A Visual Study of Turbine Blade Pressure-Side Boundary Layers

Han, L. S.; Cox, W. R.

doi:10.1115/82-gt-47

Cited by 14 publications

(18 citation statements)

References 11 publications

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“…These data thus show that the primary vortex shedding frequency is generally more easily identified in PSD profiles obtained within the pressure side wake. This is consistent with results from Han and Cox [11] and Sieverding et al [14], who indicate that the pressure side vortex plays a more dominant role and is stronger than the suction side vortex. Some investigators believe that this is due to thinner pressure side boundary layers which often separate at or near the trailing edge.…”

Section: Power Spectral Density (Psd) Profilessupporting

confidence: 92%

“…Distributions of mean velocity, turbulence intensity, and Reynolds stress components illustrate the complex nature of the near wake. Han and Cox [11] detect von Kármán vortices near the trailing edge region of a turbine airfoil, and conclude that von Kármán vortex spacing in the near-wake region increases with distance from the trailing edge, partly because of reduced velocity deficits. Sieverding and Heinemann [12] examine vortex shedding and development both from flat plates and turbine cascades in an effort to correlate Strouhal numbers with Mach number and Reynolds number, and to relate vortex shedding frequencies to the boundary layer character on the blade surfaces.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Wake Turbulence Structure Downstream of a Cambered Airfoil in Transonic Flow: Effects of Surface Roughness and Freestream Turbulence Intensity

Zhang

Ligrani

2006

International Journal of Rotating Machinery

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The wake turbulence structure of a cambered airfoil is studied experimentally, including the effects of surface roughness, at different freestream turbulence levels in a transonic flow. As the level of surface roughness increases, all wake profile quantities broaden significantly and nondimensional vortex shedding frequencies decrease. Freestream turbulence has little effect on the wake velocity profiles, turbulence structure, and vortex shedding frequency, especially downstream of airfoils with rough surfaces. Compared with data from a symmetric airfoil, wake profiles produced by the cambered airfoils also have significant dependence on surface roughness, but are less sensitive to variations of freestream turbulence intensity. The cambered airfoil also produces larger streamwise velocity deficits, and broader wakes compared to the symmetric airfoil.

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Section: Power Spectral Density (Psd) Profilessupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Wake Turbulence Structure Downstream of a Cambered Airfoil in Transonic Flow: Effects of Surface Roughness and Freestream Turbulence Intensity

Zhang

Ligrani

2006

International Journal of Rotating Machinery

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“…This reflects the difference in thickness between the boundary layers at separation. A similar difference in the vortex rows was reported by Han and Cox (1983) behind a turbine cascade.…”

Section: Vortex Sheddingsupporting

confidence: 82%

Loss Production in the Wake of a Simulated Subsonic Turbine Blade

Roberts

Denton

1996

Volume 1: Turbomachinery

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The time-averaged flow in the wake of a model of a turbine blade was surveyed using a three-hole pressure probe; boundary layer traverses were also carried out using a flattened pilot probe. Loss coefficients were derived from the mass-weighted deficit in stagnation pressure. Results showing the progression of loss with streamwise distance along the surface and the wake of the model are presented. It was found that the loss generated in the wake comprised one-third of the profile loss when a well-developed vortex street was present in the wake. This proportion was reduced by increasing the thickness of the suction surface boundary layer, and by simulating the deviation that occurs in a real turbine blade. In both cases the strength of the vortex street was also shown to have been reduced.

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“…In the area near the trailing edge, there is a strong shear flow owing to the difference between the boundary layer velocity of the suction side and the pressure side (Nishiyarna, 1992). From this, it can be assumed that Kerman vortices fonn after the trailing edge (Han and Cox, 1982), but this remark must be confirmed by flow visualization. Furthermore, the curved shape difference between the distributions of the two Reynolds numbers (40,000 and 160,000) suggest that the length of the separation bubble is closely related to the flow angle.…”

Section: Re=40 000mentioning

confidence: 95%

Characteristics of a Turbine Cascade at Low Reynolds Numbers

Murata

Abe²,

Tsutsui³

1997

Volume 1: Aircraft Engine; Marine; Turbomachinery; Microturbines and Small Turbomachinery

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The aerodynamic characteristics of turbine cascades are thought to be relatively satisfactory due to the favorable pressure of the accelerating flow. But within the low Reynolds number region of 50,000 where the 300kW ceramic gas turbines which are being developed under the New-Sunshine Project of Japan operate, the characteristics such as boundary layer separation and reattachment which lead to prominent power losses cannot be easily predicted. In this research, experiments have been conducted to evaluate the performance of a linear two dimensional turbine cascade. Surface pressure distributions of the airfoil were measured for a range of blade chord Reynolds numbers from 40,000 to 160,000 (at inlet), and at 1.3% inlet turbulence intensity. In addition, the wake of the cascade was measured simultaneously using a five hole pilot tube. Traverses of the wake show that there is a drastic increase in the mean total pressure loss at the wake between the Reynolds number of 80,000 to 40,000, and in some conditions, a rise as much as 10% was confirmed. Thus, in accordance with the pressure distribution of the surface of the airfoil, a relation between the total pressure loss and the length of the laminar separation bubble formed on the airfoil could be seen.

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A Visual Study of Turbine Blade Pressure-Side Boundary Layers

Cited by 14 publications

References 11 publications

Wake Turbulence Structure Downstream of a Cambered Airfoil in Transonic Flow: Effects of Surface Roughness and Freestream Turbulence Intensity

Wake Turbulence Structure Downstream of a Cambered Airfoil in Transonic Flow: Effects of Surface Roughness and Freestream Turbulence Intensity

Loss Production in the Wake of a Simulated Subsonic Turbine Blade

Characteristics of a Turbine Cascade at Low Reynolds Numbers

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