate image for our background.

In the case of the RL-10 we can use the image from figure 2 as our background image.  We may want to consider adjusting the opacity of the image so that it blends into the background a little bit more.

In Flownex building a system model is as simple as drag and drop.  We can build our rocket engine using a variety of flow components from the Flow Solver library. To build the RL-10 system model we will be using the following components:

CEA Adiabatic Flame component to model combustion.

Composite Heat Transfer component to model thermal transport through pipe-walls to ambient and to model the regen.

Boundary Conditions to constrain our system at the inlets and outlet.

Basic Valves to model the different valves in the system,

Flow Resistances to model specified losses where appropriate.

Flow Interfaces to model the fluids entering the combustion chamber (to transfer fluid properties as we switch from two-phase O2 and H2 to gaseous fluids for modeling combustion.

Pipes for modeling various flow-paths.

Restrictors with Discharge Coefficient for our injection ports to the combustion chamber.

Restrictors with Loss Coefficient to model both the Calibrated Orifice and the Venturi contraction/expansion.

Basic Centrifugal Pumps for our Fuel and LOX pumps.

Simple Turbine to model the Fuel Turbine

Shafts to connect our different pumps mechanically.

Gearbox is used to connect the shafts between the LOX pump and the Fuel Pump.

Exit Thrust Nozzle to determine total thrust.

Script is used in assigning O2 properties prior to combustion.

The components may be dragged and dropped from the component library onto the drawing canvas to build our system model. We can also copy and paste components that are already on the canvas into different locations. This can be especially useful when the same inputs for say, a pipe, are used consistently throughout the model. All components have both Inputs and a Results associated with them as seen in the figure below. This is how we will define our flow components.

The completed model of the RL-10 Rocket Engine can be seen below. There are a few simplifications; we are using composite heat transfer components to model free convection to a specified ambient temperature (as though this was a land-based test). Rather than tie the actual temperatures and flow conditions in the nozzle to the regen we are using assumed temperatures and convective heat transfer coefficients. For additional fidelity we could model the heat transfer between these two flow paths with calculated convective heat transfer coefficients and we could model cross-conduction along the pipes which deliver the fuel and oxidizer to the combustion chamber. With additional effort, more complex use cases could also be simulated.

For the sake of demonstration we set up a transient action to slowly vary the oxidizer control valve fraction open; starting at 30% and ending at 100% open and observer the change in thrust at the nozzle as a function of this changing transient action.

Plots may be easily added by dragging a Line Graph from the Visualization > Graphs section of the component library onto our canvas. To choose the characteristics we would like plotted against time we simply need to drag and drop the desired inputs or results onto our newly placed line graph.

RL-10 Transient Thrust Plot

We can plot both the oxidizer control valve fraction open and the thrust versus time to observe the thrust reaction to the opening of the valve. The thrust plot has some jumps that are likely due to numerical singularities – with additional work this could be improved.

As can be seen, setting up complex system models in Flownex is relatively simple with most operations being drag and drop. For ease of sharing models with colleagues or customers adding a background image makes it very easy to see how the flow components in the model correspond with a system schematic. Setting up and plotting the effects of operational transients is a breeze!

For more information on Flownex please reach out to Dan Christensen at dan.christensen@padtinc.com.

All Things ANSYS 020 – Modeling Flow & Heat Transfer with Flownex

 

Published on: September 10th, 2018
With: Eric Miller, Luke Davidson, Vincent Britz, and Farai Hetze
Description: In this episode your host and Co-Founder of PADT, Eric Miller is joined by Luke Davidson and Vincent Britz of M-Tech, and Farai Hetze from CFX-Berlin, for an interview on the what Flownex is, it’s capabilities for modeling flow and heat transfer, and how it works with ANSYS products. All that, followed by an update on news and events in the respective worlds of ANSYS and PADT.

If you have any questions, comments, or would like to suggest a topic for the next episode, shoot us an email at podcast@padtinc.com we would love to hear from you!

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Getting to Know PADT: Flownex Sales and Support

This is the second installment in our review of all the different products and services PADT offers our customers. As we add more, they will be available here.  As always, if you have any questions don’t hesitate to reach out to info@padtinc.com or give us a call at 1-800-293-PADT.

The PADT sales and support team focused on simulation solutions is best known for our work with the full ANSYS product suite.  What a lot of people don’t know is that we also represent a fantastic simulation tool called Flownex. Flownex is a system level 1-D program that is designed from the ground up to model thermal-fluid systems.

What does Flownex Do?

Flownex Simulation Environment is an interactive software program that allows users to model systems to understand how fluids (gas and/or liquid) flow and how heat is transferred in that same system due to that flow.  the way it works is you create a network of components that are connected together as a system.  The heat and fluid transfer within and between each node is calculated over time, giving a very accurate, and fast,  representation of the system’s behavior.

As a system simulation tool, it is fast, it is easy to build and change, and it runs in real time or even faster.  This allows users to drive the design of their entire system through simulation.

Need to know what size pump you need, use Flownex.  Want to know if you heat exchanger is exchanging enough heat for every situation, use Flownex.  Tasked with making sure your nuclear reactor will stay cool in all operating conditions, use Flownex.   Making sure you have optimized the performance of your combustion nozzles, use Flownex.  Time to design your turbine engine cooling network, use Flownex. Required to verify that your mine ventilation and fire suppression system will work, use Flownex. The applications go on and on.

Why is Flownex so Much Better than other System Thermal-Fluid Modeling Solutions?

There are a lot of solutions for modeling thermal-fluid systems. We have found that the vast majority of companies use simple spreadsheets or home-grown tools. There are also a lot of commercial solutions out there. Flownex stands out for five key reasons:

  1. Breadth and depth of capability
    Flownex boasts components, the objects you link together in your network, that spread across physics and applications.  Whereas most tools will focus on one industry, Flownex is a general purpose tool that supports far more situations.  For depth they have taken the time over the years to not just have simple models.  Each component has sophisticated equations that govern its behavior and user defined parameters that allow for very accurate modeling.
  2. Developed by hard core users
    Flownex started life as an internal code to support consulting engineers. Experienced engineering software programmers worked with those consultants day-in and day-out to develop the tools that were needed to solve real world problems.  This is the reason why when users ask “What I really need to do to solve my problem is such-and-such, can Flownex do that?” we can usually answer “Yes, and here are the options to make it even more accurate.”
  3. Customization and Integration
    As powerful and in-depth as Flownex is, there is no way to capture every situation for every user.  Nor does the program do everything. That is why it is so open and so easy to customize and integrate. As an example, may customers have very specific thermal-pressure-velocity models that they use for their specific components. Models that they developed after years if not decades of testing. Not a problem, that behavior can be easily added to Flownex.  If a customer even has their own software or a 3rd party tool they need to use, it is pretty easy to integrate it right into your Flownex system model.Very common tools are already integrated. The most common connection is Matlab/Simulink.  At PADT we often connect Excel models from customers into our Systems  for consulting.  It is also integrated into ANSYS Mechanical.
  4. Nuclear Quality Standards
    Flownex came in to its own as a tool used to model the fluid system in and around Nuclear Reactors.  So it had to meet very rigorous quality standards, if not the most stringent they are pretty close. This forced to tool to be very robust, accurate, and well documented. And the rest of us can take advantage of that intense quality requirement to meet and exceed the needs of pretty much every industry.  We can tell you after using it for our own consulting projects and after talking to other users, this code is solid.
  5. Ease of Use
    Some people will read the advantages above and think that this is fantastic, but that much capability and flexibility must make it difficult to use. Nothing could be further from the truth.  Maybe its because the most demanding users are down the hallway and can come and harangue the developers. Or it could be that their initial development goal of keeping ease of use without giving up on functionality was actually followed.  Regardless of why, this simulation tool is amazingly simple and intuitive.  From building the model to reviewing results to customization, everything is easy to learn, remember, and user.  To be honest, it is actually fun to use. Not something a lot of simulation engineers say.

Why does buying and getting support from PADT for Flownex make a Difference?

The answer to this question is fairly simple: PADT’ simulation team is made up of very experienced users who have to apply this technology to our own internal projects as well as to consulting jobs.  We know this tool and we also work closely with the developers at Flownex.  As with our ANSYS products, we don’t just work on knowing how to use the tool, we put time in to understand the theory behind everything as well as the practical real world industry application.

When you call for support, odds are the engineer who answers is actually suing Flownex on a customer’s system.  We also have the infrastructure and size in place to make sure we have the resources to provide that support.  Investing in a new simulation tool can generate needs for training, customization, and integration; not to mention traditional technical support. PADT partners with our customers to make sure they get the greatest value form their simulation software investment.

              

Reach out to Give it a Try or Learn More

Our team is ready and waiting to answer your questihttp://www.flownex.com/flownex-demoons or provide you with a demonstration of this fantastic tool. .  You can email us at info@padtinc.com or give us a call at 480.813.4884 or 1-800-293-PADT.

Still want to learn more? Here are some links to more information: