INVESTIGATION OF A SHROUDED AND AN UNSHROUDED AXIAL-FLOW SUPERSONIC COMPRESSOR

摘要

An unshrouded axial-flow supersonic compressor rotor has been designed based upon the experience gained through tests of the original shrouded rotor. A study of two-dimensional blade sections led to the attainment of thicker blades which alleviated the necessity of a shroud attached to the blade tips. A 16-inch-tip-diameter rotor was con¬structed and an investigation was made in Freon-12 gas at the NACA Langley Laboratory through a range of equivalent tip speeds from 866 to 1680 feet per second when converted to standard sea-level air. As designed, the unshrouded rotor produced a pressure ratio across the rotor of 2.03 with an efficiency of 83.5 percent at a weight flow of 28.0 pounds per second. Operating without inlet guide vanes, the rotor produced a pressure ratio of 2.20 at an efficiency of 8U.5 percent and a flow rate of 27.8 pounds per second. Reasonable agreement was obtained between test results and design values of the relative total pressure and Mach number at the exit of the blades.nTests results for an accurately fabricated model of the original shrouded rotor are presented for direct comparison with data obtained with the use of a similar rotor tested in air at the NACA Lewis Flight Propulsion Laboratory. At the design tip speed of 1610 feet per second, the shrouded rotor tested in Freon produced a total pressure ratio of 1.98 with 84-percent efficiency at a weight flow of 27.6 pounds per second of air, as compared with 1.93, 79 percent, and 25.8 pounds per second for the similar rotor in air. The differences are attributed to the fact that the flow into the blading was not entirely supersonic for the tests in air.