Experimental and numerical study on the flame characteristics and cooling effectiveness of air-cooled flame holder

Energy ◽  
2020 ◽  
Vol 209 ◽  
pp. 118421
Author(s):  
Zhao Shilong ◽  
Fan Yuxin
Keyword(s):  
Numerical Study ◽  
Cooling Effectiveness ◽  
Flame Holder

Numerical Study of the Effect of Blowing Angle on Cooling Effectiveness of an Effusion Cooling

2004 ◽  
Author(s):  
Yaping Hu ◽  
Honghu Ji
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Coolant Flow ◽  
Cooling Effectiveness ◽  
Absolute Value ◽  
Blowing Ratio ◽  
Conventional Film

The paper numerically investigates the influences of the blowing angle α of coolant flow on the cooling effectiveness of effusion cooling of a plate. Nine cases were studied which cover three blowing angles of α = 30°, 60°, 90° and for each angle three blowing ratios of M = 0.5, 1.0, 2.0 are calculated, respectively. The results show that with the increase of α the cooling effectiveness reduces for all the calculated cases. For the cases of α = 30° and 60° the distribution of cooling effectiveness η along the whole plate are very similar for any given blowing ratio, especially when M = 1.0 and 2.0. Whereas for the cases of α = 90°, the distributions of cooling effectiveness are quite different from other two blowing angles for a given blowing ratio, especially for M = 1.0 and in the trailing region of the plate. Although the cooling effectiveness of the cases with α = 90° for any given blowing ratio is the worst one among the three angles (α = 30°, 60°, and 90°) stated, its absolute value is still quite high comparing to the conventional film cooling.

Numerical Investigation of Effects of Blockage, Inclination Angle, and Hole-Size on Film Cooling Effectiveness at Concave Surface

2021 ◽  
Vol 143 (2) ◽  
Author(s):  
Fu-qiang Wang ◽  
Jian Pu ◽  
Jian-hua Wang ◽  
Wei-dong Xia
Keyword(s):  
Film Cooling ◽  
Pressure Loss ◽  
Numerical Study ◽  
Density Ratio ◽  
Concave Surface ◽  
Blockage Ratio ◽  
Coverage Area ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Injection Angle

Abstract Film-hole can be often blocked by thermal-barrier coatings (TBCs) spraying, resulting in the variations of aerodynamic and thermal performances of film cooling. In this study, a numerical study of the blockage effect on the film cooling effectiveness of inclined cylindrical-holes was carried out on a concave surface to simulate the airfoil pressure side. Three typical blowing ratios (BRs) of 0.5, 1.0, and 1.5 were chosen at an engine-similar density ratio (DR) of 2.0. Two common inclination angles of 30 deg and 45 deg were designed. The blockage ratios were adjusted from 0 to 20%. The results indicated the blockage could enhance the penetration of film cooling flow to the mainstream. Thus, the averaged effectiveness and coolant coverage area were reduced. Moreover, the pressure loss inside of the hole was increased. With the increase of BR, the decrement of film cooling effectiveness caused by blockage rapidly increased. At BR = 1.5, the decrement could be acquired up to 70% for a blockage ratio of 20%. The decrement of film cooling effectiveness caused by blockage was nearly nonsensitive to the injection angle; however, the larger angle could generate the higher increment of pressure loss caused by blockage. A new design method for the couple scheme of film cooling and TBC was proposed, i.e., increasing the inlet diameter according to the blockage ratio before TBC spraying. In comparison with the original unblocked-hole, the enlarged blocked-hole not only kept the nearly same area-averaged effectiveness but also reduced slightly the pressure loss inside of the hole. Unfortunately, application of enlarged blocked-hole at large BR could lead to a more obvious reduction of effectiveness near hole-exit, in comparison with the original common-hole.

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

2013 ◽  
Author(s):  
Timothy W. Repko ◽  
Andrew C. Nix ◽  
James D. Heidmann
Keyword(s):  
Turbulence Intensity ◽  
Film Cooling ◽  
Numerical Study ◽  
Length Scale ◽  
Freestream Turbulence ◽  
Cooling Effectiveness ◽  
Length Scales ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Cooling Design

An advanced, high-effectiveness film-cooling design, the anti-vortex hole (AVH) has been investigated by several research groups and shown to mitigate or counter the vorticity generated by conventional holes and increase film effectiveness at high blowing ratios and low freestream turbulence levels. [1, 2] The effects of increased turbulence on the AVH geometry were previously investigated and presented by researchers at West Virginia University (WVU), in collaboration with NASA, in a preliminary CFD study [3] on the film effectiveness and net heat flux reduction (NHFR) at high blowing ratio and elevated freestream turbulence levels for the adjacent AVH. The current paper presents the results of an extended numerical parametric study, which attempts to separate the effects of turbulence intensity and length-scale on film cooling effectiveness of the AVH. In the extended study, higher freestream turbulence intensity and larger scale cases were investigated with turbulence intensities of 5, 10 and 20% and length scales based on cooling hole diameter of Λx/dm = 1, 3 and 6. Increasing turbulence intensity was shown to increase the centerline, span-averaged and area-averaged adiabatic film cooling effectiveness. Larger turbulent length scales were shown to have little to no effect on the centerline, span-averaged and area-averaged adiabatic film-cooling effectiveness at lower turbulence levels, but slightly increased effect at the highest turbulence levels investigated.

Enhancement of Full Coverage Film Cooling Effectiveness with Mixed Injection Holes

2018 ◽  
Vol 0 (0) ◽  
Author(s):  
Mukesh Prakash Mishra ◽  
A K Sahani ◽  
Sunil Chandel ◽  
R K Mishra
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Velocity Ratio ◽  
Perforated Plate ◽  
Combustion Chambers ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Full Coverage ◽  
Upstream Direction ◽  
The Difference

Abstract In the present work numerical study of full coverage film cooling on an adiabatic flat plate is carried out. Cooling performance of three configurations of cylindrical holes is studied with downstream injection, upstream injection and mixed injection. In mixed injection configuration one column of holes inject in downstream direction and the holes in the adjacent column inject in the upstream direction. Numerical simulations are carried out at different velocity ratios and circumferentially averaged value of adiabatic film cooling effectiveness is estimated. Simulation results indicate that the mixed injection configuration has better and more uniform cooling, throughout the perforated plate, than with downstream injection. The difference is greater with increase in the velocity ratio. Configuration with upstream injection gives better cooling than mixed injection at front few rows of cooling holes but it shows poorer performance with downstream injection in the downstream rows of cooling holes. The obtained results from this study can be an invaluable input for highly loaded combustion chambers.

Numerical Study on the Influence of Trench Width on Film Cooling Characteristics of Double-Wave Trench

2017 ◽  
Author(s):  
Bo-lun Zhang ◽  
Li Zhang ◽  
Hui-ren Zhu ◽  
Jian-sheng Wei ◽  
Zhong-yi Fu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Numerical Study ◽  
Leading Edge ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Trench Width

Film cooling performance of the double-wave trench was numerically studied to improve the film cooling characteristics. Double-wave trench was formed by changing the leading edge and trailing edge of transverse trench into cosine wave. The film cooling characteristics of transverse trench and double-wave trench were numerically studied using Reynolds Averaged Navier Stokes (RANS) simulations with realizable k-ε turbulence model and enhanced wall treatment. The film cooling effectiveness and heat transfer coefficient of double-wave trench at different trench width (W = 0.8D, 1.4D, 2.1D) conditions are investigated, and the distribution of temperature field and flow field were analyzed. The results show that double-wave trench effectively improves the film cooling effectiveness and the uniformity of jet at the downstream wall of the trench. The span-wise averaged film cooling effectiveness of the double-wave trench model increases 20–63% comparing with that of the transverse trench at high blowing ratio. The anti-counter-rotating vortices which can press the film on near-wall are formed at the downstream wall of the double-wave trench. With the double-wave trench width decreasing, the film cooling effectiveness gradually reduces at the hole center-line region of the downstream trench. With the increase of the blowing ratio, the span-wise averaged heat transfer coefficient increases. The span-wise averaged heat transfer coefficient of the double-wave trench with 0.8D and 2.1D trench width is higher than that of the double-wave trench with 1.4D trench width at the high blowing ratio conditions.

Numerical Study of Heat Transfer and Cooling Effectiveness on a Flat-Tip Turbine Blade

2013 ◽  
Author(s):  
Qihe Huang ◽  
Jiao Wang ◽  
Lei He ◽  
Qiang Xu
Keyword(s):  
Heat Transfer ◽  
Turbine Blade ◽  
Film Cooling ◽  
Numerical Study ◽  
Leakage Flow ◽  
Tip Leakage Flow ◽  
Cooling Effectiveness ◽  
Blowing Ratio ◽  
Flow And Heat Transfer ◽  
Blade Tip

A numerical study is performed to simulate the tip leakage flow and heat transfer on the first stage rotor blade tip of GE-E3 turbine, which represents a modern gas turbine blade geometry. Calculations consist of the flat blade tip without and with film cooling. For the flat tip without film cooling case, in order to investigate the effect of tip gap clearance on the leakage flow and heat transfer on the blade tip, three different tip gap clearances of 1.0%, 1.5% and 2.5% of the blade span are considered. And to assess the performance of the turbulence models in correctly predicting the blade tip heat transfer, the simulations have been performed by using four different models (the standard k-ε, the RNG k-ε, the standard k-ω and the SST models), and the comparison shows that the standard k-ω model provides the best results. All the calculations of the flat tip without film cooling have been compared and validated with the experimental data of Azad[1] and the predictions of Yang[2]. For the flat tip with film cooling case, three different blowing ratio (M = 0.5, 1.0, and 1.5) have been studied to the influence on the leakage flow in tip gap and the cooling effectiveness on the blade tip. Tip film cooling can largely reduce the overall heat transfer on the tip. And the blowing ratio M = 1.0, the cooling effect for the blade tip is the best.

Injection Angle Influence of Secondary Holes on the Enhancement of Film Cooling Effectiveness With Horn-Shaped or Cylindrical Primary Holes

2017 ◽  
Author(s):  
Rui Zhu ◽  
Gongnan Xie ◽  
Terrence W. Simon
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Cylindrical Hole ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Injection Angle ◽  
Inclination Angles ◽  
Cooling Hole ◽  
Cylindrical Holes

Secondary holes to a main film cooling hole are used to improve film cooling performance by creating anti-kidney vortices. The effects of injection angle of the secondary holes on both film cooling effectiveness and surrounding thermal and flow fields are investigated in this numerical study. Two kinds of primary hole shapes are adopted. One is a cylindrical hole, the other is a horn-shaped hole which is designed from a cylindrical hole by expanding the hole in the transverse direction to double the hole size at the exit. Two smaller cylindrical holes, the secondary holes, are located symmetrically about the centerline and downstream of the primary hole. Three compound injection angles (α = 30°, 45° and 60°, β = 30°) of the secondary holes are analyzed while the injection angle of the primary hole is kept at 45°. Cases with various blowing ratios are computed. It is shown from the simulation that cooling effectiveness of secondary holes with a horn-shaped primary hole is better than that with a cylindrical primary hole, especially at high blowing ratios. With a cylindrical primary hole, increasing inclination angle of the secondary holes provides better cooling effectiveness because the anti-kidney vortices created by shallow secondary holes cannot counteract the kidney vortex pairs adequately, enhancing mixing of main flow and coolant. For secondary holes with a horn-shaped primary hole, large secondary hole inclination angles provide better cooling performance at low blowing ratios; but, at high blowing ratios, secondary holes with small inclination angles are more effective, as the film coverage becomes wider in the downstream area.

Numerical Study of Impingement and Film Composite Cooling on Blade Leading Edge

2014 ◽  
Author(s):  
Zhao Liu ◽  
Lv Ye ◽  
Zhenping Feng
Keyword(s):  
Shear Stress ◽  
Nusselt Number ◽  
Numerical Study ◽  
Density Ratio ◽  
Leading Edge ◽  
Cooling Effectiveness ◽  
Simulation Accuracy ◽  
Film Composite ◽  
Blowing Ratio ◽  
Shear Stress Transport

In this paper a numerical study is performed to simulate the impingement and film composite cooling on the first stage rotor blade of GE-E3 engine high pressure turbine. A commercial CFD software CFX11.0 with a 3D RANS approach is adopted in the study. Firstly, by comparing with available experimental data, the relative performance of four turbulence models for numerical impingement and film composite cooling is studied, including the standard k-ε model, the RNG k-ε model, the standard k-ω model and the Shear-Stress Transport k-ω model. The Shear-Stress Transport k-ω model is chosen for the numerical study as it shows the best simulation accuracy. Then the simulations consist of five different density ratios (1.16∼4.81) and seven different blowing ratios (0.5∼3.0). The results indicate that the cooling effectiveness on pressure side is lower than that on the suction side. The cooling effectiveness increases with the increase of blowing ratio in the study range, but decreases with the increase of density ratio. On the target surface, the average Nusselt number, the circumferential averaged Nusselt number and its peak value increase with the increasing in blowing ratio, but decrease with the increase of density ratio.

A Numerical Study of 3D Turbulent Cooling Jet Interaction Over a Range of Blowing Ratios, Turbulence Intensity and Turbulent Length Scale

2005 ◽  
Author(s):  
Jon Ratzlaff ◽  
Paul D. Orkwis ◽  
Balu Sekar
Keyword(s):  
Turbulence Intensity ◽  
Numerical Study ◽  
Length Scale ◽  
Exit Plane ◽  
Cooling Effectiveness ◽  
Turbulent Length Scale ◽  
Corner Separation ◽  
Cooling Flows ◽  
Blowing Ratio ◽  
Total Temperature

Three-dimensional simulations of an unloaded cooled vane have been conducted for blowing ratios of 0.67, 1.02, and 1.4. For each blowing ratio, three free stream turbulence intensities of 1%, 10%, and 20% have been simulated. A brief investigation into the effects of length scale has also been performed at a turbulence intensity of 10% via a 40% reduction in length scale of. Three rows of cooling holes were simulated for a total of 31 cooling holes. The flow through each hole and the feed plenum were simulated. The first two rows of holes were inclined downward at 60° to the horizon, while the third row exited axially. The cases were run at Mach number 0.23 and Reynolds number based on the blade leading edge diameter, or thickness, of 4.1×104 with a main flow total temperature of 705.6K° and a cooling flow total temperature of 360K°, providing a cold to hot gas density ratio of approximately 2. Surface contours of film cooling effectiveness and static temperature, plots of η vs. s, exit plane static temperature contours, and exit plane plots of mass averaged total temperature are presented along with detailed streamline maps to show the propagation of cooling flows through the passage. The results indicate that cooling effectiveness was greatest for the 1.02 blowing ratio case. Higher blowing ratios resulted in streaks of uncooled blade surface between cooling holes in the showerhead region caused by cooling jet coupling and interactions, and the misplacement of the holes for this condition. These cooling patterns resulted in a cell-like structure of cooling flows in the downstream wake for the lowest turbulence intensity, although this was not observed with higher turbulence. Lastly, cooling flows impacted the lower wall of the passage for all cases. This occurred when cooling flows were either entrained by the corner separation for the two lower blowing ratio cases, or impacted the lower surface before the separation, as observed for high blowing and low turbulence. In the latter case this resulted in suppression of the corner separation in the trailing edge region of the blade.

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