Title page for ETD etd-04292003-155208


Type of Document Master's Thesis
Author Langford, Matthew David
Author's Email Address mlangford@vt.edu
URN etd-04292003-155208
Title Experimental Investigation of the Effects of a Passing Shock on Compressor Stator Flow
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Ng, Fai Committee Chair
Dancey, Clinton L. Committee Member
Schetz, Joseph A. Committee Member
Keywords
  • Particle Image Velocimetry
  • Vortex Formation
  • Unsteady Losses
  • Rotor Bow Shock
  • Compressor Cascade
Date of Defense 2003-04-17
Availability unrestricted
Abstract
A stator cascade was developed to simulate the flow conditions within a close-stage-spacing transonic axial compressor. Experiments were conducted in a linear transonic blowdown cascade wind tunnel with an inlet Mach number of 0.65. The bow shock from the downstream rotor was simulated by a single moving normal shock generated with a shock tube. First, steady pressure data were gathered to ensure that the stator cascade operated properly without the presence of the shock. Next, the effects of the passing shock on the stator flow field were investigated using shadowgraph photography and Digital Particle Image Velocimetry (DPIV). Measurements were taken for three different shock strengths. In every case studied, a vortex formed near the stator trailing edge as the shock impacted the blade. The size of this vortex was shown to be directly related to the shock strength, and the vortex remained present in the trailing edge flow field throughout the cycle duration. Analysis of the DPIV data showed that the vortex acts as a flow blockage, with the extent of this blockage ranging from 2.9% of the passage for the weakest shock, to 14.3% of the passage for the strongest shock. The vortex was also shown to cause flow deviation up to 75° for the case with the strongest shock. Further analysis estimated that the total pressure losses due to shock-induced vorticity ranged from 46% to 113% of the steady wake losses. Finally, the total pressure loss purely due to the upstream-propagating normal shock was estimated to be roughly 0.22%.
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