AIR-PERFORMANCE EVALUATION OF A 4. 0-INCH-MEAN-DIAMETER SINGLE-STAGE TURBINE AT VARIOUS INLET PRESSURES FROM 0. 14 TO 1.88 ATMOSPHERES AND CORRESPONDING REYNOLDS NUMBERS FROM 2500 TO 50, 000

摘要

A 4.0-inch-mean-diameter turbine was investigated experimentally in air over a range of inlet pressure from 0.14 to 1.88 atmospheres, which corresponds to a Reynolds number range from about 2500 to about 50,000. The peak efficiency from high to low Reynolds number varied by a ratio of about 2 to 1, and the blade- to jet-speed ratio at which peak efficiency occurred also varied by a ratio of about 2 to 1. Below a Reynolds number of 24,000, the data indicated that the turbine could operate at several efficiencies at a given blade- to jet-speed ratio because of varying degrees of flow separation at the rotor outlet. At Reynolds numbers below 7000, in some instances, the flow at the rotor outlet tended to attach to the blade because of improved reaction across the rotor.nThe stator discharge coefficient varied from 0.98 to 0.86 for this range of Reynolds number. Even though a large change in loss occurred within the stator, the flow did not deviate appreciably from its design angle until a Reynolds number of approximately 5000 was reached.