Secondary Flow in Variable Stator Vanes With Penny-Cavities

Stummann, Simon; Pohl, Daniel; Jeschke, Peter; Wolf, Hannes; Halcoussis, Alexander; Franke, Matthias

doi:10.1115/gt2017-63771

Cited by 6 publications

(11 citation statements)

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“…The pressure distribution around the airfoil controls the pressure distribution on the hub and the pressure distribution on the hub controls the penny cavity leakage flow, as has been shown by Stummann [14]. With increasing penny annular gap size, the pressure at the suction peak at about 10% -15% of the chord length increases.…”

Section: (3a)mentioning

confidence: 78%

“…The losses caused by the penny leakage and the hub-side half-gap vortex are superimposed. The additional penny loss results from the formation of a penny vortex and the resulting mixing losses, as described by Stummann [14]. The location of maximum penny loss is slightly above the half-gap vortex and more distant from the suction side of the vane.…”

Section: Total Pressure Lossmentioning

confidence: 91%

“…Figure 11 shows the difference between double penny and no-penny cavity in non-dimensional streamwise vorticity at the outlet plane for the experiment and the RANS simulation. Stummann's numerical studies [14,16] show that the suction-side outflow of the penny cavity forms an asymmetric, counter-rotating vortex pair: A suction-sided penny-vortex (SSPV) rotating clockwise and a pressure-sided penny-vortex (PSPV) rotating counter-clockwise in flow direction. The low-energy SSPV already disappears in the blade passage due to the pressure gradient and can therefore not be observed in the outlet plane.…”

Section: (3a)mentioning

confidence: 99%

“…A shroud leakage, which was investigated by Mattingly [3], is not taken into account. Results of the CFD studies about the penny leakage have already been published [13][14][15][16] as part of this research project. This paper is the first publication in which experimental data on penny leakage is reported.…”

Section: Introductionmentioning

confidence: 99%

“…Following on from this, Stummann [14] presented simulations of the hub penny leakage with turbulence resolving Detached-Eddy Simulations (DES) and compared them to RANS simulations. Stummann described in detail how the penny leakage from the suction side outflow region forms an asymmetrical counter-rotating vortex pair.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Variable Stator Vane Penny Gap Aerodynamic Measurements and Numerical Analysis in an Annular Cascade Wind Tunnel

Pohl

Janssen

Jeschke

et al. 2020

JGPP

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This paper presents detailed measurements and post-test simulations of the penny cavity leakage flow and its interaction with the mainstream flow in an annular cascade wind tunnel. The annular cascade wind tunnel consists of a single row of 30 variable stator vanes, derived from a high-pressure compressor stator with inner and outer vane disks, called pennies, whichwhen assembled in the hub and casing wallsleave cylindrical-shaped ring gaps called penny cavities. The wind tunnel runs at a Mach number of 0.34 at the stator inlet and a Reynolds number of 3.82 x 10 5 based on axial chord length at 50% span. Two different penny gap sizes on the hub are compared to a reference case without a penny gap. Detailed 2D-traverses were performed with multi-hole pressure and hot-wire-probes covering 2.5 passages in the inflow and outflow of the stator row. Pressure taps were embedded in the airfoil surface and inside the penny cavity. Surface oil flow measurements were conducted with different colors for the vane suction side, pressure side, hub and the penny cavity to detect the secondary flow phenomena. Reynoldsaveraged Navier-Stokes (RANS) simulations, using the measured boundary conditions, were compared to experimental data. As a result, a relative increase in the total pressure loss coefficient of 1.9% for the nominal and 6.8% for the double penny gap was measured compared to no-penny cavity. The additional penny losses are limited to the lower 40% span. The post-test simulations are in good agreement with the measurements, showing that the outflow from the penny cavity on the suction side generates vortices, which cause additional losses. The penny vortices are detected in the outlet plane by an increase in turbulence intensity and streamwise vorticity. However, the additional penny losses are overestimated in the simulation by up to 7.3%. A change in the pressure fields with an increasing penny gap size, both around the airfoil and inside the penny cavity, can be seen in the numerical and experimental results. The outflow regions of the penny cavity, estimated by simulations, are confirmed by the results of the surface oil flow measurements. In summary, this paper consolidates previous numerical analyses carried out by the authors [13-16] on penny cavity leakage flow effects with experimental data for different penny gap sizes.

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Section: (3a)mentioning

confidence: 78%

Section: Total Pressure Lossmentioning

confidence: 91%

Section: (3a)mentioning

confidence: 99%