SOME TESTS ON PARTIAL ADMISSION TURBINE CASCADES

The cascade tests described in this paper were performed to investigate the nature of flow in the rotor blade channels of axial flow turbines with partial admission. Three cascades of different pitch-chord ratios were tested for this purpose. The variation of the tangential force on the cascade for various positions was measured and compared with Stenning's analysis; the agreement between this analysis and the test points is good. The tests show that the tangential force on the cascade increases with the Reynolds number within the range (0·82 × 105 to 1·38 × 105) covered by the experiments. Direction and velocity profiles obtained behind the cascade at both ends of the sector showed the difference between the flows in the turbine blade cascades with full and partial admissions. Pressure distribution around the blades at both ends of the admission sector showed a marked departure from the normal full admission pattern. Measurement of the static pressure in the clearance space between the cascade and the inlet duct at the ends of the admission sector indicated the presence of suction" which varied with the position of the cascade relative to the admission sector. © 1969."