Unsteady Flow and Whirl-Inducing Forces in Axial-Flow Compressors: Part II—Analysis

摘要: An experimental and theoretical investigation was conducted to evaluate the effects seen in axial-flow compressors when centerline of rotor becomes displaced from static structure engine, thus creating circumferentially nonuniform rotor-tip clearances. This displacement produces unsteady flow creates a system destabilizing forces, which contribute significantly whirl instability turbomachinery. These forces were first identified by Thomas (1958. Bull. AIM, 71, No. 11/12, pp. 1039-1063.) for turbines Alford (1965. J. Eng. Power, Oct., 333-334) jet engines. In Part I, results an these phenomena presented. this II, three analytic models used predict both magnitude direction Thomas/Alford force its normalized form, known as β coefficient, tested I. addition, whirling shaft simulated differences between with offset actual eccentric rotor. The also assess influence nonaxisymmetric pressure distribution on spool, not measured experiment. evaluated (I) two-sector parallel compressor (2SPC) model, (2) infinite-segment-parallel-compressor (ISPC) (3) two-coupled actuator disk (2CAD) model. analyses found be agreement data sign trend. Thus, validated provide general means aerodynamic axial turbine tools have potential improve design rotordynamically stable