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Chapter 4: Use of Parameterization to Optimize Fan Location
4.1. Introduction
The purpose of this tutorial is to demonstrate the following ANSYS Icepak features with the help of a
small system level model.
In this tutorial you will learn how to:
• Use network blocks as one way of modeling packages.
• Specify contact resistance using side specifications of a block object.
• Define avariable as a parameter and solve the parametric trials.
• Specify fan curves.
• Use local coordinate systems.
• Generate a summary report for multiple solutions.

4.2. Prerequisites
This tutorial assumes that you have little experience with ANSYS Icepak, but that you are generally familiar with the interface. If you are not, please review Sample Session in the Icepak User's Guide and the
tutorialFinned Heat Sink of this guide as some of the steps that were discussed in these tutorials will
not be repeated here.

4.3. Problem Description
The system level model consists of a series of IC chips on a PCB. A fan is used for forced convection
cooling of the power dissipating devices. A bonded fin extruded heat sink with eight 0.008 m thick fins
is attached to the IC chips. The fan flowrate is defined by a nonlinear fan curve. The system also consists
of a perforated thin grille. A study is carried out for the optimum location of the fan by using the
parameterization feature in ANSYS Icepak.

Release 14.5 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information
of ANSYS, Inc. and its subsidiaries and affiliates.

75

Use ofParameterization to Optimize Fan Location
Figure 4.1: Schematic of the Geometry

4.4. Step 1: Create a New Project
1. Start ANSYS Icepak, as described in Starting ANSYS Icepak in the Icepak User's Guide.
When ANSYS Icepak starts, the Welcome to Icepak panel opens automatically.
2. Click New in the Welcome to Icepak panel to start a new ANSYS Icepak project.
3. Specify a name for your project (i.e.,fan_locations) and click Create.
ANSYS Icepak creates a default cabinet with the dimensions 1 m × 1 m × 1 m, and displays the
cabinet in the graphics window. This cabinet will be modified in the next section.

4.5. Step 2: Build the Model
1. Resize the default cabinet.
The cabinet forms the boundary of your computational model. Press the isometric view icon ( )
for a 3D view. Select Cabinet inthe Model manager window and enter the location values as shown
in the panel below. The geometry window can be found in the lower right hand corner of the GUI.

76

Release 14.5 - © SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information
of ANSYS, Inc. and its subsidiaries and affiliates.

Step 2: Build the Model

Extra
The previous tutorial showed you howto enter these values in the Cabinet panel.

2. Create the Fan.
Click on the Create fans icon ( ) in the object toolbar next to the model tree to create a 2D intake
circular fan on one side of the cabinet. Change the plane to yz and enter the location values shown
in the geometry window below:

• Defining a parameter for multiple trials.
One of the objectives of this exercise is toparameterize the location of the fan. To create a parametric variable in ANSYS Icepak, input a $ sign followed by the variable name. Thus, to create
the parametric variable “zc,” type $zc in the zC box in addition to the other location values, and
click Apply. When ANSYS Icepak asks you for an initial value of “zc", enter an initial value of 0.1,
and click Done.
Figure 4.2: The Param value PanelWe will now set the physical properties that will define the fan behavior:
a. Edit the fan object and go to Properties tab.
b. In the Properties tab, retain the selection of Intake for Fan type and select Non-linear in the Fan
flow tab.
c. Enter the characteristic curve by clicking on the Edit button and selecting Text Editor in the dropdown list in the Non-linear curve group box.

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