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Characterizing the Separation and Reattachment of Suction Surface Boundary Layer in Low Pressure Turbine Using Massively Parallel Large Eddy SimulationsJagannathan, Shriram 2010 December 1900 (has links)
The separation and reattachment of the suction surface boundary layer in a low pressure turbine is characterized using large-eddy simulation at Re=68,000 based on freestream velocity and suction surface length. A high pass filtered Smagorinsky model is used for modeling the sub-grid scales. The onset of time mean separation is at s=so = 0:61 and reattachment at s=so = 0:81, extending over 20% of the suction surface. The boundary layer is convectively unstable with a maximum reverse flow velocity of about 13% of freestream. The breakdown to turbulence occurs over a very short distance of suction surface which is followed by reattachment. Detailed investigations into the structure and kinematics of the bubble and turbulence statistics are presented. The vortex shed from the bubble, convects downstream and interacts with the trailing edge vortices increasing the turbulence intensity. On the suction side, dominant hairpin structures near the transitional and turbulent flow regime are observed. These hairpin vortices are carried by the freestream even downstream of the trailing edge of the blade with a possibility of reaching the next stage. Longitudinal streaks that evolve from the breakdown of hairpin vortices formed near the leading edge are observed on the pressure surface.
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Experimental Investigation Of The Effects Of Waveform Tip Injection On The Characteristics Of Tip Leakage Vortex In A Lpt CascadeMercan, Bayram 01 February 2012 (has links) (PDF)
This study presents the results of an experimental study that investigates the effects of uniform/waveform tip injection along the camberline on the total pressure loss characteristics downstream of a row of Low Pressure Turbine (LPT) blades. The experiments are performed in a low speed cascade facility. This injection technique involves spanwise jets at the tip that are issued from a series of holes along the camber line normal to the freestream flow direction. The injection mass flow rate from each hole is individually controlled using computer driven solenoid valves and therefore the flow injection geometrical pattern at the tip can be adjusted to any desired waveform shape, and can be uniform as well as waveform along the camber. Measurements involve Kiel probe traverses for different injection scenarios 0.5 axial chords downstream of the blades. Results show that, instead of performing uniform mass injection along the camberline, by selecting an appropriate waveform injection pattern one can reduce the total loss levels of the blade, including the tip leakage loss as well as the wake losses.
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Experimental Investigation Of Boundary Layer Separation Control Using Steady Vortex Generator Jets On Low Pressure TurbinesDogan, Eda 01 June 2012 (has links) (PDF)
This thesis presents the results of an experimental study that investigates the effects of steady vortex generator jets (VGJs) integrated to a low pressure turbine blade to control the laminar separation bubble occurring on the suction surface of the blade at low Reynolds numbers. The injection technique involves jets issued from the holes located near the suction peak of the test blade which is in the middle of a five-blade low speed linear cascade facility. Three injection cases are tested with different blowing ratio values ranging from low to high. Surface pressure and particle image velocimetry (PIV) measurements are performed. The results show that steady VGJ is effective in eliminating the laminar separation bubble. Also it is observed that to have fully developed attached boundary layer, blowing ratio should be chosen accordingly since a very thin separation zone still exists at low blowing ratios.
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FLOW SEPARATION CONTROL FOR CYLINDER FLOW AND CASCADE FLOW USING GENERATOR JETSKASLIWAL, AMIT 03 April 2006 (has links)
No description available.
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Characterization of Internal Wake Generator at Low Reynolds Number with a Linear Cascade of Low Pressure Turbine BladesNessler, Chase A. 12 April 2010 (has links)
No description available.
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Low Pressure Turbine Flow Control with Vortex Generator JetsWilliams, Charles P. 11 October 2016 (has links)
No description available.
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Separation Flow Control with Vortex Generator Jets Employed in an Aft-Loaded Low-Pressure Turbine Cascade with Simulated Upstream WakesGompertz, Kyle Adler 08 September 2009 (has links)
No description available.
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Design Optimization of a Non-Axisymmetric Endwall Contour for a High-Lift Low Pressure Turbine BladeDickel, Jacob Allen 30 August 2018 (has links)
No description available.
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Impact of Free-Stream Turbulence Intensity on the Endwall Region of Low Pressure Turbine BladesDonovan, Molly Hope 15 May 2023 (has links)
No description available.
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Capitalizing on Convective Instabilities in a Streamwise Vortex-Wall InteractionBenton, Stuart Ira 15 October 2015 (has links)
No description available.
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