NDLI: Non-Axisymmetric End Wall Profiling in Transonic Compressors—Part II: Design Study of a Transonic Compressor Rotor Using Non-Axisymmetric End Walls

Content Provider	The American Society of Mechanical Engineers (ASME) Digital Collection
Author	Reising, Steffen Schiffer, Heinz-Peter
Copyright Year	2009
Abstract	Secondary flows involving cross flow at high stage loading in modern axial compressors contribute significantly to efficiency limits. This paper summarizes an approach to control end wall flow using non-axisymmetric end walls. The challenge is to find the optimal non-axisymmetric end wall shape that results in the largest gain in performance. An automated multi-objective optimizer connected to a 3-D RANS flow solver was used to design the end wall contour. The process chain was applied to the rotor hub end wall of Configuration I of the Darmstadt Transonic Compressor. Several optimization strategies involving different objective functions to be minimized and the corresponding performances were compared. The parameters considered within the optimization process were isentropic stage efficiency, pressure loss in the rotor, throat area and secondary kinetic energy (SKE). A parameter variation was undertaken, leading to the following observations: Strong penalties on SKE at the rotor outlet and moderate penalties on isentropic efficiency, throat area and pressure ratio led to the best design. Isentropic efficiency could be raised by 0.12%, SKE at the rotor exit was reduced while the total pressure ratio of the stage remained constant. Strong penalties on efficiency and pressure ratio, a moderate one on throat area and a small one on SKE at the rotor outlet all led to a smaller increase in efficiency: 0.06%. On the other hand, a slight raise in the total pressure ratio could be achieved. A third optimization, eliminating the restriction on the throat area, was carried out to see which benefit in performance could be achieved without this geometrical restriction. Since the throat areas of all optimized geometries differ slightly from the datum value, an estimation was derived to see the extent to which the end wall profiling and cross section enlargement contribute to the improvements. Finally, a method to display secondary flows in turbomachinery is introduced. A second CFD simulation is used to calculate the primary flow where the hub end wall is defined as an Euler wall to avoid the end wall boundary layer and so eliminate the cause for some of the secondary flow mechanisms. This method clearly shows how the characteristics of secondary flow can be positively influenced by using non-axisymmetric end walls.
Sponsorship	International Gas Turbine Institute
Starting Page	25
Ending Page	37
Page Count	13
File Format	PDF
ISBN	9780791848883
DOI	10.1115/GT2009-59134
e-ISBN	9780791838495
Volume Number	Volume 7: Turbomachinery, Parts A and B
Conference Proceedings	ASME Turbo Expo 2009: Power for Land, Sea, and Air
Language	English
Publisher Date	2009-06-08
Publisher Place	Orlando, Florida, USA
Access Restriction	Subscribed
Subject Keyword	Chain Computational fluid dynamics Rotors Turbomachinery Compressors Flow (dynamics) Pressure Optimization Design Cross-flow Simulation Reynolds-averaged navier–stokes equations Shapes Kinetic energy Boundary layers
Content Type	Text
Resource Type	Article

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