Investigation of Boundary Layer Transition and Separation in an Axial Turbine Cascade Using Glue-On Hot-Film Gages

Abstract

Experiments were conducted with glue-on hot-film gages in a large-scale axial turbine cascade to identify transition and/or separation on the suction surface of the blade. Standard strain-gage type temperature sensors were adapted and used as the gages and Transition and separation were identified by examining the mean and * Presently at Dresser-Rand,

An Experiment on Unsteady Flow Over an Oscillating Airfoil

“…It is known that the values of the constants A, B in the above relation are difficult to determine quantitatively (e.g. Vijayaraghavan and Kavanagh, 1988). In the present experiment no calibration was attempted.…”

Effect of Free-Stream Turbulence, Reynolds Number, and Incidence on Axial Turbine Cascade Performance

“…As mentioned previously, details on transition measurements using glueon hot-film gages are presented in a separate paper. For complete test results on all flow conditions tested, see Vijayaraghavan (1987). Figure 3 shows the measured static pressure distribution for the three inlet flow angles.…”

“…In the first, the Abu-Ghanaam and Shaw and Dhawan and Narasimha models, herein referred to as AGS and DN respectively, were used. In the second method, the actual transition points and transition lengths obtained from hot-film gage results were used (see Vijayaraghavan and Kavanagh, (1988) for details on the use of hot-film gages to determine transition start and end points of the airfoil suction surface). On the pressure surface, due to the laminar separation bubble close to the leading edge for all three inlet flow angles, no laminar-turbulent calculations were possible; hence, a fully turbulent calculation from the stagnation point onwards was made for all the test cases.…”

“…As an attempt to measure the profile losses and to obtain detailed transition data on a typical blade surface, a highly-loaded, high-turning angle, largescale turbine cascade was tested over a range of Reynolds number, turbulence level and incidence angle. Transition measurements were made on the blade suction surface using glue-on hot-film gages, and were supplemented with surface oil-flow visualizations (see Vijayaraghavan and Kavanagh (1988) for a detailed discussion of these measurements and comparisons). In addition, detailed five-hole pressure probe traverses were carried out in an exit plane of the cascade to determine the profile losses.…”

“…axial chord -8.0 in (203 mm) pitch/chord ratio -1.12 airfoil metal inlet angle,(from tangential)-38.0 °a irfoil metal exit angle, (from tangential)-23.7 °T he test cascade pack consisted of five blades with an aspect ratio (span/axial chord) of 1.25. Details on the design and fabrication of the test cascade and the test facility can be found in Vijayaraghavan, (1987). Testing was done at three inlet flow angles ( 41 = 45 0 , 52° and 38° as measured from tangential), four inlet turbulence levels (Tu = 0.8%, 2.0%, 4.8%, and 6.4%) and three Reynolds numbers (700,000, 540,000, and 330,000 based on axial chord and exit velocity), resulting in a total of 36 test flow conditions.…”