Ph.D. Proposal: Zhenhao Jing

Fri Sep 24 2021 01:00 PM
Montgomery Knight Building 325
"Modeling and Simulation of Flow Transients inside a Multi-Stage Axial Centrifugal Compressor"

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Ph.D. Proposal

 

Zhenhao Jing

(Advisor: Prof. J.V.R. Prasad)

 

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

 

Friday, September 24
1 p.m.
Montgomery Knight Building 325

 

Abstract:
Quasi-1D mean line flow models are common tools for steady-state analysis and the design of multi-stage axial and centrifugal compressors. However, dynamic models of compressor flow using the mean line approach are not common. In axial compressors, the blade aerodynamic force distribution is perpendicular to the mean line, and the dynamic model would lack a force source term to balance the adverse pressure gradient. In this work, a dynamic 1D mean line model for axial-centrifugal compressor is proposed, where the blade rows, i.e. rotors and stators, are modeled as successive diffusing stream tubes in their own stationary or rotating reference frames. The geometry of the stream tubes considers the stagger angle of the blades. Adjacent stream tubes are connected by a double-side time-dependent boundary condition called a Compact Interface Element (CIE), which not only allows perturbations to propagate between the stream tubes, but also tolerates the discontinuity in flow properties caused by both the reference frame transformation and the losses associated with sudden flow turning and mixing. The energy is added into flow implicitly by reference frame transformations, thus the analysis of axial-compressor flow is independent of any aerodynamic force source term. The characteristics of a single blade row are predicted by the sudden flow turning model and mixing loss, which are functions of the incidence angle. The choke of a blade row is predicted by the flow turning at a negative incidence angle, which introduces a throat. The choke model is capable of simulating deep choke in compressor operations while multiple blade rows are choked at the same time. A lumped combustor-turbine model is developed to be coupled with the compressor model to simulate the dynamic response of a compressor in an engine configuration. By using the developed dynamic model, studies on the stability while acceleration under heat addition, as well as the tradeoff between the rate of acceleration/ deceleration and off-design performance are analyzed.

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 – Principal Engineer, Honeywell International Inc

Location

Montgomery Knight Building 325