Ph.D. Defense

Zhenhao Jing 

(Advisor: Prof. J.V.R. Prasad)
 

"Modeling and Simulation of Flow Transients inside a Multi-Stage Axial 
Centrifugal Compressor" 

Wednesday, March 20, 2024, 

11 a.m. 
MK 325 
MS Teams

Abstract 

Unsteady simulations of compressors remain of great interest in compressor design and analysis. While the three-dimensional Navier-Stokes solvers are computationally expensive, the reduced order model is still the backbone of tools supporting early design stages. Compressor mean line flow models are common tools for steady-state analysis and the design of multi-stage axial and centrifugal compressors. However, unsteady flow models using the mean line approach are not common. This study involves the development of an unsteady mean line flow model that features a series of physics-based modeling approaches to find compressor stages’ performance at every time step during unsteady simulation. This feature distinguishes the presented methodology from most existing unsteady compressor models using compressor characteristics as an input.  

By utilizing the developed unsteady mean line flow model, a series of steady-state and unsteady simulations are performed and presented. Sensitivity studies on selected loss models are presented for steady-state simulations to reveal their influence. During compressor rig tests, the flow transients are simulated to investigate the surge process and choke/unchoke response. A novel unsteady rig-test approach enabling measurement of equilibrium characteristics on the unstable side is proposed and simulated. In order to simulate compressor flow transient in real working conditions in a gas-turbine engine, a lumped-parameter combustor-turbine model is developed and coupled with the compressor model. Such an approach enabled the simulation of gas turbine transients, including fast engine acceleration/deceleration and heat transfer effects in those engine transients. A novel active energy management strategy, which uses an electric starter/generator (ES/G) to enhance gas turbine acceleration, is proposed and simulated. A similar approach using ES/G to assist recovery from surges is also examined by simulation, and the necessary ES/G power for such a task is evaluated. 
 

Committee 

• Prof. J.V.R. Prasad – School of Aerospace Engineering (advisor)
• Prof. Yedidia Neumeier– School of Aerospace Engineering
• Prof. Lakshmi N. Sankar – School of Aerospace Engineering
• Prof. Jechiel I. Jagoda – School of Aerospace Engineering
• Mr. Darrell K. James – Technical Fellow, Honeywell International Inc.