Importance of FRM Converter & FRM Builder tools in GT-SUITE

Title: Importanceof FRM Converter & FRM Builder tools in GT-SUITE

Objective: 1. Explore tutorial SI_4cyl_GDI_Turbo by use of FRM Coverter 

                2. Build FRM Model for following configuration using FRM builder approach

 

Theroy:

What is FRM?

          Fast Running Engine Models are dynamic, fully-physical engine models that are designed specifically to run fast. While high-fidelity engine models are commonplace in the engine performance department, they are often too slow running to incorporate into system level models where long transient events may be simulated, or where the simulation model must respond faster than real-time, such as for HiL (Hardware-in-the-Loop) simulations. When simulation speed is of priority, high-fidelity GT-POWER engine models can be simplified into FRMs using a standard conversion process. It is up to the user how far to simplify the model, depending on the accuracy-vs.-runtime requirement.

What Actually  does FRM? 

FRMs are able to achieve such fast run times by two means: (1) increasing the simulation time step size, and (2) decreasing the number of calculations per time step. These two means are often accomplished at the same time by lumping various flow volumes together which will reduce the total number of subvolumes and also allow for a larger time step size by increasing the effective subvolume length (which is responsible for the time step size). In addition to simplifying and combining flow volumes, there are additional solver options that can reduce the number of calculations per time step and, thus, further decrease the run time without changing the time step size.

                    This tutorial covers the process of creating a Real-Time capable Fast Running Engine Model from a detailed, high-fidelity engine model. While this tutorial shows a specific set of steps, note that each engine model is unique and so the steps required to convert a detailed model will depend on the complexity of the model, as well as on the goals of the end user. For certain applications, such as Vehicle Thermal Management where engine coolant heat rejection must be maintained, the procedure may differ slightly in order to maintain certain key results

CASE 1: FRM CONVETER

                  There is use of 4 Cylinder GDI Turbo model for conversion in to FRM Model by use of FRM Converter

Find the tutorial by folowing path

'File' -> 'Examples' -> 'Engine_1D_Gas_Exchange_Combustion' -> 'Gasoline' -> 'SI_4cyl_GDI_Turbo'.

About model

This model is a 4-cylinder 2.0 liter turbocharged Gasoline Direct Injection (GDI) engine. The turbine wastegate is being dynamically controlled in order to target BMEP. A full-load speed sweep is being simulated, from 5000 RPM down to 1000 RPM. A semi-predictive charge air cooler is included such that the outlet temperature is predicted as a function of inlet gas temperature and mass flow rate, coolant temperature, and charge air cooler effectiveness.

                          

Launch FRM Tags
With the high-fidelity engine model open in GT-ISE, go to the Tools tab and click on 'FRM Tags'. The model has already been tagged.      

    Launch the FRM Converter
The GT-SUITE FRM Converter is a tool that will track the FRM Conversion process, organize all model files automatically within subdirectories, and provide result comparisons of key RLTs throughout the conversion process. The process information is stored in a *.frm file which can be saved and reloaded at any time to review the process or to continue where you left off.

With the high-fidelity engine model open in GT-ISE, go to the Tools tab and click on 'FRM Converter'. This will prompt you to create an FRM Conversion Project. It will validate the tagged subsystems and report if the validation is successful. Confirm that the correct model is specified in "Select the Baseline Detailed Model" per below, then click Next.

          

The open model will be reloaded in order to assure no changes were made before starting the conversion; click "OK". If the results are ready, you will get a message indicating the results file has been detected; click "Next". If the results are not yet ready and a message indicates this, click "Back", wait for the simulation to finish, then click "Next" and "Next" again once the results file is properly identified

                          

Step 1: Exhaust Manifold

The FRM Converter should now be at the Model Reduction page, as shown below. It is now time to start simplifying the first subsystem of the model. It is most efficient to start by simplifying the subsystem that is currently restricting the time step. For high-fidelity models, this is almost always the exhaust manifold where the highest gas velocities occur, which in turn restricts the time step. For Step Name, type "Exhaust Manifold". Select Exhaust Manifold 1 from the Tagged Subsystems list.

from the "Home" tab, click on "Run Setup" and go into the "FlowControl" folder, then double-click on the "ExplicitControl" green text within the "Time Step and Solution Control Object" attribute to edit the ExplicitControl reference object. Set "Maximum Time Step" to 720, then click "OK", and "OK" again to close Run Setup.

Click "Expand" on the FRM Converter to expand the Model Reduction page. The Exhaust Manifold will now be simplified. Make sure that the "Apply Smart Calibration Settings" check box is selected.

       

If accuracy is of higher importance than run-time, choose the "Simplify for Accuracy" option. This will combine the Exhaust Ports/Runners together, and left separate from the manifold volumes.

                                              

Clicking on the "Simplify Manually” tab will allow to manually simplify geometry for parts that were not tagged or where a different combination of volumes is desired.

Its value will be set to 300mm. Port Heat Transfer dominates vs. Runner Heat Transfer, therefore a parameter for the heat transfer multiplier called [HTM_Exhaust_Manifold_1_Step_1] will be.

This parameter will be used to calibrate heat transfer in the combined volume to assure the Turbine Inlet Temperature is maintained

To check the created parameters, launch Case Setup from the toolbar. Note that this Heat Transfer Multiplier parameter will be calibrated to match the Turbine Inlet Temperature, and so a value of 1 is simply used as an initial guess.

 Click "Next (Calibration)". Note that by default, the simplified model will be preprocessed in order to assure it is ready to run before setting up calibration. Once preprocessing is complete, close the preprocessing window to progress to the Calibration page.

 

Click "Configure Calibration" to open up the Design Optimizer settings. Make sure "Target" is selected for "Objective". Use the value selector for Response RLT and browse to and select "Massflow-Averaged Inlet Temperature" from the Turbine part, as shown below:

                         

Go into the "Factors " tab to define the factor along with the Lower and Upper values for the Range, and finally the Resolution. See the screenshot below for the appropriate values. Note that the [HTM_Exhaust_Manifold_1_Step_1] parameter is automatically placed into the first column. A different parameter can be selected if desired using the value selector.

          

Click OK in the Design Optimizer dialog, then finally click "Run calibration…" from within the FRM Converter and run the simulation. Once the optimization run is completed, close the simulation window and then click "Next" to go to the Results page. Note that the optimized parameter value has been automatically placed back in the model, and all of the original cases turned back On. Therefore, from the Results page, click "Run Model" to run the complete set of cases using the optimized value

Once the Step 1 results model has finished running, close the simulation window and click "Populate Accuracy RLT Table Below" to see a comparison of results for the RLTs which includes specified tolerances. If any tolerance is outside of the specified range, the tab will show a "!" indicator, and the text of the cell which contains an error outside of the specified tolerance will show up as red.

 Click "Open Key RLT Plots in GT-POST" to launch an automatically-generated Report File (*.gu file) containing plots of (1) "Accuracy Requirements Check" for each RLT with a specified tolerance, (2)."Calibration Check" showing results for the calibration performed, (3) "Full Results" showing a comparison of all of the Key RLTs, and (4) "Simulation Run Time" showing a comparison of the Factor of Real-Time and average time step sizes.

Step 2: Exhaust Pipes
For the second step of model simplification, the exhaust pipes downstream of the turbine will be simplified. Name the step "Exhaust Pipes". Select Exhaust Pipes 1 from the Tagged Subsystems list. Click on "Simplify for Accuracy" and click "Yes" for the "Delete Part" dialog

              

Since the pipe at the outlet of the Turbine is rather short (70mm), this pipe will be combined with the Catalyst volumes into a single FlowSplit part, see the "Simplify Manual" tab for instructions. Select the EP1_Pipe1-1 pipe along with the EP1_PDrop1-1 FlowSplit and the OrificeConn between them, then right-click on the selection and launch the Combine Flow Volumes Wizard.

    

Once in the Combine Flow Volumes wizard, keep "Combine flow volumes to Flowsplit" selected and click "Next" through the wizard until the last page, "Object Attribute Definition and Object Naming". Select "EP1_PDrop1-1" at the top of the dialog, then set the object name to "CAT". The Thermal tab shows that inputs are missing. We are dealing with it later, click "Finish". Hit Close in the "Combine Volume Wizard Report".

    

  

    

 

   

                                                                       

Open up the "CAT-1" part and go to the Thermal tab. Select the radio button for "Imposed Wall Temperature". Edit (double Click) the "GasT" Reference Object. Use the value selector for the "Wireless Signal or RLT (X)" object value and replace "tav:catconn1" with "tav0:CAT-1” and click "OK". Close the object dialog for the "CAT-1" part as well.

                  

Lastly, we need to Open Case Setup and set the value of [DIA_Exhaust_Pipes_1_Step_2] to 40 mm. This is only an initial guess, and will be used to calibrate the Turbine Outlet Pressure. In the FRM Converter, click "Next (Set Calibration)".

In the Calibration page, select Case 1 for calibration. Under "Configure calibration…", set the Response RLT to the Turbine Massflow-Averaged Outlet Pressure (trb-poa:Turbine), and set the lower and upper values of the range of DIA_Exhaust_Pipes_1_Step_2 at 35 and 45 mm, respectively.

                       

 

       

Step 3: Intake Manifold
Name the step "Intake Manifold". Select Intake Manifold 1 from the Tagged Subsystems list. Click on "Simplify for Accuracy". Click "Yes" on the Delete Part dialog; this will be handled later. Collapse the FRM Converter to provide space to work in the model map

                                    

 

Step 4: Compressor Outlet Pipes
Name the step "Compressor Outlet Pipes". Select Boost Pipes 1 from the Tagged Subsystems list. Click on "Simplify for Accuracy". Collapse the FRM Converter to provide space to work in the model map.

                                 

                                                       

                     

                            

 

 Step 5: Intake Pipes
Name the step "Intake Pipes". Select Intake Pipes 1 from the Tagged Subsystems list. Click on "Simplify for Accuracy". Collapse the FRM Converter to provide space to work in the model map.
Go into Case Setup and set the value of [DIA_Intake_Pipes_1_Step_5] to 45 mm (this is just an initial guess).

 

Step 6: Additional Changes
Name the step "Additional Changes". Select Exhaust Manifold 1 from the Tagged Subsystems list. Click on "Simplify for Speed

Click "Next (Calibration)" to preprocess the model and continue to Calibration.In the Calibration page, leave all cases enabled for calibration. This may take some additional time to calibrate vs. only calibrating for Case 1, but it will result in better accuracy across all operating conditions. Under "Configure calibration…", change the Response RLT to the Turbine Massflow-Averaged Inlet Temperature (trb-tia:Turbine). Set the lower and upper values for HTM_Exhaust_Manifold_1_Step_6 of the range at 0 and 2, respectively. Set the Resolution (% of Range) to 1.

Run the calibration, and once it is finished, click "Next".In the Results page, click "Run Model" to rerun the full set of Cases. Check the model results and assure that they are satisfactory. The model should now be running around 1 xRT. In the FRM Converter, click "Next (Begin Next Step)".

Step 7: Cylinder Slaving
The final simplification to the model will utilize the Cylinder Slaving capability of the EngCylinder component. Name the new step "Cylinder Slaving", then collapse the FRM Converter to provide space to work in the model map.

Right-click on any of the EngCylinder parts on the map and choose "Edit Parent Object". Go to the "Advanced" tab and for "Cylinder Slaving Option", select "slave-RT-full-v2018", then click OK. Now double-click on Cylinder-01, go to the "Advanced" tab, and set the Cylinder-01 override value of "Cylinder Slaving Option" to "master".

For the full cylinder slaving to function, each Valve must be specified as either an Intake or Exhaust valve. Find the ValveCamConn template in the model tree on the left and select "Edit Parts in Spreadsheet" view. The intake and exhaust valves are easy to distinguish. The intake ones start with "IM1_PortRun” and the exhaust ones start with "EM1_PostRun". Go to the Output folder and set "Valve Type for RLT Variable Calculations" to "intake", respectively "exhaust".

Step 8: Real-Time Solver (optional)

Click "Next (Begin Next Step)" in the FRM Converter. Name this new step "Real-Time Solver", then collapse the FRM Converter. To run with the real-time solver, the license type of the model must be changed. However, certain templates are not allowed with the real-time solver, and so they must first be removed from the model.

 

 

CAE 2. FRM Builder Approch

Architecture type is Compression ignition engine select

                

Insert the Engine specification 

                         

Turbo type is Twin scroll

                  

Engine type is 6 Cylinder 

                            

Control Logic type is GT Suite Controller

                         

FRM Builder model

                                      

case 1-5 Result

 

 

Case 6-10

 

 

Case 11-15

Case 16-20

 

Case 21-25

 

Overall conclusion

1.FRM is fast runing model & take very less time to run the model

2. Understand the process of FRM Conveter for conversion of detailed model in to FRM

3. Understand the FRM Converter process & solve the all cases