Low Reynolds number loss reduction on turbine blades with dimples and V-grooves

Lake, James; King, Paul I.; Rivir, Richard B.

doi:10.2514/6.2000-738

Cited by 67 publications

(39 citation statements)

References 5 publications

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“…However, at lower Reynolds number conditions which correspond to high altitudes and cruise speeds the boundary layers on the airfoil surface have a tendency to remain laminar; hence, the flow may separate on the suction surface of the turbine blades before it becomes turbulent. This laminar separation causes unpredicted losses, substantial drops in efficiency, and increase in fuel consumption [1][2][3].…”

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confidence: 99%

A Computational Fluid Dynamics Study of Transitional Flows in Low-Pressure Turbines Under a Wide Range of Operating Conditions

Suzen

Huang

Ashpis

et al. 2006

Journal of Turbomachinery

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A transport equation for the intermittency factor is employed to predict the transitional flows in low-pressure turbines. The intermittent behavior of the transitional flows is taken into account and incorporated into computations by modifying the eddy viscosity, ^t, with the intermittency factor, y. Turbulent quantities are predicted by using Menter's twoequation turbulence model (SST). The intermittency factor is obtained from a transport equation model which can produce both the experimentally observed streamwise variation of intermittency and a realistic profile in the cross

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confidence: 99%

A Computational Fluid Dynamics Study of Transitional Flows in Low-Pressure Turbines Under a Wide Range of Operating Conditions

Suzen

Huang

Ashpis

et al. 2006

Journal of Turbomachinery

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“…For low pressure turbines the flow is mostly turbulent at the high Reynolds number conditions encountered at take off and the efficiency is at its design maximum. However, due to decrease of Reynolds number caused by high altitudes conditions at cruise speeds, design based on the sea level conditions tends to underpredict-losses and thus leads to substantial drops in efficiency (Mayle 1991;Rivir 1996;Lake et al 2000). These losses are attributed to flow separation on the suction surface of the turbine blades.…”

mentioning

confidence: 99%

Predictions of separated and transitional boundary layers under low-pressure turbine airfoil conditions using an intermittency transport equation

Suzen

Huang

Hultgren

et al. 2001

39th Aerospace Sciences Meeting and Exhibit

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A new transport equation for the intermittency factor was proposed to predict separated and transitional boundary layers under low-pressure turbine airfoil conditions. The intermittent behavior of the transitional flows is taken into account and incorporated into computations by modifying the eddy viscosity, µt , with the intermittency factor, y. Turbulent quantities are predicted by using Menter's two-equation turbulence model (SST). The intermittency factor is obtained from a transport equation model, which not only can reproduce the experimentally observed streamwise variation of the intermittency in the transition zone, but also can provide a realistic cross-stream variation of the intermittency profile.In this paper, the intermittency model is used to predict a recent separated and transitional boundary layer experiment under low pressure turbine airfoil conditions. The experiment provides detailed measurements of velocity, turbulent kinetic energy and intermittency profiles for a number of Reynolds numbers and freestream turbulent intensity conditions and is suitable for validation purposes. Detailed comparisons of computational 'Postdoctoral Researcher, Member AIAA. t Associate Professor, Senior Member AIAA.Associate Fellow AIAA § Aerospace Engineer, Senior Member AIAA.

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Section: Introductionmentioning

confidence: 99%

“…7 However, currently existing data for turbomachinery blades only go as low as Reynolds numbers in the 40,000 range. 8,9 Thus, there is a strong need to obtain data for turbomachinery blades at the low Reynolds number range.Modern gas turbines oftentimes employ a multi-stage axial compressor where the pressure rise across each compressor stage is relatively small. Since compressor blades operate in an adverse pressure gradient environment, it is relatively easy to cause flow separation (i.e., stall).…”

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confidence: 99%

Flow Visualization Study on the Effect of a Gurney Flap in a Low Reynolds Number Compressor Cascade

Myose

Lietsche

Scholz

et al. 2006

6th AIAA Aviation Technology, Integration and Operations Conference (ATIO)

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IntroductionThe first century of heavier-than-air powered flight has been dominated by the desire to fly "faster, higher, and farther." Fulfilling this desire led to the development of the gas turbine driven turbojet. Since their introduction more than six decades ago, gas turbine driven engines have become quite powerful in terms of thrust produced 1 while achieving significant improvements in fuel efficiency 2 and reductions in maintenance costs 3 . Today, gas turbine driven turbofans and turboprops dominate the field of aero-propulsion for aircraft varying from "moderate" size general aviation planes to large passenger jets. This domination of gas turbine engines is true even in some "smaller" aircraft like Unmanned Aerial Vehicles (UAV) including the Air Force RQ-4A Global Hawk and HQ-9A Predator B. Since gas turbine engines are so prevalent in aviation, it is important to learn what affects their performance. Gas turbine 2 American Institute of Aeronautics and Astronautics driven engines are designed for, and can typically be operated at, optimum performance in medium to large size aircraft applications because their flight envelopes are so well defined. However, recent advances in UAV applications have pushed the flight envelope into the lesser known low Reynolds number flight regime.A typical general aviation aircraft may involve wing chord Reynolds number on the order of 10 6 to 10 7 while large passenger aircraft might be in the 10 8 range. 4 Recently, however, there has been a strong interest in very small reconnaissance vehicles called Micro Air Vehicles (MAV) which typically have a wing chord length on the order of 6 inches (0.15 m). MAV's involve chord Reynolds number on the order of 20,000 to 200,000, and very little aerodynamic data exists in this range.5 Similar issues exist in the gas turbine engine research area as well. A microscale engine (i.e., micro-fabricated gas turbine) for application on MAV involves design blade chord Reynolds numbers of about 20,000 or less.6 In addition to small-scale effects, extreme operating conditions on conventional gas turbine engines often result in low Reynolds numbers. The low-pressure turbine blades on UAV engines, which are in operation today, involve blade chord Reynolds numbers less than 25,000 under high-altitude operating conditions. 7 However, currently existing data for turbomachinery blades only go as low as Reynolds numbers in the 40,000 range. 8,9 Thus, there is a strong need to obtain data for turbomachinery blades at the low Reynolds number range.Modern gas turbines oftentimes employ a multi-stage axial compressor where the pressure rise across each compressor stage is relatively small. Since compressor blades operate in an adverse pressure gradient environment, it is relatively easy to cause flow separation (i.e., stall). The consequences of compressor blade stall can simply be poor performance or, in the worst case scenario, significant engine damage.3 In order to prevent compressor blade stall, gas turbine engines are normally operated close ...

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Low Reynolds number loss reduction on turbine blades with dimples and V-grooves

Cited by 67 publications

References 5 publications

A Computational Fluid Dynamics Study of Transitional Flows in Low-Pressure Turbines Under a Wide Range of Operating Conditions

A Computational Fluid Dynamics Study of Transitional Flows in Low-Pressure Turbines Under a Wide Range of Operating Conditions

Predictions of separated and transitional boundary layers under low-pressure turbine airfoil conditions using an intermittency transport equation

Flow Visualization Study on the Effect of a Gurney Flap in a Low Reynolds Number Compressor Cascade

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