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Showing 1 to 20 of 40 for “"freestream turbulence"”.
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The effects of freestream turbulence on the drag of a sphere
The effects of freestream turbulence intensity and integral length scale as freestream turbulent parameters on the drag coefficient of a solid sphere were experimentally investigated in a closed-circuit wind tunnel. The Reynolds number, Re = Ud/ν, was varied from 2.2×104 to 8×10 4 by using spheres …
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Effects of freestream turbulence on turbine blade heat transfer in transonic flow
The effects of grid generated freestream turbulence on surface heat transfer to turbine blades were measured experimentally. Time-resolved and unsteady heat flux measurements were made with Heat Flux Microsensors at two positions on the suction side of turbine blades. The experiments were conducted …
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The Effect of Freestream Turbulence on Separation at Low Reynolds Numbers in a Compressor Cascade
… to observe and quantify the effect of varying turbulence intensities on separation and performance in a compressor cascade at low Reynolds numbers. Tests were performed at 25° and 37.5° stagger angle, negative and positive angles of incidence up until the point of full stall, Reynolds numbers …
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The simultaneous measurement of time-resolved surface heat flux and freestream turbulence at a stagnation point
… documentation of the effects of local freestream turbulence on boundary layer heat transfer. The resulting time traces indicate a direct correlation between the turbulent velocity fluctuations and heat flux variation. The effects of apparent single-frequency turbulent components are …
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Showerhead Film Cooling Performance of a Turbine Vane at High Freestream Turbulence in a Transonic Cascade
… transfer coefficient due to local increase in freestream turbulence. Accurate numerical modeling of airfoil film cooling performance is a challenge as it is complicated by several factors such as film cooling hole shape, coolant-to-freestream blowing ratio, coolant-to-freestream momentum ratio, …
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The Physical Mechanism of Heat Transfer Augmentation in Stagnating Flows Subject to Freestream Turbulence and Related Studies
… mechanism of heat transfer augmentation due to freestream turbulence in classic Hiemenz stagnation flow was studied experimentally for the first time using time-resolved digital particle image velocimetry (TRDPIV) and a new thin film heat flux sensor called the Heat Flux Array (HFA). Unique …
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Performance of a Showerhead and Shaped Hole Film Cooled Vane at High Freestream Turbulence and Transonic Conditions
… Mach and Reynolds numbers and high inlet turbulence intensity and large length scale at the Virginia Tech Transonic Cascade facility. Three exit Mach/Reynolds number conditions were tested: 1.0/1,400,000; 0.85/1,150,000; and 0.60/850,000 where Reynolds number is based on exit conditions …
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"An Experimental Investigation of Showerhead Film Cooling Performance in a Transonic Vane Cascade at Low Freestream Turbulence"
… Tech's heated, blow-down wind tunnel. Two freestream exit Mach numbers of 0.76 and 1.0—corresponding to exit Reynolds numbers based on vane chord of 1.1x106 and 1.5x106, respectively—were tested at an inlet freestream turbulence intensity of two percent and an integral length scale …
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Effects of Freestream Turbulence, Turbulence Length Scale, and Reynolds Number on Turbine Blade Heat Transfer in a Transonic Cascade
… experimentally investigates the effect of high freestream turbulence intensity, turbulence length scale, and exit Reynolds number on the surface heat transfer distribution of a turbine blade at realistic engine Mach numbers. Passive turbulence grids were used to generate freestream turbulence …
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Fan-Shaped Hole Film Cooling on Turbine Blade and Vane in a Transonic Cascade with High Freestream Turbulence: Experimental and CFD Studies
… blade and vane. The study was operated with high freestream turbulence intensity (12% at the inlet) and large turbulence length scales (0.26 for blade, 0.28 for vane, normalized by the cascade pitch of 58.4mm and 83.3mm respectively). Both convective heat transfer coefficient, in terms of Nusselt …
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Measurements of pressure and thermal wakes in a transonic turbine cascade
The effects of freestream turbulence on the total pressure and total temperature in the wake of a cooled transonic turbine cascade with heated flow are presented in this thesis. The experiment was conducted in the Virginia Tech Cascade Wind Tunnel. A dual hot wire aspirating probe was used to make …
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On the Response of a Spherical Particle to Unsteady Flows at Finite Reynolds Numbers
The effect of turbulence on the motion of a freely settling particle is also investigated. In all cases considered, the inertial response time of the particle is the same as the Kolmogorov time scale of the freestream turbulence. Over the parameter range considered, turbulence is found to have a …
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Transition in boundary layer flows
… layer flows under the influence of various freestream conditions is described.<br/><br/>Velocity profiles are obtained automatically by means of a stepper-motor driven traverse mechanism which carries a hot wire probe connected to a constant temperature anemometer and associated …
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Effects of High Intensity, Large-Scale Freestream Combustor Turbulence On Heat Transfer in Transonic Turbine Blades
The influence of freestream turbulence representative of the flow downstream of a modern gas turbine combustor and first stage vane on turbine blade heat transfer has been measured and analytically modeled in a linear, transonic turbine cascade. Measurements were performed on a high turning, …
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Flow Visualization Study of Wake-Stabilized Diffusion Flames in a Crossflow: Effects of Crossflow Turbulence
Effects of crosswind turbulence on the mechanisms and flow structures affecting emissions from non-premixed wake stabilized flames from elevated stacks are investigated. In the current work, two conditions of upstream crossflow are tested to investigate the effects of turbulence on the flame, …
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Evaluation of a Heat Flux Microsensor in a Transonic Turbine Cascade
… the average heat transfer coefficient measured. Turbulence grids were used to study how offset affects the heat transfer coefficient with freestream turbulence added to the flow. The time constant of the directly deposited gage was measured to be 856 ms compared to less than 30 ms for the insert …
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Measurements and Predictions of Heat Transfer for a First Vane Design
… far from the contoured endwall. The effects of freestream turbulence with respect to the contour were examined. Results showed a significant increase in heat transfer at elevated freestream turbulence levels at each span location. The effects of the contour were minimal compared to the effects …
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Boundary layer transition in simulated turbine blade flow
… velocity distribution at various levels of freestream turbulence giving a range of normal and separation bubble type transitions. The concept of statistical similarity of transition regions was observed to remain intact for severe adverse pressure gradients, including cases where separation …
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High Fidelity Simulation of Loss Mechanisms in Compressors
… vortex and compressor cascade subjected to freestream turbulence. The results show that both resolving local entropy generation rate and capturing the inception and growth of instabilities are critical to accuracy of loss prediction. In particular, the interaction of free-stream turbulence …
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A Detailed Study of Fan-Shaped Film-Cooling for a Nozzle Guide Vane for an Industrial Gas Turbine
… done comparing the performance of two popular turbulence models, the RNG-kε and the v2-f model, in predicting film-cooling effectiveness. Results showed that the RNG-kε offered the closest prediction in terms of averaged effectiveness along the vane surface. The v2-f model more accurately …
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