An experimental study of separation control on ultra-highly-loaded low pressure turbine blade by surface roughness

2015 ◽  
Vol 24 (3) ◽  
pp. 229-238 ◽  
Author(s):  
Shuang Sun ◽  
Zhijun Lei ◽  
Xingen Lu ◽  
Shengfeng Zhao ◽  
Junqiang Zhu
Keyword(s):  
Experimental Study ◽  
Surface Roughness ◽  
Turbine Blade ◽  
Low Pressure ◽  
Separation Control ◽  
Low Pressure Turbine ◽  
Highly Loaded

A Low Reynolds Number Experimental Evaluation of Tubercles on a Low-Pressure Turbine Cascade

2019 ◽  
Author(s):  
Stephen A. Pym ◽  
Asad Asghar ◽  
William D. E. Allan ◽  
John P. Clark
Keyword(s):  
Boundary Layer ◽  
Turbine Blade ◽  
Reynolds Numbers ◽  
Low Pressure ◽  
Blade Profile ◽  
Suction Surface ◽  
Low Reynolds Numbers ◽  
Low Pressure Turbine ◽  
Low Reynolds ◽  
Highly Loaded

Abstract Aircraft are operating at increasingly high-altitudes, where decreased air density and engine power settings have led to increasingly low Reynolds numbers in the low-pressure turbine portion of modern-day aeroengines. These operating conditions, in parallel with highly-loaded blade profiles, result in non-reattaching laminar boundary layer separation along the blade suction surface, increasing loss and decreasing engine performance. This work presents an experimental investigation into the potential for integrated leading-edge tubercles to improve blade performance in this operating regime. A turn-table cascade test-section was constructed and commissioned to test a purpose-designed, forward-loaded, low-pressure turbine blade profile at various incidences and Reynolds numbers. Baseline and tubercled blades were tested at axial chord Reynolds numbers at and between 15 000 and 60 000, and angles of incidence ranging from −5° to +10°. Experimental data collection included blade surface pressure measurements, total pressure loss in the blade wakes, hot-wire anemometry, surface hot-film measurements, and surface flow visualization using tufts. Test results showed that the implementation of tubercles did not lead to a performance enhancement. However, useful conclusions were drawn regarding the ability of tubercles to generate stream-wise vortices at ultra-low Reynolds numbers. Additional observations helped to characterize the suction surface boundary layer over the highly-loaded, low-pressure turbine blade profile when at off-design conditions. Recommendations were made for future work.

Numerical Simulation of Low-Pressure Turbine Blade Separation Control

AIAA Journal ◽  
2010 ◽  
Vol 48 (8) ◽  
pp. 1582-1601 ◽  
Author(s):  
A. Gross ◽  
H. F. Fasel
Keyword(s):  
Numerical Simulation ◽  
Turbine Blade ◽  
Low Pressure ◽  
Separation Control ◽  
Low Pressure Turbine

Separation Control on a Low-Pressure Turbine Blade using Microjets

2013 ◽  
Vol 29 (4) ◽  
pp. 867-881 ◽  
Author(s):  
Erik Fernandez ◽  
Rajan Kumar ◽  
Farrukh Alvi
Keyword(s):  
Turbine Blade ◽  
Low Pressure ◽  
Separation Control ◽  
Low Pressure Turbine

Numerical and Experimental Investigation of Aerodynamics on Flow Around a Highly Loaded Low-Pressure Turbine Blade With Flow Separation Under Steady and Periodic Unsteady Inlet Flow Condition

2016 ◽  
Author(s):  
Ali Nikparto ◽  
Meinhard T. Schobeiri
Keyword(s):  
Boundary Layer ◽  
Turbine Blade ◽  
Flow Condition ◽  
Turbulence Models ◽  
Low Pressure ◽  
Rotor Blades ◽  
Navier Stokes ◽  
Inlet Flow ◽  
Low Pressure Turbine ◽  
Highly Loaded

Understanding the behavior of flow field around a turbine blade is of importance in gas turbine engineering and it can affect the design and performance of engine elements. An important phenomena that can affect the flow regime is the effect that impinging wakes, originating from stator blades, have on the flow around rotor blades. Reynolds Averaged Navier-Stokes (RANS) equation, in conjunction with turbulence models enables us to model flow fields. This study numerically and experimentally investigates the behavior of the boundary layer development along the suction and pressure surfaces of a highly loaded low-pressure turbine blade under steady and unsteady inlet flow condition. For unsteady case a range of reduced frequencies of the incoming wakes were modeled and studied. Also it includes a comprehensive assessment of predictive capability of RANS numerical tools. To evaluate the reliability of current RANS-based numerical method, a rigorous boundary layer and heat transfer measurement were done in unsteady boundary layer cascade facility of Turbomachinery Performance and Flow Research Lab (TPFL) of Texas A&M University. Aerodynamics experiments include measuring the onset of the boundary layer, its transition, separation and re-attachment using miniature hot wire probes. All measurements were performed for different wake frequencies and flow conditions and results were compared to the obtained simulation results. Comparisons of the experimental and numerical results detail the differences in predictive capabilities of the RANS methods in terms of the locating the onset and length of separation, velocity profile inside boundary layer, velocity fluctuations.

Numerical Investigations of Flow Separation Control for a Low Pressure Turbine Blade Using Steady and Pulsed Vortex Generator Jets

2010 ◽  
Author(s):  
Xiaomin Liu ◽  
Haiyang Zhou
Keyword(s):  
Turbine Blade ◽  
Flow Separation ◽  
Vortex Generator ◽  
Suction Side ◽  
Low Pressure ◽  
Pulse Frequency ◽  
Separation Control ◽  
Flow Separation Control ◽  
Low Pressure Turbine ◽  
Vortex Generator Jets

This paper investigated numerically the application of Vortex Generator Jets (VGJs) to control flow separation on the suction side of a low pressure turbine blade. Firstly, numerical simulations of flow separation for a LPT blade, which based on Menter’s SST k-ω turbulence model coupled with Langtry-Menter transition model, were performed for different Reynolds numbers Re∼100,000, 75,000, 50,000 and 25,000, for three freestream turbulence intensity (FSTI) of 0.08%, 2.35% and 6.0%. The pressure distributions around the turbine blade and streamline plots showing the flow separation were presented in this paper. Good agreement of the numerical and experimental results also showed the validity of the numerical scheme for simulating the flow separation occurring on a low pressure turbine blade. And then, steady Vortex Generator Jets (steady VGJs) having pitch angle of 30°, skew angle of 90°, blowing ratio of 2.0 were used to control the flow separation in the suction side of the low pressure turbine blade. Although steady VGJs have been illustrated to be extremely robust at suppressing low Reynolds number separation, the practical application of VGJs in the low pressure turbine engine is in the pulsed mode. The injection mass flow requirements of pulsed Vortex Generator Jets (pulsed VGJs) can be reduced drastically when similar flow control effect is obtained using steady VGJs. For pulsed VGJs, the pulse frequency has been found to be an important control parameter for the flow separation control. In this paper, cases with the duty cycle of 0.5 were studied for the pulse frequency ranging from 2.5Hz to 10Hz at Re = 25,000 and freestream turbulence level of 0.08%. The numerical results showed that pulsed VGJs can effectively reduce and even eliminate the flow separation on the blade suction surface while there is an optimal pulse frequency. The flow control mechanism of VGJs on LPT blade was also revealed.

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