Cold-Air Performance of a Tip Turbine Designed To Drive a Lift Fan IV - Effect of Reducing Rotor Tip Clearance

摘要

Performance was obtained over a range of speeds and pressure ratios for a 0.4 linear scale version of the LF460 lift fan turbine with the rotor radial tip clearance reduced to about 2.5 percent of the rotor blade height. These tests covered a range of speeds from 60 to 140 percent of design equivalent speed and a range of scroll inlet total to diffuser exit static pressure ratios from 2.6 to 4.2.nThe results of the investigation showed that reducing the rotor tip clearance from 25 to 2. 5 percent of the rotor blade height resulted in an increase in total efficiency from 0. 815 to 0. 861. This represents a 5.6 percent increase.