ELEMENT DESIGN AND DEVELOPMENT OF SMALL CENTRIFUGAL COMPRESSOR. VOLUME 1

• Main Authors: Welliver, A D, Acurio, J
• Format: Report
• Language: English
• Subjects: AIRFOILS; BEARINGS; CASCADE STRUCTURES; CENTRIFUGAL COMPRESSORS; COMPRESSOR ROTORS; DIFFUSERS; DUCT INLETS; GAS FLOW; GAS TURBINES; Hydraulic and Pneumatic Equipment; IMPELLERS; PERFORMANCE(ENGINEERING); PRESSURE; TEMPERATURE; TURBINE BLADES; TURBOJET ENGINES; VELOCITY

The purpose of this research program was to define, by analysis and experimental evaluations the design criteria and performance characteristics of a high-pressure-ratio, single-stage centrifugal compressor. The overall performance target was a pressure ratio of 10:1 at an efficiency of 80 percent and at an airflow rate of 2.0 pounds per second. The research was expected to lead to development of advanced technology, applicable to small gas-turbine engines. The research plan was to design 4 impellers and 4 diffusers using the best available knowledge. The components were to be tested and the design methods evaluated. Further tests were to be conducted with modified components to evaluate improvements in the design methods and add to the basic understanding. Each impeller was designed to provide a total-to-total pressure ratio of about 13:1 at a tip speed of 2000 fps, resulting in an absolute Mach number leaving the impeller of about 1.3. The inducers were designed with inlet-relative Mach numbers from 0.95 to 1.23, and the selected impeller diameters were from 6.0 to 8.0 inches. The diffusers were designed to match the impeller discharge Mach number of 1.3. Water-table studies were conducted with diffuser models to develop preliminary evaluations of the flow characteristics. Four diffuser models were selected for test with the same impeller. The diffuser test rig was instrumented with schlieren photography to evaluate the shock system of the diffuser. Diffuser models were designed to vary vaneless- space-diameter ratio, throat Mach number and throat area for investigating flow behavior and variable-airflow-capacity as a means of improving part load fuel consumption. See also Volume 2, AD0384924.