Incorporating bleed/leakage flow into a simulation

This article describes how to model bleed/leakage flow in an ADS simulation using an engine model definition file. 

Three types of leakage models are supported in Code Leo:

  1. Cavity model with knife edge seals
  2. Leakage flow in front of the airfoil leading edge
  3. Leakage flow at the back of the airfoil trailing edge

There are three steps to modeling leakage flow:

  1. Create the engine model definition file that specifies the bleed/leakage flow
  2. Add a pointer to this file in the Leo setup file
  3. Execute Code Leo

For more information on ADS engine models, please refer to the ADS Engine Model Reference in the Product Documentation section of the support portal.

Create an engine model definition file that describes the leakage flow

Incorporating a Cavity with Knife Edge Seals

1. Set IDLEAK or ODLEAK to 1

If you want to add a cavity at the inner diameter endwall, set IDLEAK to 1.  If you want to add a cavity at the outer diameter endwall, set ODLEAK to 1.

For example, if we want to model cavity bleed at the ID endwall, we need to set IDLEAK to 1:

2. Specify the details of the knife edge seal(s)

Once you've set IDLEAK or ODLEAK to 1, you'll now need to define the knife edge seal(s).  This includes the number of knife edge seals in the cavity (NS_KEDGE), the tip clearance of the knife edge seal (KEDGECLS), the radial location of the knife edge seal (KERADIUS) and the rotational speed (KERPM).  If IDLEAK is set to 1, provide this information in the *IDLEAK section (Division 4).  If ODLEAK is set to 1, provide this information in the *ODLEAK section (Division 5).

In our example, say we want to model cavity bleed at the ID wall.  The cavity contains 4 knife edge seals, each with a tip clearance of 0.5 inches and a radius of 270 inches.  The speed of the rotor at the cavity is 6,000 RPM in the colockwise direction looking downstream.

Since the cavity bleed occurs at the ID wall, the values for NB_KEDGE, KEDGECLS, KERADIUS and KERPM are placed in the *IDLEAK section (Division 4):

Save your engine model definition file and exit.  In this example, we'll call it ROW1-EMODEL.LIST.

Incorporating Leakage Flow in front of the Airfoil Leading Edge

1. Set IDLEAK or ODLEAK to 5

To add leakage flow in front of the leading edge at the inner diameter endwall, set IDLEAK to 5.  If you want this type of leakage flow at the outer diameter endwall, set ODLEAK to 5.

For example, to add leakage flow at the ID wall in front of the airfoil trailing edge, we set IDLEAK to 5:

2. Specify the amount of mass flow bleed

To specify the amount of mass flow bleed, you'll need tospecify the value for MASS-BLEED.  If the leakage flow occurs at the ID wall, set the value in *IDLEAK (Division 4).  If it occurs at the OD wall, set the value in *ODLEAK (Division 5).

Save your engine model definition file and exit.  In this example, we'll call it ROW1-EMODEL.LIST.

Incorporating Leakage Flow behind the Airfoil Trailing Edge

1. Set IDLEAK or ODLEAK to 6

To add leakage flow behind the trailing edge at the inner diameter endwall, set IDLEAK to 6.  If you want this type of leakage flow at the outer diameter endwall, set ODLEAK to 6.

For example, to add leakage flow at the OD wall in front of the airfoil trailing edge, we set ODLEAK to 6:

2. Specify the amount of mass flow bleed

To specify the amount of mass flow bleed, you'll need tospecify the value for MASS-BLEED.  If the leakage flow occurs at the ID wall, set the value in *IDLEAK (Division 4).  If it occurs at the OD wall, set the value in *ODLEAK (Division 5).

Save your engine model definition file and exit.  In this example, we'll call it ROW1-EMODEL.LIST.

Update the Leo setup file to recognize your leakage flow

Save your engine model definition file and update your corresponding Leo setup file to activate the negine model.  This is accomplished by setting EMODEL to 10 and adding two lines to the end of the file to point to your EMODEL definition file:

Save your Leo setup file and exit.

Execute Code Leo

With your configuration complete, simply invoke the solver and await the results of your run.


Code
Author
George Fan
Date Created
2013-06-21 07:47:32
Date Updated
2013-06-21 08:01:14
Views
4623