Wake Induced Time-Variant Aerodynamics Including Rotor-Stator Axial Spacing Effects

Abstract

The overall objective of this experimental program was to quantify the effects of rotor-stator axial spacing on the fundamental time-variant aerodynamics relevant to forced response in turbomachinery. This was accomplished in a large-scale, low-speed, single-stage research compressor which permitted two rotor-stator axial spacing ratios representative of those found in advanced design compressors to be investigated. At each value of the axial spacing ratio, the aerodynamically induced fluctuating surface pressure distributions on the downstream vane row, with the primary source of excitation being the upstream rotor wakes, were measured over a wide range of compressor operating conditions. The velocity fluctuations created by the passage of the rotor blades were measured in the nonrotating coordinate system. Data obtained described the variation of the rotor wake with both loading and axial distance from the rotor as parameters. These data also served as a reference in the analysis of the resulting time-variant pressure signals on the vane surfaces.

Navier-Stokes and Potential Calculations of Axial Spacing Effect on Vortical and Potential Disturbances and Gust Response in an Axial Compressor

“…Many researchers have undertaken the study of gust and gust response in axial compressors, e.g., Whitehead (1970), Goldstein and Atassi (1976), Fleeter et al (1978Fleeter et al ( , 1980, Gallus et al (1980), Capece et al (1986 and1987), Lewis et al (1987), Rai (1987), Rai et al (1990), Giles (1988), Hall and Crawley (1987), Hall and Verdon (1989), Hardin et al (1987), Manwaring and Fleeter (1989, 1990, 1991, Scott and Atassi (1990), Verdon and Hall (1990), Fang (1991), Korakianitis (1991), Henderson and Fleeter (1993), and others. Kielb and Chiang (1992) provided a summary of recent advances in forced response analyses.…”

“…Aeromechanically, the present understanding of axial gap effect also needs clarification. Among others, Fleeter et al (1981) carried out an important experimental study on the effect of axial spacing on gust response for a rotor/stator configuration and reported that the unsteady blade surface pressure increases significantly with decreased spacing at 100% speed but not at 70% speed. They also observed wave related phenomenon from unsteady pressure data.…”

“…They also observed wave related phenomenon from unsteady pressure data. Gallus et al (1982) undertook extensive investigation of the blade number ratio and blade row spacing on stator dynamic loading and stage sound pressure level. They found that both vortical and potential effects are important in determining the blade response for very small gap.…”

Forcing Function Effects on Unsteady Aerodynamic Gust Response: Part 2 — Low Solidity Airfoil Row Response

“…A number of experiments have been directed at the verification of unsteady aerodynamic models appropriate for blade row forced response prediction and the determination of their applicability and limitations for example [Frank and Henderson [1980]. Fleeter, Jay, and Bennett [1978, 1981 Gallus, Lambertz, and Wallman [1980] Dring et al [1982] Hodson [1985 Capece, Manwaring, and Fleeter [1986], Fleeter [1987, 1989]. In these, the unsteady airfoil row response comparisons with linear theory were made without considering the fundamental gust modeling assumptions.…”

Experimental and Numerical Study of Gust and Gust Response in a Rotor/Stator Axial Compressor

“…The work of Valkov and Tan provided exceptional physical insight into the cause of unsteady blade loading due to moving wakes. Experimental studies which focus on the unsteady blade loading include Fleeter et al (1981), Capece and Fleeter (1987), Gallus et al (1982), Manwaring and Wisler (1993), and others. The work of Manwaring and Wisler emphasized the importance of properly accounting both vortical and potential contributions to calculate the total unsteady response.…”