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Progress of High Efficiency Centrifugal Compressor Simulations Using TURBOThree-dimensional, time-accurate, and phase-lagged computational fluid dynamics (CFD) simulations of the High Efficiency Centrifugal Compressor (HECC) stage were generated using the TURBO solver. Changes to the TURBO Parallel Version 4 source code were made in order to properly model the no-slip boundary condition along the spinning hub region for centrifugal impellers. A startup procedure was developed to generate a converged flow field in TURBO. This procedure initialized computations on a coarsened mesh generated by the Turbomachinery Gridding System (TGS) and relied on a method of systematically increasing wheel speed and backpressure. Baseline design-speed TURBO results generally overpredicted total pressure ratio, adiabatic efficiency, and the choking flow rate of the HECC stage as compared with the design-intent CFD results of Code Leo. Including diffuser fillet geometry in the TURBO computation resulted in a 0.6 percent reduction in the choking flow rate and led to a better match with design-intent CFD. Diffuser fillets reduced annulus cross-sectional area but also reduced corner separation, and thus blockage, in the diffuser passage. It was found that the TURBO computations are somewhat insensitive to inlet total pressure changing from the TURBO default inlet pressure of 14.7 pounds per square inch (101.35 kilopascals) down to 11.0 pounds per square inch (75.83 kilopascals), the inlet pressure of the component test. Off-design tip clearance was modeled in TURBO in two computations: one in which the blade tip geometry was trimmed by 12 mils (0.3048 millimeters), and another in which the hub flow path was moved to reflect a 12-mil axial shift in the impeller hub, creating a step at the hub. The one-dimensional results of these two computations indicate non-negligible differences between the two modeling approaches.
Document ID
20170002701
Acquisition Source
Glenn Research Center
Document Type
Technical Memorandum (TM)
Authors
Kulkarni, Sameer
(NASA Glenn Research Center Cleveland, OH United States)
Beach, Timothy A.
(Vantage Partners, LLC Cleveland, OH, United States)
Date Acquired
March 30, 2017
Publication Date
March 1, 2017
Subject Category
Aircraft Propulsion And Power
Fluid Mechanics And Thermodynamics
Report/Patent Number
GRC-E-DAA-TN31275
NASA/TM-2017-219418
E-19315
Funding Number(s)
WBS: WBS 664817.02.03.02.03.01
CONTRACT_GRANT: NNC12BA01B
Distribution Limits
Public
Copyright
Public Use Permitted.
Keywords
turbomachinery
computational fluid dynamics
centrifugal compressors
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