Influence of Free Stream Turbulence and Blade Pressure Gradient on Boundary Layer and Loss Behaviour of Turbine Cascades

Hoheisel, H.; Kiock, R.; Lichtfuss, H. J.; Fottner, Leonhard

doi:10.1115/86-gt-234

Cited by 26 publications

(7 citation statements)

References 2 publications

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“…No clear correlation was found, either by correlating against centre of pressure, or against the location of the point of peak velocity. Previous investigations, Hashimoto and Kimura (1984), and Hoheisel et al (1986), have concluded that aft-loading is preferable, although at similar conditions to the 'flap tests' (low inlet turbulence, low Mach Number) there was not much difference. For our additional 'flap tests' (described later), where inlet wakes were present, aft-loading did appear to give less loss.…”

Section: Diffusion Factors and Loading Distributionmentioning

confidence: 80%

Development of Blade Profiles for Low Pressure Turbine Applications

Curtis

Hodson

Banieghbal

et al. 1996

Volume 1: Turbomachinery

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This paper describes a programme of work, largely experimental, which was undertaken with the objective of developing an improved blade profile for the low-pressure turbine in aero-engine applications. Preliminary experiments were conducted using a novel technique. An existing cascade of datum blades was modified to enable the pressure distribution on the suction surface of one of the blades to be altered. Various means, such as shaped inserts, an adjustable flap at the trailing edge, and changing stagger were employed to change the geometry of the passage. These experiments provided boundary layer and lift data for a wide range of suction surface pressure distributions. The data was then used as a guide for the development of new blade profiles. The new blade profiles were then investigated in a low-speed cascade that included a set of moving bars upstream of the cascade of blades 10 simulate the effect of the incoming wakes from the previous blade row in a multistage turbine environment. Results are presented for two improved profiles that are compared with a datum representative of current practice. The experimental results include loss measurements by wake traverse, surface pressure distributions, and boundary layer measurements. The cascades were operated over a Reynolds Number range from 0.7 × 105 to 4.0 × 105. The first profile is a “laminar flow” design that was intended to improve the efficiency at the same loading as the datum. The other is a more highly loaded blade profile intended to permit a reduction in blade numbers. The more highly loaded profile is the most promising candidate for inclusion in future designs. It enables blade numbers to be reduced by 20%, without incurring any efficiency penalty. The results also indicate that unsteady effects must be taken into consideration when selecting a blade profile for the low-pressure turbine.

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Section: Diffusion Factors and Loading Distributionmentioning

confidence: 80%

Development of Blade Profiles for Low Pressure Turbine Applications

Curtis

Hodson

Banieghbal

et al. 1996

Volume 1: Turbomachinery

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“…If the injection of coolant had caused an earlier laminar to turbulent boundary layer transition, and in so doing prevented the formation of a separation bubble, this could reduce the overall loss. Indeed, Hoheisel et. al.…”

Section: Results -Individual Rowsmentioning

confidence: 99%

Efficiency Measurements of an Annular Nozzle Guide Vane Cascade With Different Film Cooling Geometries

Day

Oldfield

Lock

et al. 1998

Volume 4: Heat Transfer; Electric Power; Industrial and Cogeneration

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This paper further extends the research reported by Day et al. (1997), which reported aerodynamic efficiency measurements on an annular cascade of engine representative transonic nozzle guide vanes with extensive film cooling. This work compares the measured aerodynamic efficiencies of blades with 14 rows of cylindrical cooling holes with a new geometry in which 8 of the rows have been replaced by holes having a fan-shaped exit geometry. The effects of adding trailing edge slot ejection are also presented. By selectively blocking rows of holes, the cumulative effect on the mid-span efficiency of adding rows of cooling holes has also been determined. A dense foreign gas (SF6/Ar mixture) is used to simulate engine representative coolant-to-mainstream density ratios, momentum ratios and blowing rates under ambient temperature conditions. The flowfield measurements have been obtained using a four-hole pyramid probe in a short duration blowdown facility which correctly models engine Reynolds and Mach numbers, as well as the inlet turbulence intensity. Experimental results are presented as area traverse maps (total pressure, isentropic Mach number and flow angles), from which the incremental changes in efficiency due to film cooling have been calculated. The effects of different assumptions for the coolant total pressure are shown. Experimental data agrees reasonably well with loss predictions using a Hartsel model.

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“…Significant headway has been made during the past decade towards the reduction of LPT airfoil counts through high-lift airfoil designs. Initial research on the aerodynamics of more highly loaded LPTs appears to have been based on the family of T104-T106 airfoils developed by Hoheisel et al [3]. This family includes airfoils with both front and aft loading having values of the non-dimensional Zweifel coefficient, Zw, of about 1.04 to 1.07.…”

Section: Introductionmentioning

confidence: 99%

Toward the Expansion of Low-Pressure-Turbine Airfoil Design Space

Praisner

Grover

Knezevici

et al. 2013

Journal of Turbomachinery

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Influence of Free Stream Turbulence and Blade Pressure Gradient on Boundary Layer and Loss Behaviour of Turbine Cascades

Cited by 26 publications

References 2 publications

Development of Blade Profiles for Low Pressure Turbine Applications

Development of Blade Profiles for Low Pressure Turbine Applications

Efficiency Measurements of an Annular Nozzle Guide Vane Cascade With Different Film Cooling Geometries

Toward the Expansion of Low-Pressure-Turbine Airfoil Design Space

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