Enhancement of Film Cooling Effectiveness Using Rectangular Winglet Pair

2018 ◽  
Vol 10 (4) ◽  
Author(s):  
Prakhar Jindal ◽  
Shubham Agarwal ◽  
R. P. Sharma ◽  
A. K. Roy
Keyword(s):  
Film Cooling ◽  
Complete Solution ◽  
Three Dimensional ◽  
Numerical Approach ◽  
Navier Stokes ◽  
Geometrical Parameters ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Enhancement ◽  
The Common

This study deals with the film cooling enhancement in a combustion chamber by the use of rectangular winglet vortex generators (VGs). Rectangular winglet pair (RWP) in both the common-flow up and the common-flow down configuration is installed upstream of a coolant injection hole on the lower chamber wall. A three-dimensional numerical approach with complete solution of Navier–Stokes (NS) equations closed by the k–ɛ turbulence model is used for analyzing the effect of VG installation on film cooling effectiveness enhancement. The effect of RWP orientation is investigated to deduce the best configuration which is then optimized in terms of its geometrical parameters including its upstream distance from the hole and the angle it makes with the incoming flow. Results obtained show that a RWP located upstream of the coolant hole in common-flow down configuration gives the best effectiveness enhancement with certain other geometrical parameters specified. A novel “mushroom” adiabatic distribution scheme for film cooling effectiveness and temperature has been discussed in the paper. This characteristic scheme is developed as a result of RWPs' vortices interaction with the coolant inlet jet and the hot mainstream flow. A detailed discussion of the mechanisms and the flow field properties underlying the effectiveness enhancement and other phenomenon observed has also been presented in the paper.

Analyzes of Film Cooling Effectiveness from Cylindrical and Staggered Compound Cooling Holes with Alignment Angle of 30 Degree at the End of Combustor

2014 ◽  
Vol 695 ◽  
pp. 389-392
Author(s):  
Shahin Salimi ◽  
Nor Azwadi Che Sidik ◽  
Leila Jahanshaloo ◽  
Kianpour Ehsan
Keyword(s):  
Film Cooling ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Internal Cooling ◽  
Ansys Fluent ◽  
Cooling Effectiveness ◽  
Turbine Engine ◽  
Film Cooling Effectiveness ◽  
Alignment Angle ◽  
Compound Angle

A numerical simulation has been performed for the investigation of flow and heat transfer characteristics of a film cooling injected through a hole with cylindrical and compound angle orientation. This paper presents the effects of coolant injector configuration of cylindrical and compound cooling holes with alignment angle of 30 degree at blowing ratio, BR = 3.18 on the film cooling effectiveness near the end wall surface of a combustor simulator. In the current research a three dimensional representation of Pratt and Whitney gas turbine engine was simulated and analyzed with a commercial finite volume package ANSYS FLUENT 14.0. This study has been performed with Reynolds-averaged Navier-Stokes turbulence model (RANS) on internal cooling passages The results indicate that using compound angle cooling holes injection, give much better protection than that obtained when simple angle cooling holes were used.

Numerical Investigation of Scoop Effect on Film Cooling for Cylindrical Inclined Hole

2017 ◽  
Author(s):  
Yongbin Ji ◽  
Prashant Singh ◽  
Srinath V. Ekkad ◽  
Shusheng Zhang
Keyword(s):  
Film Cooling ◽  
Three Dimensional ◽  
Diameter Ratio ◽  
Navier Stokes ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Sst Turbulence Model ◽  
Cooling Behavior ◽  
Length To Diameter Ratio

Film cooling behavior of a single cylindrical hole inclined at an angle of 35° with respect to a flat surface is numerically predicted in this study. Adiabatic film cooling effectiveness has been presented to evaluate the influence of the scoop placed on the coolant entry side. The effect of blowing ratio (0.65, 1, 1.5 and 2) and the length-to-diameter ratio (1.7 and 4.4) are examined. Three-dimensional Reynolds-averaged Navier-Stokes analysis with SST turbulence model is used for the computations. It has been found that both centerline and laterally averaged adiabatic film cooling effectiveness are enhanced by the scoop and the enhancement increases with the blowing ratio in the investigated range of variables. The scoop was more effective for the higher length-to-diameter ratio cases (L/D = 4.4) because of better velocity distribution at the film hole exit, which makes coolant reattach at a more upstream location after blowing off from the wall.

Effects of Curvature on the Film Cooling Effectiveness of Double-Jet Film Cooling

2014 ◽  
Author(s):  
Gaoliang Liao ◽  
Xinjun Wang ◽  
Jun Li ◽  
Feng Zhang
Keyword(s):  
Film Cooling ◽  
Flat Surface ◽  
Three Dimensional ◽  
Curved Surface ◽  
Navier Stokes ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Injection Angle ◽  
Sst Model ◽  
Selection Of

The effect of curvature on the film cooling characteristics of Double-Jet Film Cooling (DJFC) was numerically investigated using three-dimensional Reynolds-Averaged Navier-Stokes (RANS). The low-Reynolds number shear stress transport (SST) model was employed as the turbulence closure model. Six different curved surfaces and a flat surface were tested numerically. The blowing ratios were from 0.66 to 1.99, and the compound injection angle with respect to the cooled surface was 30 degree. The blowing ratios and the curvature of cooled surface have crucial effects on the film cooling effectiveness. The numerical results show that there are two peek value of the averaged film cooling effectiveness along the mainstream direction. The results also indicate that the film cooling effectiveness of a specified curved surface depends on the reasonable selection of the slope of curved surface and blowing ratios.

Numerical Study on Film-Cooling Effectiveness for Various Film-Cooling Hole Schemes

2011 ◽  
Author(s):  
Sun-min Kim ◽  
Ki-Don Lee ◽  
Kwang-Yong Kim
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Cooling Hole ◽  
Influential Parameters

Film-cooling has been widely used as the important alternative to protect the turbine blade. Since the film-cooling hole geometry is one of the most influential parameters for film-cooling performance, various film-cooling hole schemes have been developed to increase cooling performance for the past few decades. In the present work, numerical analysis has been performed to investigate and to compare the film-cooling performance of various film-cooling hole schemes such as fan-shaped, crescent, louver, and dumbbell holes. For analyzes of the turbulent flow and film-cooling, three-dimensional Reynolds-averaged Navier-Stokes analysis has been performed with shear stress transport turbulence model. The validation of numerical results has been performed in comparison with experimental data. The flow characteristics and film-cooling performance for each hole shape have been investigated and evaluated in terms of local- and averaged film-cooling effectivenesses.

Improvement in Film Cooling Effectiveness Using Single and Double Rows of Holes With Adverse Compound Angle Orientations

2018 ◽  
Vol 11 (2) ◽  
Author(s):  
E. Kannan ◽  
Seralathan Sivamani ◽  
D. G. Roychowdhury ◽  
T. Micha Premkumar ◽  
V. Hariram
Keyword(s):  
Film Cooling ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Cylindrical Hole ◽  
Navier Stokes ◽  
Cooling Effectiveness ◽  
Navier Stokes Equations ◽  
Film Cooling Effectiveness ◽  
Turbine Blade Cooling ◽  
Compound Angle

Abstract Three-dimensional Reynolds-averaged Navier–Stokes equations with shear stress transport turbulence model are used to analyze the film cooling effectiveness on a flat plate having single row of film hole involving cylindrical hole (CH) and laidback hole (LBH). The CH and LBH are inclined at 35 deg to the surface with a compound angle (β) orientation ranging from favorable to adverse inclination (i.e., β = 0–180 deg) and examined at high and low blowing ratios (M = 1.25 and 0.60). CH with an adverse compound angle of 135 deg gives the highest area-averaged film cooling effectiveness in comparison with LBH configuration. Also, CH β = 135 deg film hole shows a higher lateral coolant spread. Later, double jet film cooling (DJFC) concept is studied for this CH. In all the cases, the first hole compound angle is fixed as 135 deg, and the second hole angle is varied from 135 deg to 315 deg. At high blowing ratio, the dual jet cylindrical hole (DJCH) with β = 135 deg, 315 deg gives a higher area-averaged film cooling effectiveness by around 66.50% compared to baseline CH β = 0 deg. On comparing all CH, LBH, and DJCH cases, the highest area-averaged film cooling effectiveness is obtained by CH configuration with β = 135 deg. Hence, the CH with its adverse compound angle (β = 135 deg) orientation could be an appropriate film cooling configuration for gas turbine blade cooling.

Assessment of a Double Hole Film Cooling Geometry Using S-PIV and PSP

2013 ◽  
Author(s):  
Lesley M. Wright ◽  
Stephen T. McClain ◽  
Charles P. Brown ◽  
Weston V. Harmon
Keyword(s):  
Film Cooling ◽  
Density Ratio ◽  
Three Dimensional ◽  
Field Measurements ◽  
Secondary Flows ◽  
Cylindrical Hole ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Hole Geometry ◽  
Compound Angle

A novel, double hole film cooling configuration is investigated as an alternative to traditional cylindrical and fanshaped, laidback holes. This experimental investigation utilizes a Stereo-Particle Image Velocimetry (S-PIV) to quantitatively assess the ability of the proposed, double hole geometry to weaken or mitigate the counter-rotating vortices formed within the jet structure. The three-dimensional flow field measurements are combined with surface film cooling effectiveness measurements obtained using Pressure Sensitive Paint (PSP). The double hole geometry consists of two compound angle holes. The inclination of each hole is θ = 35°, and the compound angle of the holes is β = ± 45° (with the holes angled toward one another). The simple angle cylindrical and shaped holes both have an inclination angle of θ = 35°. The blowing ratio is varied from M = 0.5 to 1.5 for all three film cooling geometries while the density ratio is maintained at DR = 1.0. Time averaged velocity distributions are obtained for both the mainstream and coolant flows at five streamwise planes across the fluid domain (x/d = −4, 0, 1, 5, and 10). These transverse velocity distributions are combined with the detailed film cooling effectiveness distributions on the surface to evaluate the proposed double hole configuration (compared to the traditional hole designs). The fanshaped, laidback geometry effectively reduces the strength of the kidney-shaped vortices within the structure of the jet (over the entire range of blowing ratios considered). The three-dimensional velocity field measurements indicate the secondary flows formed from the double hole geometry strengthen in the plane perpendicular to the mainstream flow. At the exit of the double hole geometry, the streamwise momentum of the jets is reduced (compared to the single, cylindrical hole), and the geometry offers improved film cooling coverage. However, moving downstream in the steamwise direction, the two jets form a single jet, and the counter-rotating vortices are comparable to those formed within the jet from a single, cylindrical hole. These strong secondary flows lift the coolant off the surface, and the film cooling coverage offered by the double hole geometry is reduced.

Film Cooling From Novel Sister Shaped Single-Holes

2014 ◽  
Author(s):  
Siavash Khajehhasani ◽  
Bassam Jubran
Keyword(s):  
Film Cooling ◽  
Three Dimensional ◽  
Lateral Spreading ◽  
Navier Stokes ◽  
The Novel ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Shaped Hole ◽  
Lift Off

A numerical investigation of the film cooling performance from novel sister shaped single-holes (SSSH) is presented in this paper and the obtained results are compared with a single cylindrical hole, a forward diffused shaped hole, as well as discrete sister holes. Three types of the novel sister shaped single-hole schemes namely downstream, upstream and up/downstream SSSH, are designed based on merging the discrete sister holes to the primary hole in order to reduce the jet lift-off effect and increase the lateral spreading of the coolant on the blade surface as well as a reduction in the amount of coolant in comparison with discrete sister holes. The simulations are performed using three-dimensional Reynolds-Averaged Navier Stokes analysis with the realizable k–ε model combined with the standard wall function. The upstream SSSH demonstrates similar film cooling performance to that of the forward diffused shaped hole for the low blowing ratio of 0.5. While it performs more efficiently at M = 1, where the centerline and laterally averaged effectiveness results improved by 70% and 17%, respectively. On the other hand, the downstream and up/downstream SSSH schemes show a considerable improvement in film cooling performance in terms of obtaining higher film cooling effectiveness and less jet lift-off effect as compared with the single cylindrical and forward diffused shaped holes for both blowing ratios of M = 0.5 and 1. For example, the laterally averaged effectiveness for the downstream SSSH configuration shows an improvement of approximately 57% and 110% on average as compared to the forward diffused shaped hole for blowing ratios of 0.5 and 1, respectively.

Leading Edge Film Cooling: Computations and Experiments Including Density Effects

1996 ◽  
Author(s):  
Pingfan He ◽  
Dragos Licu ◽  
Martha Salcudean ◽  
Ian S. Gartshore
Keyword(s):  
Experimental Data ◽  
Film Cooling ◽  
Stokes Equations ◽  
Leading Edge ◽  
Variable Density ◽  
Navier Stokes ◽  
Cooling Effectiveness ◽  
Stagnation Line ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio

The effect of varying coolant density on film cooling effectiveness for a turbine blade-model was numerically investigated and compared with experimental data. This model had a semi-circular leading edge with four rows of laterally-inclined film cooling orifices positioned symmetrically about the stagnation line. A curvilinear coordinate-based CFD code was developed and used for the numerical investigation. The code used a domain segmentation strategy in conjunction with general curvilinear grids to model the complex blade configuration. A multigrid method was used to accelerate the convergence rate. The time-averaged, variable-density, Navier-Stokes equations together with the energy or scalar equation were solved. Turbulence closure was attained by the standard k–ε model with a near-wall k model. Either air or CO2 was used as coolant in three cases of injection through single rows and alternatively staggered double raws of holes. Two different blowing rates were investigated in each case and compared with experimental data. The experimental results were obtained using a wind tunnel model, and the mass/heat analogy was used to determine the film cooling effectiveness. The higher density of the carbon dioxide coolant (approximately 1.5 times the density of air) in the isothermal mass injection experiments, was used to simulate the effects of injection of a colder air in the corresponding adiabatic heat transfer situation. Good agreement between calculated and measured film cooling effectiveness was found for low blowing ratio M ≤ 0.5 and the effect of density was not significant. At higher blowing ratio M > 1 the calculations consistently overpredict the measured values of film cooling effectiveness.

scholarly journals Heat Transfer on a Film-Cooled Rotating Blade

1999 ◽  
Author(s):  
Vijay K. Garg
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Three Dimensional ◽  
Leading Edge ◽  
Tip Clearance ◽  
Navier Stokes ◽  
Film Cooling Effectiveness ◽  
Film Cooling Holes

A multi-block, three-dimensional Navier-Stokes code has been used to compute heat transfer coefficient on the blade, hub and shroud for a rotating high-pressure turbine blade with 172 film-cooling holes in eight rows. Film cooling effectiveness is also computed on the adiabatic blade. Wilcox’s k-ω model is used for modeling the turbulence. Of the eight rows of holes, three are staggered on the shower-head with compound-angled holes. With so many holes on the blade it was somewhat of a challenge to get a good quality grid on and around the blade and in the tip clearance region. The final multi-block grid consists of 4784 elementary blocks which were merged into 276 super blocks. The viscous grid has over 2.2 million cells. Each hole exit, in its true oval shape, has 80 cells within it so that coolant velocity, temperature, k and ω distributions can be specified at these hole exits. It is found that for the given parameters, heat transfer coefficient on the cooled, isothermal blade is highest in the leading edge region and in the tip region. Also, the effectiveness over the cooled, adiabatic blade is the lowest in these regions. Results for an uncooled blade are also shown, providing a direct comparison with those for the cooled blade. Also, the heat transfer coefficient is much higher on the shroud as compared to that on the hub for both the cooled and the uncooled cases.

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