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Chapter 9: Using a Single Rotating Reference Frame

This tutorial is divided into the following sections:

9.1.Introduction

9.2.Prerequisites

9.3.Problem Description

9.4.Setup and Solution

9.5.Summary

9.6.Further Improvements

9.7.References

9.1. Introduction

This tutorial considers the flow within a 2D, axisymmetric, co-rotating disk cavity system. Understanding the behavior of such flows is important in the design of secondary air passages for turbine disk cooling.

This tutorial demonstrates how to do the following:

•Set up a 2D axisymmetric model with swirl, using a rotating reference frame.

•Use the standard - and RNG - turbulence models.

•Calculate a solution using the pressure-based solver.

•Display velocity vectors and contours of pressure.

•Set up and display XY plots of radial velocity and wall distribution.

•Restart the solver from an existing solution.

9.2. Prerequisites

This tutorial is written with the assumption that you have completed one or more of the introductory tutorial Fluid Flow and Heat Transfer in a Mixing Elbow (p. 35) found in this manual and that you are familiar with the ANSYS Fluent tree and ribbon structure. Some steps in the setup and solution procedure will not be shown explicitly.

9.3. Problem Description

The problem to be considered is shown schematically in Figure 9.1: Problem Specification (p. 320). This case is similar to a disk cavity configuration that was extensively studied by Pincombe [1].

Air enters the cavity between two co-rotating disks. The disks are 88.6 cm in diameter and the air enters at 1.146 m/s through a circular bore 8.86 cm in diameter. The disks, which are 6.2 cm apart, are spinning at 71.08 rpm, and the air enters with no swirl. As the flow is diverted radially, the rotation of the disk has a significant effect on the viscous flow developing along the surface of the disk.