Effects of High Intensity, Large-Scale Freestream Combustor Turbulence on Heat Transfer in Transonic Turbine Blades

Nix, Andrew C.; Diller, Thomas E.; Ng, Wing F.

doi:10.21236/ada419523

Cited by 5 publications

(4 citation statements)

References 55 publications

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“…By performing highly resolved simulations with up to grid points, the flow physics can be investigated in detail. In particular, the effects of the FST with strong intensities and large integral length scales, which resemble the flow conditions in realistic applications (Nix 2004), will be discussed. In the present simulations, the FST and the boundary layer are significantly affected by the strong pressure gradient and high curvature around the blade, which makes the boundary layer transition more challenging to understand.…”

Section: Introductionmentioning

confidence: 99%

Bypass transition in boundary layers subject to strong pressure gradient and curvature effects

Zhao

Sandberg

2020

J. Fluid Mech.

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Section: Introductionmentioning

confidence: 99%

Bypass transition in boundary layers subject to strong pressure gradient and curvature effects

Zhao

Sandberg

2020

J. Fluid Mech.

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“…This is expected to also vary the resulting turbulence length scale of the inlet condition, however, this effect was not discussed. In an effort to get closer to engine-like turbulence intensities, Nix [3] showed experimentally that increasing Tu from 2% to 16% increased the pressure side heat transfer by 50% while having little impact on the suction side surface. This suggests that the strong acceleration of the flow on the suction side reduced the local turbulence intensity to amplitudes sufficiently low so that the transition behavior was not affected.…”

Section: Introductionmentioning

confidence: 99%

High-Fidelity Simulations of a Linear HPT Vane Cascade Subject to Varying Inlet Turbulence

Pichler

Sandberg

Laskowski

et al. 2017

Volume 2A: Turbomachinery

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The effect of inflow turbulence intensity and turbulence length scales have been studied for a linear high-pressure turbine vane cascade at Reis = 590,000 and Mis = 0.93, using highly resolved compressible large-eddy simulations employing the WALE turbulence model. The turbulence intensity was varied between 6% and 20% while values of the turbulence length scales were prescribed between 5% and 20% of axial chord. The analysis focused on characterizing the inlet turbulence and quantifying the effect of the inlet turbulence variations on the vane boundary layers, in particular on the heat flux to the blade. The transition location on the suction side of the vane was found to be highly sensitive to both turbulence intensity and length scale, with the case with turbulence intensity 20% and 20% length scale showing by far the earliest onset of transition and much higher levels of heat flux over the entire vane. It was also found that the transition process was highly intermittent and local, with spanwise parts of the suction side surface of the vane remaining laminar all the way to the trailing edge even for high turbulence intensity cases.

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“…The perturbation of the inputs was based on the manufacturing specifications of each transducer used in the experiment [51]. Precision uncertainty is associated with the randomness or variation of run-to-run measurements taken in the experiment [52]. Both types of uncertainty were calculated in a MATLAB ® script that simultaneously collected and averaged data from the data files created by the DAQ software.…”

Section: Uncertainty Analysismentioning

confidence: 99%

An Experimental Comparison of the Performance of Two Impulse Micro-Hydro Turbine Impellers

Matheny¹

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The goal of this project was to measure the performance of two micro-hydro Turgo Impulse Turbine Impellers. In 2014, Hydropower accounted for 6% of total electric power produced and 48% of electricity produced by renewable sources in the United States. Micro-hydro power is an established, robust, and versatile technology that can help society produce electric power without the emission of greenhouse gases and with minimal environmental impact. Competition from other renewable energy sources is causing the operational efficiency and power production of microhydro turbines to become increasingly important. This competition puts pressure on manufacturers to improve the quality of their turbine designs and manufacturing methods. Computational fluid dynamics (CFD), combined with numerical methods and increased computing power, have become more widely used tools in the past several decades for design improvement. However, empirically derived performance data is still needed to validate modeling improvements and support further development of hydropower technology. Two impellers were chosen for study because they were used in an operational turbine system that the experiments were modeled after. The first impeller was designed and partially manufactured by Hartvigsen Hydro and assembled by Preston Machine, Inc. The second impeller had been in operation in the turbine system for several years and showed signs of wear. The blades on the two impellers were shaped very differently due to having completely different manufacturers. A test setup was designed and constructed to measure the overall efficiency and power output of both impellers. Two types of performance experiments were conducted. The first experiment determined the most efficient setting for the inlet nozzles which are used to increase the kinetic energy of the water prior to impinging on the turbine impeller. The second experiment measured the efficiency and power output of each impeller while varying the flow rate and shaft speed for each of two impellers. The results were analyzed and displayed as three dimensional maps for graphical interpretation of turbine performance as conditions were varied. The experiments indicate that the new impeller (impeller A) operated most efficiently with a peak efficiency 84.6% (with mechanical losses excluded). The older impeller (impeller B) reached a peak efficiency of 74.8%. Both impellers produced approximately the same amount of shaft power (28.6 hp with mechanical losses included) at their peak operating points. The experiments indicated that both turbines were sensitive to varying conditions and properly managing those conditions is necessary to obtain reliable and efficient energy output over a long operational lifetime.

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Effects of High Intensity, Large-Scale Freestream Combustor Turbulence on Heat Transfer in Transonic Turbine Blades

Cited by 5 publications

References 55 publications

Bypass transition in boundary layers subject to strong pressure gradient and curvature effects

Bypass transition in boundary layers subject to strong pressure gradient and curvature effects

High-Fidelity Simulations of a Linear HPT Vane Cascade Subject to Varying Inlet Turbulence

An Experimental Comparison of the Performance of Two Impulse Micro-Hydro Turbine Impellers

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