Masters Theses

Date of Award

12-1996

Degree Type

Thesis

Degree Name

Master of Science

Major

Mechanical Engineering

Major Professor

Roy J. Schulz

Committee Members

Robert Roach, John Caruthers

Abstract

As modern aircraft gas turbine engines push their operational envelopes, stable aerodynamic operation is imperative. The engine compression system is particularly vulnerable to changes in flight conditions. Non-uniform flow conditions may cause adverse reactions in the compressor in the form of surge or stall. Numerical simulations can be used to predict engine and component performance and operability under such adverse conditions. These simulations can be used to investigate events and conditions not easily reproduced in ground test facilities as well as reduce the amount of expensive testing required in such facilities. A true three-dimensional compression system model would greatly increase the accuracy of predicted compressor performance and operability and could yield a better understanding of flow interactions within the compressor. A new three-dimensional compression system simulation was constructed by coupling the three-dimensional Navier-Stokes flow solver, NPARC, with source terms that model the effects of turbomachinery components. A stage-by-stage characteristic technique adapted from the one-dimensional compressor code, DYNTECC, was used to calculate the turbomachinery source terms. This thesis discusses the development, adaptation, and implementation of the stage characteristic approach for calculating sources used in NPARC. The distribution of the source terms from the one-dimensional domain to the three-dimensional domain is presented, and an investigation of the radial distribution of the sources during pre-stall compressor performance was conducted. A simple compressor, consisting of a single transonic rotor, was modeled because data was available for it. Through this investigation, it was discovered that the radial distribution of the turbomachinery source terms was important for obtaining accurate radial profiles of the flow field but was less influential on the overall compressor performance in terms of overall total pressure ratio and efficiency. The adaptation of the stage characteristic approach within a three-dimensional flow solver was shown to be a viable method for three-dimensional modeling of a compression system.

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