Yuan Xin


Future space missions by NASA that include Space Transfer Vehicles (STV) are ex pected to perform orbital transfers such as Lunar and Mars transfers and descents. STV requires deep-engine throttling thrust capability. To accomplish this, turbopumps employed in the Space Transfer Vehicles should efficiently provide a wide range of flow output. The current state-of-the-art cryogenic fuel and oxidizer turbopump designs with vaned diffusers do not perform efficiently at off-design (low) flow rate, mainly due to flow separation and stall in the vaned diffuser. This thesis evaluates the effectiveness of boundary layer control by wall suction for suppressing or eliminating the flow separation in the vaned diffuser of a turbopump. It presents the results of a three- dimensional diffuser model including the vaneless diffuser, vaned diffuser and turning channel using CFD code FIDAP and k e turbu lence model. The diffuser model was first studied at design flow condition using liquid hydrogen as the working fluid. Then the diffuser model was studied at off-design flow conditions also using liquid hydrogen as the working fluid, and suction was applied at the vaned diffuser at off-design flow rates. In this more complex and realistic computational model, the separation occured at the bottom plane of the vaned diffuser and at the top plane of the vaneless diffuser at off-design flow rates. Results show that suction applied at the bottom surface of the vaned diffuser can successfully eliminate flow separation at this location and increase the pressure recovery by 10% to 30% with varying wall suction rates. It also shows that there is a relationship between the off-design flow rate and the amount of wall suction required to effectively reduce or eliminate separation.

Library of Congress Subject Headings

Turbomachines--Diffusers; Turbomachines--Fluid dynamics; Turbine pumps; Space vehicles

Publication Date


Document Type


Department, Program, or Center

Mechanical Engineering (KGCOE)


Ogut, Ali

Advisor/Committee Member

Nye, Alan

Advisor/Committee Member

Venkataraman, P.


Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works. Physical copy available through RIT's The Wallace Library at: TJ267.5.D4 X56 1996


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