A Parametric Numerical Study of the Effects of Freestream Turbulence Intensity and Length Scale on Anti-Vortex Film Cooling Design at High Blowing Ratio

Repko, Timothy W.; Nix, Andrew C.; Heidmann, James D.

doi:10.1115/ht2013-17255

Cited by 7 publications

(10 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The current study presents the results of numerical study to visualize a multi-hole concept, the anti-vortex hole (AVH) that has been documented in previous studies [5]- [7]. The anti-vortex hole concept is shown in the current study as well as the previous studies to have its performance enhanced with elevated mainstream turbulence levels.…”

Section: Introductionmentioning

confidence: 82%

“…Results from Repko et al [5] showed that varying the turbulent length scale does not have a major effect on the cooling effectiveness of the AVH, resulting in a reduction in the number of cases that are needed for comparison of different turbulence levels. Three different cases of varying turbulence intensity were studied by using both steady and unsteady Reynolds Averaged Navier Stokes (RANS and URANS) solvers in order to be able to analyze and compare the differences in the flow predictions by two different solution techniques.…”

Section: Numerical Studymentioning

confidence: 99%

“…The control volume used was identical to the ones used in previous work [5]- [9], for the ease of direct comparison of the results. This control volume is determined such that the region of influence of a single hole is successfully encompassed.…”

Section: Film Cooling Geometrymentioning

confidence: 99%

“…A turbulence intensity of 1% and a length scale normalized by main cooling hole diameter of 1.0 was specified for the plenum. A Reynolds number based on the main film cooling hole diameter and mainstream flow conditions of 11,300 was matched to previous work [5] [8] [9].…”

Section: Numerical Simulation Parametersmentioning

confidence: 99%

See 3 more Smart Citations

Flow Visualization of Multi-Hole Film-Cooling Flow under Varying Freestream Turbulence Levels

Repko¹,

Nix²,

Uysal³

et al. 2016

JFCMV

Self Cite

View full text Add to dashboard Cite

A flat plate film cooling flow from a multi-exit hole configuration has been numerically simulated using both steady and unsteady Reynolds Averaged Navier Stokes (RANS and URANS) Computational Fluid Dynamics (CFD) formulations. This multi-exit hole concept, the Anti-Vortex Hole (AVH), has been developed and studied by previous research groups and shown to mitigate or counter the vorticity generated by conventional holes resulting in a more attached film cooling layer and higher film cooling effectiveness. The film cooling jets interaction with the free stream flow is a long studied area in gas turbine heat transfer. The present study numerically simulates the jet interaction with the multi-exit hole concept at a high blowing ratio (M = 2.0) and density ratio (DR = 2.0) in order to provide a more detailed, graphical explanation of the improvement in film cooling effectiveness. This paper presents a numerical study of the flow visualization of the interaction of film cooling jets with a subsonic crossflow. The contour plots of adiabatic cooling effectiveness were used to compare the multi-exit hole and conventional single hole configurations. The vortex structures in the flow were analyzed by URANS formulations and the effect of these vortices on the cooling effectiveness was investigated together with the coolant jet lift-off predictions. Quasi-Instantaneous Temperature Isosurface plots are used in the investigations of the effect of turbulence intensity on the cooling effectiveness and coolant jet coverage. The effect of varying turbulence intensity was investigated when analyzing the jets' interaction with the cross flow and the corresponding temperatures at the wall. The results show that as the turbulence intensity is increased, the cooling flow will stay more attached to the wall and have more pronounced lateral spreading far downstream of the cooling holes.

show abstract

Section: Introductionmentioning

confidence: 82%

Section: Numerical Studymentioning

confidence: 99%

Section: Film Cooling Geometrymentioning

confidence: 99%

Section: Numerical Simulation Parametersmentioning

confidence: 99%

See 2 more Smart Citations

Flow Visualization of Multi-Hole Film-Cooling Flow under Varying Freestream Turbulence Levels

Repko¹,

Nix²,

Uysal³

et al. 2016

JFCMV

Self Cite

View full text Add to dashboard Cite

show abstract

“…In fact, real gas turbine engines are frequently run under Tu by about 10% to 20%, as predicted by Mayhew et al [19]. Effects of Tu on the performance of film cooling of the turbine vanes and blades, flat plate, and cylindrical leading-edge models were numerically and experimentally investigated by many groups of researchers [20][21][22][23][24][25][26][27][28]. However, few experimental and numerical studies have hitherto been focused on a real situation regarding the cooling performances of turbine airfoils from simultaneous effects of TBC and Tu.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Cooling Performances of a Non-Film-Cooled Turbine Vane Coated with a Thermal Barrier Coating Using Conjugate Heat Transfer

et al. 2018

View full text Add to dashboard Cite

Abstract:The aim of this paper is to numerically investigate cooling performances of a non-film-cooled turbine vane coated with a thermal barrier coating (TBC) at two turbulence intensities (Tu = 8.3% and 16.6%). Computational fluid dynamics (CFD) with conjugate heat transfer (CHT) analysis is used to predict the surface heat transfer coefficient, overall and TBC effectiveness, as well as internal and average temperatures under a condition of a NASA report provided by Hylton et al. [NASA CR-168015]. The following interesting phenomena are observed: (1) At each Tu, the TBC slightly dampens the heat transfer coefficient in general, and results in the quantitative increment of overall cooling effectiveness about 16-20%, but about 8% at the trailing edge (TE). (2) The protective ability of the TBC increases with Tu in many regions, that is, the leading edge (LE) and its neighborhoods on the suction side (SS), as well as the region from the LE to the front of the TE on the pressure side (PS), because the TBC causes the lower enhancement of the heat transfer coefficient in general at the higher Tu. (3) Considering the internal and average temperatures of the vane coated with two different TBCs, although the vane with the lower thermal conductivity protects more effectively, its role in the TE region reduces more significantly. (4) For both TBCs, the increment of Tu has a relatively small effect on the reduction of the average temperature of the vane.

show abstract

Experimental investigation of the influence of freestream turbulence on an anti-vortex film cooling hole

Hayes

Nix

Nestor

et al. 2017

Experimental Thermal and Fluid Science

Self Cite

View full text Add to dashboard Cite

Film cooling is used in gas turbines to thermally protect combustor and turbine hot section components by creating a layer of relatively cooler air to insulate the components from the hot freestream gases. This relatively cooler air is taken from upstream in the compressor section at a loss to the engine efficiency and therefore must be used as effectively as possible. A novel anti-vortex hole (AVH) geometry has been investigated experimentally through a transient infrared thermography technique to study the film cooling effectiveness and heat transfer coefficient by varying blowing ratio and freestream turbulence intensity. The AVH geometry is designed with two secondary holes stemming from a main cooling hole that attempts to diffuse the coolant jet and mitigate the vorticity produced by conventional straight holes. The AVH geometry data collected showed improved cooling performance at low freestream turbulence intensities compared to conventional straight holes. Three turbulence intensities of 1, 7.5, and 11.7% were investigated for the AVH geometry at blowing ratios of 0.5, 1.0, 1.5, and 2.0 for a total of twelve different conditions. Results showed that higher freestream turbulence conditions were beneficial to the performance of the AVH. Increasing the blowing ratio at all turbulence levels also improved film cooling effectiveness, both span-averaged and on the centerline. The highest performing case was at a turbulence intensity of 7.5% and a blowing ratio of 2.0. The 11.7% cases outperformed the 1% cases, but it appears that at the 11.7% cases the higher freestream turbulence reduces the performance of the secondary holes compared to the 7.5% case. Increasing the blowing ratio and turbulence intensity will result in a higher heat transfer coefficient, which must be taken into account for future designs and overall reduction of heat load.

show abstract

A Parametric Numerical Study of the Effects of Freestream Turbulence Intensity and Length Scale on Anti-Vortex Film Cooling Design at High Blowing Ratio

Cited by 7 publications

References 0 publications

Flow Visualization of Multi-Hole Film-Cooling Flow under Varying Freestream Turbulence Levels

Flow Visualization of Multi-Hole Film-Cooling Flow under Varying Freestream Turbulence Levels

Investigation of Cooling Performances of a Non-Film-Cooled Turbine Vane Coated with a Thermal Barrier Coating Using Conjugate Heat Transfer

Experimental investigation of the influence of freestream turbulence on an anti-vortex film cooling hole

Contact Info

Product

Resources

About