| Summary: | 碩士 === 國立成功大學 === 航空太空工程學系 === 83 === The purpose of this study is to investigate the effect of
turbulence on the development of boundary layer on the
turbine cascade. The freestream turbulence was controlled by
three different kinds of grids, characterized by the
turbulence intensities, ranging from 1.6% to 5.0%, and the
integral length scales, ranging from 4.69mm to 9.55mm.
Experiments were conducted in a low speed wind tunnel,
including (1)the calibration of inlet flow uniformity,
flow periodicity, and two-dimensionality, (2) surface oil
flow visualization, (3)measurements of surface pressure
distribution, (4)measurements of total pressure loss and
deviation angle. Satisfactory flow quality was obtained
by controlling the end-wall bleeding, tailboards
arrangements, and sidewall suction rate. Measurements were
made at an inlet velocity of about 10.7m/s, corresponding
to the Reynolds number about 50,000 based on the blade
chord. Flow separation on suction side was found in all cases
studied. Higher the turbulence intensity further
upstream is the transition location occurred, resulting
into lower total pressure loss and exit deviation angle.
|
|---|
