Week-7 : Converting a detailed engine model to a FRM model

Aim: 

• Explore tutorial number 9 and write a detailed report
• Build FRM Model for following configuration using FRM builder approach
• Run all cases

Tutorial 9:

Model:4-cylinder Turbocharged Gasoline Direct Injection engine with turbocharger wastegate controller and semi-predictive intercooler.

Description:

Turbo and Intercooler:

• The CompressorMapParam template is used to generate a fully extrapolated compressor map from a single design point using a set of physically based parametric equations.
• The IntercoolerEff compound is used to calculate the intercooler outlet temperature based on input mass flow vs effectiveness data.
• A torque part is used to model turbo total bearing friction torque.
• A turbo shaft inertia multiplier is used to impose a high inertia for the first 3 cycles, when flow is still stabilizing from the initial conditions. On cycle 4, the inertia multiplier is back to 1 and the wastegate controller starts actuating the wastegate diameter.

Intake System:

• Pipe diameters were modified to be realistic for a turbo intake system. The pre-compressor pipes have slightly larger diameters than the post-compressor pipes (due to the increased density after the compressor).
• With the increased post-compressor boost temperatures, the WallTempSolver was used to calculate the pipe wall temperatures and more accurately model pipe heat transfer.

 Exhaust System:

• A basic turbocharger exhaust manifold is used.
• WallTempSolver with stainless steel material properties (common for high exhaust temperature SI applications) is used in the exhaust.

Conversions:

Exhaust Manifold:The exhaust manifold takes common value and combine them into data in FRM conversion to reduce to reduce simulation time, and provide faster results.

Exhaust Pipes: The pipes connected to turbine are reduced steps by FRM Converter.

Intake Manifold:The intake manifold simulates by taking one volume and reducing that particular by eliminating steps.

Compressor Outlet Pipes: The outlet from Compressor to intercooler is eliminated and made it into a single model.

Intake Pipe: It is also get simplified.

Exhaust Pipe: Exhaust Port also get simplified by combine flow wizard.

Cylinder Slaving:Making the 1st cylinder as master cylinder rest are made slave to decrease the simulation time. Rest of the cylinder will follow the pattern of 1st one.

RLT Creator:The RLT creator was setup in the model and liscence has to be changed to GT-Power from GT-Suite because the unavailability of GT-Suite-RT.

Case Setup: All 5 cases are activated

Simulation duration Summary: The CPU Time is almost 2 times than actual timing of the process which is very less than the non-FRM model simulation time

FRM Builder Model

Specifications:

• Bore=102mm
• Stroke=115mm
• CR=17
• No of cylinders=6
• CI Engine
• Twin Scroll Turbine
• GT Controller

Steps:

Step1

Step2

Step3

Step4

Step5

Layout

Case Setup :All 25 Cases are activated

Simulation Time :The CPU Time is almost 3 times than actual timing of the process which is very less than the non-FRM model simulation time

Results

For 1-5 Case

Turbine

Compressor

For case 20-25

Turbine

Compressor

Conclusion:

• Most of the cases the targeted BMEP value is achieved .
• Higher load and BMEP leads turbine and compressor to operate at critical speeds which is not good in strength terms of view.
• The FRM Model gave a overall faster results as compared to normal simulation.