Space Transfer Vehicles (STV) are expected to perform missions (orbital transfer, Lunar/Mars transfer and descents) which will require deep-engine throttling thrust capability. To accomplish this, turbopumps which can efficiently provide a wide range of flow outputs are needed. The current state-of-the-art cryogenic fuel and oxidizer turbopump designs do not perform efficiently at off-design flow rates mainly due to stall and flow separation in the diffuser. This thesis examines how boundary layer control techniques can be used to control, reduce or eliminate diffuser flow separation. A finite element based code, FIDAP, was used to study flow in a diffuser by developing a 2-D diffuser model and establishing conditions for flow separation. Various rates of suction (removing decelerating fluid particles) and blowing (reenergizing decelerating fluid particles) were tested for their effectiveness in suppressing or eliminating the flow separation at an off-design flow rate. The results showed that FIDAP can be used effectively to model boundary layer control by suction and blowing in a diffuser operating at 60% of design flow. Suction was implemented at various flow rates through the top of the diffuser and shown to be effective at a rate of 15% in counteracting the incidence effects at the inlet of the diffuser and reduce the region of flow separation. Blowing was also shown to be effective in reenergizing the boundary layer to reduce the region of flow separation.

Library of Congress Subject Headings

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

Publication Date


Document Type


Department, Program, or Center

Manufacturing and Mechanical Engineering Technology (CAST)


Ogut, A.

Advisor/Committee Member

Torok, J.

Advisor/Committee Member

Veres, J.


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 W47 1991


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