GT-POST Tutorials GT-SUITE

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GT-SUITE

GT-POST Tutorials

VERSION 7.4

by

Gamma Technologies

All information contained in this manual is confidential and cannot be reproduced or transmitted in any form or by any means, electronic or mechanical, for any purpose, without

the express written permission of Gamma Technologies, Inc.

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GTI SUPPORT

• TELEPHONE: (630) 325-5848

• FAX: (630) 325-5849

• E-MAIL: support@gtisoft.com

• Web Address: www.gtisoft.com

• Address: 601 Oakmont Lane, Suite 220 Westmont, IL 60559

USA

Telephone Support Hours

8:00 A.M. to 5:30 P.M. Central Time Monday – Friday

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TUTORIAL 1: General Use of GT-POST

This tutorial has been prepared to teach a new user about GT-POST. GT-POST is a plotting and data- handling tool used by GT-SUITE. Several uses of GT-POST are shown in this tutorial through consecutive sections analyzing the results of a basic engine simulation. Although this tutorial focuses on post-processing results of engine simulation models, the use of GT-POST is identical with all applications and thus this tutorial will be beneficial for all users of GT-SUITE software.

1.1 Introduction

Several methods for analyzing simulation results are offered in GT-POST. Below is a list of the different post-processing formats in GT-POST.

Instantaneous Plots: These plots are of values with respect to the crank angle for GT-POWER over the last cycle of each case. These are very useful for looking at how things change over one cycle of the engine. For example, it is helpful to look at how the mass flow rate or lift of the valves varies with the crank angle.

Case RLT Plots: These plots are made from all the RLT (results) data gathered for the various part variables from the model simulation. They are very useful for analyzing results of simulations with several cases where a specific variable changes for each case. The RLT results stored are steady-state periodic simulations where the results are averaged over the last cycle of each case. For example, comparing a varying engine speed over several cases with the volumetric efficiency, power, torque, or many other variables will produce important performance plots.

Time RLT Plots: These plots are for transient simulations since they are cycle-averaged quantities that vary with time during a transient event. If, for example, the engine is varying speeds with respect to time throughout the simulation, then these plots will show the effect of this variation on the engine measurements.

RLT Contour Map: This is a visual representation of the Case RLT data, using color contours to represent values. The contoured data is then overlaid on the model display to show parameter variations everywhere in the model. A global view of the model is given for each case. This can be useful for trying to understand how conditions vary in different areas of the engine.

Animated Contour Map: This is a feature that allows the user to view what is happening throughout the cycle of the entire engine model. It is much like the RLT Contour Map since it shows the entire engine and uses color-contours to display the values. However it shows the Time RLTs for a complete cycle.

This gives very specific visual results; for example displaying the pressure at many instants in time throughout the cycle can help one determine when certain parts are reaching their maximum pressure.

Tables: Tables can be created to view Case RLT data collected and save it for future reference. Many tables of data are created by GT-POST automatically in the GX file; however, many other tables can be created with only requested data.

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1.2 Set-up

Before the post-processing, a model must be run to obtain simulation results. From GT-ISE, open the

model file SI_4cyl_Basic.gtm located in

%GTIHOME%\vX.X.0\examples\Engine_1D_Gas_Exchange_Combustion\Gasoline\SI_4cyl_Basic folder and run the example model. This four-cylinder engine will be used to generate the results used for post-processing.

Once the simulation is finished, two of the several output files created are called SI_4cyl_Basic.gx and SI_4cyl_Basic.gdt. These are the primary files used by GT-POST, and they contain all of the data from the simulation. Open GT-POST by clicking the GT-POST icon from the GT-ISE toolbar, or by selecting Run/Open GT Post. Select the SI_4cyl_Basic.gx file if it is not automatically selected, and click Open. This will open a GT-POST window, which will look similar to Figure 1 shown below.

Note: Some figures may appear slightly different from your screen due to desktop settings or other changes to the GT-POST interface.

Figure 1: The GT-POST window

1.3 Viewing a Plot

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2. Scroll down to the EngineCrankTrain group, and expand to the Flow data for the engine by first clicking on the plus symbol to the left of the EngineCrankTrain group. Next, expand the engine data by clicking on the plus symbol to the left of the Engine part. Then, expand the Flow folder.

The window should then look similar to Figure 2 below.

Figure 2: The Case RLT tree format.

3. Right-click on the first data set called Volumetric Efficiency, Air and select View. Pressing F4 on the keyboard will also display the highlighted data set. The plot should appear in the default settings similar to Figure 3. The plot window can be moved and re-sized if necessary.

Note that on this plot, the X-axis has been set up to display Engine Speed (RPM) instead of case number, which is the default. This can be done before the simulation is run in GT-ISE by opening the Run menu and selecting Output Setup. Then, in the GT-POST_Setup tab, use the Value Selector to change X- Axis RLT for Case Sweep Plots to the Engine Speed RLT, or any other RLT variable that is desired.

CaseRLT Tab

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Figure 3: A plot of the volumetric efficiency for each engine speed.

1.4 Customizing a Plot

Before beginning to customize the plot, a new file that must be created so the plot properties can be saved. This file is called a User Plots File or GU file. The GU file does not store the simulation data explicitly; it is linked to the results data *.gdt file implicitly. The plots created in the GU file will be updated if the simulation data changes.

1. Select the New GU toolbar button and an empty GU window will appear as shown in Figure 4.

2. Change the name to correspond with the GX file by choosing Save As in the File menu, and then name the file "SI_4cyl.gu".

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Figure 4: The new GU icon and window.

Plot properties can be changed in the GX file, but these changes cannot be saved. Therefore, plots and plotting formats are usually customized in a GU file.

A standard initial group named New Group is in the GU file so that a plot can be immediately copied into the file.

1. Change the name of this New Group to RLT Plots by double-clicking on the name to open the properties window and changing the Name, or by right-clicking and selecting Rename.

2. Highlight and drag the Volumetric Efficiency, Air CaseRLT plot from the GX file into the RLT Plots group in the SI_4cyl.gu file.

It is important to note that the GU file has four levels in the tree format: title, group, plot, and data level.

These levels are labeled in Figure 5, and they can be expanded the same way as in the GX file. They are important since some properties can only be changed from certain levels. It is also important to know that a change made at a higher level will affect the sub-levels below. Changes can be made to a given level by right-clicking on the level in the tree and selecting Properties, or by right-clicking on the plot and then selecting the properties option for the appropriate level.

New GU window

New GU button

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Figure 5: Labeled levels in the SI_4cyl.gu file.

First, make the changes to the axis and format of the plot in the following manner.

1. Right-click on the plot or the Plot level in the tree and select Plot Properties. From this window, the X-axis, Y-Axis, and general plot format can be changed.

2. To add minor divisions on the X-axis, select Scale from the X-axis tree. The Minor Divisions box specifies the number of minor divisions per major division. In the Minor Divisions box, put a 2 to place a tick-mark on the X-axis at 500 RPM intervals.

3. To change the Grid Lines for the Y-axis, click on Grid in the Y-axis tree, and select short-dash as the Grid Lines type. Also to use easy to read numbers for the axis, set the minimum and maximum for the range to be Auto under the Scale.

4. The axis labels can be changed from Labels.

5. Press the OK button to save the changes to the Plot Properties.

Now, change the way the data points are shown.

1. Right-click on the SI_4cyl data level and choose Properties. The properties window can also be reached by right-clicking on the plot and selecting Data Properties and SI_4cyl.

2. In the Display branch of the tree, change the Symbols: Style to increment to add the data markers. The markers will be selected according to the rules specified in Tools > Options >

Plot Auto Increment Settings. Increment rules for the line type and color can also be changed.

3. The line thickness, type, color, and data symbols can also be changed. Mathematical operations can also be performed from the Data Properties window.

4. Press the OK button to save the changes to the Data Properties.

Re-generate the plot by selecting the plot and pressing F4 to view. The plot should look similar to Figure 6 after all of the changes have been made.

Title Level

Group Level

Plot Level

Data Level

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Figure 6: The formatted plot of volumetric efficiency for each engine speed.

In GT-POST, the current plot view is called the Live View, and is represented by the symbol in the tab at the bottom of the plot window. Display properties of a Live View plot can be altered both from right- clicking in the plot window and by right-clicking on the plot or data name in the GU window. When a new View command is issued for a different plot, the default GT-POST behavior is to take a Snapshot of the current plot and create a new Live View plot with the data requested by the user. A Snapshot, represented by the symbol , is a plot not linked to a GX or GU file and is stored in short term memory.

The Snapshot can only be altered from property changes made in the plot window. A Live View plot is directly linked to the GX or GU file, so if a simulation is re-run and results change the Live View plot will be updated accordingly. One further note is that changes made to the plot in a Live View window are saved when the Live View is switched, whereas changes made to a Snapshot are lost if the Snapshot is closed. Snapshots can also be pinned to the plot window using the Pin Snapshot button to prevent them from being easily closed.

To change the default behavior for Snapshot creation, select Tools/Options… and go to the Plot/Table Viewing tab. Uncheck the box next to “Automatically create snapshot when plotting” if Snapshot creation is not desired. To manually create a snapshot when this option is turned off, right-click on the tab at the bottom of the plot window and select Make Snapshot.

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1.5 Creating Multiple Plots

To create multiple plots of result variables at once, use the RLT Plots macro button . This macro can also be accessed by selecting Macro/RLT Plots…. In this section, plots of the Brake Power (HP), Brake Mean Effective Pressure (BMEP), and Brake Specific Fuel Consumption (BSFC) vs. the Engine Speed will be created.

1. Click on the SI_4cyl_Basic.gx window to make sure that it is activated, because the macros can only be used if the GX file is activated. Click on the RLT Plots macro button on the toolbar or in the Macro menu.

2. Choose the Case RLT RLT Type, and the XY Scatter Plot Plot Type, and click Next.

3. Find and select the Engine Speed RLT (cycle average) in the Performance Folder of the EngineCrankTrain component.

4. Click on the variable while the cursor is in the X column. This will be the X variable for all further plots selected.

5. Move the cursor to the Y1 column / Plot1 row in the top window, and then select the following variables: Brake Power (HP) (in the Torque-Power Folder), BMEP (in the Performance Folder), and BSFC (in the Performance Folder).

6. Once the Data tab has the same RLTs as Figure 7, select Next. In the Dataset Label and Display Options, select “Model Name” and unselect Part Name, RLT Name, and Constraint RLT. Make sure that the Document Name is SI_4cyl.gu, and click Finish to create the plots.

These three plots should now be listed in the SI_4cyl.gu file.

Figure 7: The Plot RLT Macro window.

1.6 Customizing Multiple Plots

The tree system enables multiple plots to be customized simultaneously. To change the properties for several plots in a group, change the Children Properties for that particular group. In this section, the newly created plots will be formatted like the Volumetric Efficiency plot.

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3. To only change the values for certain plots, uncheck the box next to that tree item in the Select Tree Elements window (Figure 8). Since all of the plots will be formatted the same, leave all of the boxes checked and click Next.

Figure 8: Select Tree Element Window

4. Go to the Scale branch of the X-Axis tree, and then the Minor Divisions box. Change the number in the box to 2; this divides the Major Intervals into 500 RPM intervals.

5. To change the Grid Lines on the Y-axis, click on the Grid branch of the Y-axis tree, and select short-dash as the Grid Line type. Also, to use easy to read numbers for the axis, go to the Scale branch select the minimum and maximum for the range to be Auto. Click Finish to display the updated plots.

6. To change the symbol type, re-open the Children Properties window by right-clicking on the RLT Plots group level in the SI_4cyl.gu window.

7. In the Property Type window, change the Property type to Data, and click Next to advance to the Select Tree Elements window. Ensure that the boxes next to each plot are checked, and click Next. In the Property Modification window, choose the Display tree branch and change the Symbols: Style to increment.

8. Click Finish to display the formatted plots.

All 4 of the graphs in the RLT Plots SI_4cyl.gu file will now have the same properties. Flip through the 4 plots by using the page left/page right buttons on the toolbar. To view all 4 plots on the same screen, select the RLT Plots group, and then right-click and select Properties. Then select 2x2 from the dropdown next to the Layout: option. Click OK and the plot screen should look similar to Figure 9. To change back to 1 plot per page, change the Layout dropdown back to 1x1.

Select Box

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Figure 9: The CaseRLT plots displayed in a 2x2 array.

1.7 Entering Data Manually

Tabulated data can be added to a GT-POST plot. Data entered manually is explicitly stored in the GU file. Sample data is provided for the Volumetric Efficiency, and is shown in Table 1 below.

Table 1: Sample Volumetric Efficiency Data Engine Speed (RPM) Volumetric Efficiency

6000 0.9621

5500 1.0228

5000 1.0119

4500 1.0021

4000 0.9718

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1. Enter this sample data manually by right clicking on the Volumetric Efficiency Plot level, and then selecting Add Data.

2. Select Explicit for the Data Source and click Next.

3. Enter the Data Name: "Sample", and then click Finish. For other data sets, the units can be changed to convert the entered data to match the simulation units.

4. Enter the data from Table 1, and select OK. The column titles do not need to be entered in to GT-POST.

5. Select the Volumetric Efficiency plot from the tree and press F4 (if Automatic view is not selected) to view the plot.

The sample data will be plotted on the same graph as the simulation output data for Volumetric Efficiency. By default, the "Sample" set will be the first data set in the plot. The line color is automatically specified by the data set order; therefore it should be easy to differentiate between the data sets. The data set order can be changed by dragging the icon for the set to the desired position in the GU window tree diagram. Properties of each data set can be also be specified individually.

1. Right-click on the Sample data level under the Volumetric Efficiency plot level in the GU window, and select Properties.

2. In the Display branch of the tree, change the Symbols: Style to increment and press the OK button to add the data markers.

The formatted plot should look similar to Figure 10.

Figure 10: The plot of the sample and simulation data for Volumetric Efficiency.

1.8 Importing Data from Text Files

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Data contained in text files can also be imported into GT-POST. Sample data for the Brake Power (HP) has been provided in the Experiment.txt file located in the %GTIHOME%\v7.x.0\tutorials

\Graphical_Applications\GTpost\01-GeneralUse\ folder. Open the file Experiment.txt in a text editor to ensure that it matches Figure 11.

Figure 11: Text File with Experimental Data

Import the experimental data for the Brake Power (HP) contained in this text file by doing the following:

1. Right-click on the Brake Power (HP) plot level and select Add Data.

2. Select Ascii for the Data Source, find the file named Experiment.txt by using the Browse button, and click Next.

3. Configure the Delimiters to only be Tab, and select Next.

4. Because the text file has a title row, only the column titles and data need to be imported.

Highlight the row containing the Engine Speed and Brake Power labels and move the data to the right window by pressing the button. Make sure the "Take Whole Column" checkbox is selected to move all of the data.

5. In the right window, change the first row from Data to Label. The first two rows of the imported information can be specified as Data, Label, or Unit to match the format of the file. The rest of the rows are assumed to be Data.

6. Select Next to review the Data Options. ASCII data may be imported implicitly, meaning that if the .txt file is updated with new data the GT-POST plot will be updated accordingly, or explicitly, which makes a copy of the data in the .txt file at the time and stores the data in the GU file.

7. Select Finish to create the data set.

8. Drag the Brake Power (HP) data set to the second position in the Brake Power (HP) plot level in the GU window.

9. Select Properties after right clicking on the Brake Power (HP) data level.

10. In the Display branch of the tree, change the Symbols: Style to increment to add the data markers. The plot should look similar to Figure 12.

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Figure 12: Plot of Experimental & Simulation Data for Brake Power (HP)

1.9 Importing Data from Excel

Data contained in excel files can also be imported into GT-POST. Sample data for the Brake Mean Effective Pressure (BMEP) has been provided in the ExperimentData.xls file located in the

%GTIHOME%\v7.x.0\tutorials\Graphical_Applications\GTpost\01-GeneralUse\ folder. The steps for importing an Excel file follow similar steps to importing an Ascii file.

1. Right-click on the Brake Mean Effective Pressure plot level and select Add Data.

2. Select Excel for the Data Source, find the file named ExperimentData.xls by using the Browse button, and then click Next.

3. To import the entire data set, select the top row of the spreadsheet. Move the information to the right window by pressing the button. Make sure the "Take Whole Column" checkbox is selected to move all of the data.

4. In the right window, select the "Label" and "Unit" option for rows 1 and 2, respectively.

5. Select Next to review the Data Options. Excel data may be imported implicitly, meaning that if the .xls file is updated with new data the GT-POST plot will be updated accordingly, or explicitly, which makes a copy of the data in the .xls file at the time and stores the data in the GU file.

6. Select Finish to create the plot.

7. Arrange the data and format the dataset like the previous plots. The plot should be similar to Figure 13.

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Figure 13: Plot of Experimental & Simulation Data for BMEP

Since we do not yet have experimental data for the BSFC, we can unselect the check mark for that plot.

Now plot all 3 plots by highlighting the group 'RLT Plots' and pressing F4.

1.10 Comparing Two Different Models

Another model has been created to illustrate the method for comparing similar GT-ISE models. The new model is based on the SI_4cyl_Basic.gtm model used previously; the intake and exhaust geometry has been changed. The intake runner length has been increased from 320 mm to 380 mm, and the exhaust runner length has been increased from 250 mm to 300 mm. This new model is titled SI_4cyl_long.gtm and is located in the %GTIHOME%\v7.x.0\tutorials\Graphical_Applications\GTpost\01-GeneralUse\

folder.

It is important to know that once a GU file is built for a model, the GU file does not have to be built again for a second similar model. If changes are made to the model and the results need to be compared, this can be done by adding the similar model information to the GU file to create new plots. The pointers used to specify the data for the first model are used for the second model.

For convenience, the SI_4cyl_long.gtm model has already been run. The files SI_4cyl_long.gx and SI_4cyl_long.gdt are contained in the same folder as the model, and the data will be added to the current GU file.

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3. Select SI_4cyl.gdt as the File to copy and browse to find SI_4cyl_long.gdt in the above directory as the File to replace with.

4. Click Next.

5. Under the Data Label Settings, select New and enter SI_4cyl_long, and then select Finish.

Now all the plots in the RLT Plots group will have 3 data sets each except for the BSFC plot with 2 data sets. With the use of Change Data Source, all of the pointers referring to SI_4cyl.gdt were copied and changed to point to SI_4cyl_long.gdt. To view only the new data, use the Data Selection Wizard. The Data Selection Wizard can be used to easily change the source data displayed for multiple plots.

1. Select only the data sets belonging to SI_4cyl_long by right clicking on the RLT Plots group and selecting Turn On/Off Datasets to launch the Data Selection Wizard.

2. In the Select Datasets window, uncheck the boxes next to the files SI_4cyl.gdt, Experiment.txt, and ExperimentData.xls.

3. Select Finish to exit the wizard.

4. Because explicit data is not affected by the Data Selection Wizard, uncheck the box next to the Sample dataset for the Volumetric Efficiency plot.

5. View the plots for the new data.

6. Then re-display the data from the first model, by using the Data Selection Wizard again, and select/check the boxes for SI_4cyl.gdt, Experiment.txt, and ExperimentData.xls.

For a direct comparison between the two models, the Plot/Table Math Operations macro can be used to plot the percent difference in Brake Power between the SI_4cyl and the SI_4cyl_long simulations.

1. Activate the SI_4cyl.gu file by clicking on the GU window.

2. Click on the Plot/Table Math Operation macro button in the GT-POST toolbar or select it from the Macro menu.

3. Under the Select operation type menu, Select Percent Difference and press Next.

4. Expand the RLT Plots tree to display the plots. Expand the Brake Power plot, and drag the SI_4cyl_long data set down into the Build math dataset(s) pane. It will be assigned as the Y1 data set.

5. Next, drag the SI_4cyl_Basic set down. It will be assigned as the Y2 data set. Click Next.

6. Change the User Group to <Create New Group> and press Finish.

The plot should be similar to Figure 14.

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Figure 14: Plot of the percent difference in Brake Power between SI_4cyl_long and SI_4cyl.

1.11 Creating Tables

Tables of simulation data can also be created using GT-POST. A table containing the Volumetric Efficiency, Brake Power, Brake Mean Effective Pressure, and Brake Specific Fuel Consumption can be created for data storage in the following manner.

1. Activate the SI_4cyl_Basic.gx file, and click on the RLT Tables icon in the toolbar or from the Macro menu.

2. From the Performance folder in the EngineCrankTrain Component, select the data that is required to be included in the table by clicking on the RLT variable names: Engine Speed, Volumetric Efficiency (in Flow folder), Brake Power (HP) (in Torque/Power folder), Brake Mean Effective Pressure, and Brake Specific Fuel Consumption. The variable table should look like Figure 15.

3. Click OK to create the table.

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Once this table is created, it will be placed under the Tables tab in the SI_4cyl.gu file in the new group.

The name of the table needs to be changed from the default "New Report Table1" to "RLT Data" by right-clicking on the name and choosing Rename. The table should look like Figure 16.

Figure 16: Table of RLT Data

1.12 Viewing Instantaneous Plots

The Instantaneous Plots, which plot variables with respect to Crank Angle or Time for GT-POWER, will be used to analyze the results in the valves. The Part Data Combine macro can be used to compare similar instantaneous data from the same part types. For this example, the mass flow rate from the intake and exhaust valves will be compared for a given crank angle.

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1. Activate the SI_4cyl_Basic.gx window, and then select the Plot Data Combine toolbar button or use the Macro menu.

2. In the left pane, select the mass flow rate data from one of the exhaust valves (ValveCamConn:ExVal1A or B).

3. In the middle pane, select the mass flow from the matching intake valve.

4. In the right pane, select all the cases.

5. Finally change the User Group to <Create New Group>. The dialog should look like Figure 17.

6. Now, press OK.

7. In the .gu window, rename the newly created group as "Instantaneous Plots".

Figure 17: The Plot Data Combine window.

The plots should look similar to Figure 18 for the mass flow rate of the intake and exhaust valves.

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Figure 18: The instantaneous plot of the mass flow rate through the valves compared to the crank angle.

1.13 Combining Cases of Instantaneous Plots

In this example, the mass flow rate vs. crank angle for the intake valve will be compared for several different cases in the same plot. Use the Plot Case Combine macro since this will allow plotting several cases on one graph for better comparisons.

1. Once again, activate the SI_4cyl_Basic.gx file then select the Plot Case Combine macro button in the toolbar, or from the Macro menu.

2. In the left hand pane of the window, select the Mass Flow Rate data level for InVal1A. Note that a red check-mark must appear in the box next to the data set to indicate that it is selected.

3. On the right hand side, select cases 1, 3, 5, and 7 by single-clicking on each case.

4. Also change the User Group to Instantaneous Plots, and the window should look like Figure 19.

5. Select OK to create the plot.

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Figure 19: The Plot Case Combine / Repeat window.

The individual curves are automatically differentiated by color. To further differentiate the curves, the line type can be changed for each data set.

1. Right-click on the Mass Flow Rate plot level, and select Children Properties.

2. Select Data from the Property Type panel, and click Next.

3. Ensure that all of the cases are selected, and click Next.

4. From the Display option on the tree, Change the Line: Style to increment, and click Finish.

5. Each line will have a unique line type, and the plot should look similar to Figure 20.

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Figure 20: The instantaneous case combine plot of the mass flow rate through the intake valve for different engine speeds at varying crank angles.

The labeling on the datasets should also be mentioned. In SI_4cyl_Basic.gtm, the Case Label for each test case is defined in the Case Setup window in GT-ISE. The Case Label is used to distinguish the different cases when the case combining macros are used to create a plot. The data set names can be changed manually after the plots are made if necessary.

1.14 Other Plotting Options

One built-in option for organizing multiple GX and GU files is the Tile for Plotting mode. This can be accessed through the toolbar button or the corresponding button at the top of the GX file. In this mode, the maps for all GX files are hidden, and the screen is divided between the GX and GU files on the left, and the plot window on the right. In addition, opened GX files will be tiled in the upper left hand side, while new GU files will be tiled in the lower left hand side.

Another option is separating the Plot Window from the GT-POST window. The External Plot Window button is located in the upper right hand corner of the plot window, and also in the Window menu.

This option is especially useful for multiple monitors; the plot window can be on a separate monitor from the plot tree and map view.

When in Tile for Plotting mode or the Plot Window is an external window, the option to automatically view plots from the tree is available. This can be activated in Tools > Options > Plot/Table Viewing or from the toolbar button .

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Plots can also be viewed from the GT-ISE style map, RLT Contour Map, or Animation Map. Right- clicking on a part will show the instantaneous or RLT plots for the selected part.

1.15 RLT Contour Map

The RLT Contour Map is used to visualize results in various components of the model. To open the RLT Contour Map, click the button in the GX file as shown in Figure 21.

Figure 21: The RLT Contour Map view.

This will switch the GT-ISE style map to a detailed map view of the engine model with calculated results shown on the map using both numbers and color. If desired, the plot tree can be hidden from view using the button at the top of the tree. In the contour view toolbox, there are options to change the RLTs displayed along with the contour range. The units can be changed in the Unit dropdown menu.

Results are available not only for pipes and flowsplits, but also for connection objects. This will show the color-contoured results over the pipes or at the connections. This option can be changed using the drop-down menu at the top of the contour view toolbox.

Contour Map

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Figure 22: The part output dialog for the EngineCrankTrain.

1.16 Animated Displays

GT-POST can also display an animated display of the values in the model. The Animation display shows instantaneous RLTs as the model completes one cycle, giving detailed information throughout the cycle.

Note that animation data is only stored for the model if the Number of Animation Points is defined in Run > Output Setup > Flow in GT-ISE. To launch the Animation display, click the animation button at the top of the GU window, next to the RLT Contour Map button. Similar to the RLT Viewer, there are variables and case options on the left side along with a color-coded legend of the results. Select Pressure, and the window will look similar to Figure 23.

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Figure 23: Display of the Engine Model in the Animation Window

The results are viewed by pressing the play button at the bottom-center of the screen. The colors are continuously changing as the values shift through the model, and the speed of the display can be altered using the bar on the left hand side.

1.17 Transient Example

The previous models used in the example were all steady state models, yielding steady state data averaged for a given engine speed. In this section, a transient model is used to generate data varying with respect to time. The example model used is the SI_4cyl_Imposed_Speed_Transient.gx found in the

%GTIHOME%\v7.x.0

\examples\Engine_1D_Gas_Exchange_Combustion\Transient\Imposed_Speed_Transient folder. In this example, the Time RLT Storage Multiple attribute is already defined as a value of 1 in the RLT- Output tab of the Output Setup window. This specifies the period interval to store the Time RLT data for the simulation, which can be accessed in GT-POST. For this section the Volumetric Efficiency and Brake Power will be plotted with respect to time for case 2 of the model.

1. From GT-ISE, open the example SI_4cyl_Imposed_Speed_Transient.gtm and run the simulation.

2. Once the simulation is finished, press the GT-POST icon on the toolbar and open the

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1. Open the TimeRLT tab, and select case 2 as shown in Figure 24.

2. Find the Engine under the EngineCrankTrain.

3. Expand the Flow folder and select the Volumetric Efficiency, Air data. The plot should look similar to Figure 25.

4. Do the same for Brake Power (HP) in the Torque/Power folder. The plot should look similar to Figure 26.

Figure 24: The Time RLT tab and case number box in the GX window.

Figure 25: The Time RLT plot of Volumetric Efficiency.

Time RLT Tab

Case Number

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Figure 26: The Time RLT plot of Brake Power (HP).

1.18 Conclusions

This tutorial covered creating and editing plots, as well as importing data from various sources.

Comparing data between similar models was illustrated, and animations and transient models were briefly discussed. This tutorial was intended to give a new user an introduction to some of the features available in GT-POST, for more detailed explanations of the program functions please see the GT-POST user manual located in the %GTIHOME%\v7.x.0\documents\Graphical_Applications folder.

GT-POST Tutorials GT-SUITE

GT-SUITE