.3 Tutorial 3
Tutorial 3 introduces the Optimize utility available within the Virtual Engines environment. At the conclusion of this tutorial you will be able to create an Optimize simulation, monitor the progress of the optimization and compare the optimized engine with the base engine.
1.3.1 
Creating an Optimize
An Optimize is a special form of a test-procedure that allows a Design of Experiments (DOE) to be performed on a base engine model. The user specifies:
· The goal of the experiment, which can be either to maximize or minimize any single performance characteristic
· The engine parameters that can be changed by the experiment.
The optimization process starts by calculating the value of the goal function for the base engine. It then proceeds by assessing quite large changes to each variable. The value of the goal function for each new engine is compared to the base engine and if the goal has improved then the process is repeated from the new best engine. This process continues until no more improvement can be made. Consequently, the number of engines that an Optimize will create is not predefined, but is a function of the size of the design space and the resolution to which each variable can be optimized. The user defines these parameters at design time.
In Simulation Explorer, right-click on engine ‘4 cylinder – 600 cc – restricted intake – 100 mm Intake’ as shown in Figure 3-1. Select New Optimize from the popup menu.
Figure 3-1: Select engine for New Optimize
The engine is loaded into Design with a new Optimize test-procedure as shown in Figure 3-2. Note that the test-procedure now includes an Optimize node. The rest of the test-procedure is identical to a conventional Speed Hook.
Figure 3-2: New Optimize in Design
Right-click on Speed Hook beneath the Test-Procedure and select Design from the popup menu. Enter 5000 for the Start RPM, 10000 for the End RPM and 1000 for the RPM Increment. Click on the Simulation tab and select SimLev5B from the dropdown list beside Simulator Name. Click on the Fuel tab and select Unleaded from the dropdown list beside Fuel. Click the Close button when done.
Right-click on Reference Ambient beneath the Test-Procedure and select Design from the popup menu. Enter 20 for the Reference Temperature and Click the Close button.
Right-click on Reference Throttle beneath the Test-Procedure and select Design from the popup menu. Enter 0.85 for the Area Ratio and Click the Close button.
Right-click on Optimize beneath the Test-Procedure and select Design from the popup menu as shown in Figure 3-3. Verify that the remainder of the Test-Procedure appears as shown.
Figure 3-3: Designing the Optimize
The Optimize Design window opens and the Goal tab is displayed (Figure 3-4). The default goal is Maximize Brake Power. Click on BMEP in the Available Goals list as shown in Figure 3-5.
Figure 3-4: Optimize goal
Figure 3-5: Select BMEP for Optimize goal
Click the Select button. The Optimize Goal Settings window, Figure 3-6, is displayed. In this optimize we will Maximize BMEP. Maximize is selected by default so click the OK button.
Figure 3-6: Select Maximize BMEP
The Goal tab should now appear as shown in Figure 3-7.
Figure 3-7: BMEP selected as Optimize goal
No comments:
Post a Comment