Wake Passage Effects on the Losses in a Linear Turbine Cascade
AIR FORCE INST OF TECH WRIGHT-PATTERSON AFB OH SCHOOL OF ENGINEERING
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A linear turbine cascade was used to investigate the effects of wake passage due to stator-rotor interaction. The wakes were modeled by passing 1.98 mm 0.078 in diameter bars upstream of a linear cascade blade row. Total pressure loss coefficients, mass averaged total pressure loss coefficients and velocities were used to characterize the effects of wake passage. Bar passing frequencies of 80, 160, 320 barssec were tested. These frequencies were tested, with the bars at 6.35 mm 0.25 in intervals and at two Reynolds numbers, 341, 000 and 45,5000 Bar spacings of 12.7 mm 0.5 in, and 89 mm 3.5 in were also examined. For a bar spacing of 12.7 mm these tests were made at a Reynolds number of 45,5000 and bar passing frequencies of 80 barssec, 160 barssec, and with the bars stopped. The varying Reynolds numbers did not affect the results nor was there appreciable differences for the range of wake passing frequencies. However, for the same bar passing frequency, losses were effectively halved by doubling the spacing. The lack of influence of frequency and the effect of spacing was consistent with the time scale used. The maximum time scale reached was 0.95 so any influence due to changes in frequency were not felt in the blade passage. Whereas, for the same frequency, with half the bars, there were half the losses in the passage at any given time.
- Hydraulic and Pneumatic Equipment
- Fluid Mechanics