scholarly journals Effects of Various Injection Holes with/without Opening Angles of Film Cooling on Blades of Gas Turbine: A CFD Approach

2021 ◽  
Vol 18 (22) ◽  
pp. 452
Author(s):  
Ebrahim Hosseini
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Flow Characteristics ◽  
Navier Stokes ◽  
Recirculation Region ◽  
Opening Angle ◽  
Cooling Efficiency ◽  
Injection Hole ◽  
Ansys Fluent ◽  
Cooling Performance

The combustor exit temperature is steadily rising to improve the overall efficiency of the gas turbine. As a result, film cooling, the most important and necessary cooling technology, must be developed further to satisfy this demanding requirement. The film cooling performance on the NACA 0012 gas turbine blade is numerically evaluated in this research using 6 different injection holes with and without opening angles. The Computational Fluid Dynamics (CFD) software Ansys Fluent v16 is used to conduct 2-dimensional Reynolds-Averaged Navier-Stokes (RANS) flow and heat transfer analyses. The flow is assumed to be steady, turbulent, and incompressible. To obtain solutions, the incompressible RANS equations are solved using the finite-volume technique. The simulation results indicate that the SST k-ω turbulence model is appropriate for simulating flow characteristics and evaluating film cooling efficiency over the blade. Furthermore, the opening angle has a beneficial impact on the upper blade surface's cooling performance. The injection hole with an opening angle of 15º and a height of D (injection hole diameter) achieves the maximum value of cooling efficiency. The coolant injected from the hole provides greater cooling coverage for the entire blade in this configuration, increasing cooling effectiveness. HIGHLIGHTS The influence of various geometries of injection holes on the effectiveness of film cooling was investigated The low opening angle has a greater impact on film cooling than the other opening angles The injection hole with an opening angle eliminates the recirculation region after the coolant exits GRAPHICAL ABSTRACT

Film cooling modeling of a gas turbine blade by considering different injection holes with and without opening angles through CFD

2021 ◽  
Vol 15 (1) ◽  
pp. 7637-7647
Author(s):  
E. Hosseini
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Film Cooling ◽  
High Performance ◽  
Turbine Blades ◽  
Flow Characteristics ◽  
Opening Angle ◽  
Inlet Temperature ◽  
Cooling Efficiency ◽  
Gas Turbine Blade

One way to achieve high performance in the gas turbine is to increase the inlet temperature of the turbine. Different cooling techniques have been carried out in order to protect the turbine blades which have been exposed to such high temperatures. Film cooling as an essential cooling method needs to be enhanced to meet the challenging demand. The purpose of the present research is to analyze the film cooling performance over a NACA 0012 gas turbine blade using six different injection holes with and without opening angles, separately through Computational Fluid Dynamics (CFD). 2D Reynolds-Averaged Navier-Stokes (RANS) equations are implemented to consider the heat transfer and flow characteristics by using CFD code Ansys Fluent v16. The flow is considered as steady, turbulent, and incompressible. The RANS equation is solved with the finite-volume method for obtaining solutions. The simulation results revealed that the k-ω SST turbulence model is suitable for simulating the flow characteristics and analyzing the performance of film cooling over the blade. Also, the opening angle has a significant effect on increasing the cooling efficiency for the upper blade surface. The highest value of cooling efficiency is obtained by the injection hole with an opening angle of 15° and height of D. In this configuration, the coolant injected from hole provides better cooling coverage for the entire blade which increases the cooling effectiveness.

Effects of a Groove Patterned Cooling Tube on the Film Cooling Performance of a Gas Turbine Blade

2017 ◽  
Author(s):  
Yeon-Ho Lee ◽  
Youn-Jea Kim
Keyword(s):  
Gas Turbine ◽  
Turbine Blade ◽  
Film Cooling ◽  
Working Fluid ◽  
Fluid Temperature ◽  
Cooling Efficiency ◽  
Gas Turbine Blade ◽  
Cooling Performance ◽  
Cooling Tube ◽  
Film Cooling Efficiency

A high working fluid temperature in a gas turbine is required to improve its efficiency. However, high temperatures also reduce turbine blade durability. Film-cooling is one blade cooling method to control gas turbine blade temperature. In this study, film cooling performance was numerically investigated with various configurations of a groove patterned cooling tube. The CO2 blowing ratio of the cooling fluid was varied from 0.6 to 1.4 with 0.2 intervals. The numerical analysis was conducted using the ANSYS CFX ver. 16.1 commercial code. The film cooling efficiency and pressure distribution were graphically depicted and analyzed to derive the groove configuration with the highest film cooling efficiency. In particular, the flow field on the turbine blade with the circular groove configuration showed more uniform distribution compared to the reference model.

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.

Film Cooling and Aerodynamic Performance on Multi-Cavity Squealer Tip of a Turbine Blade

2021 ◽  
Author(s):  
Feng Li ◽  
Zhao Liu ◽  
Zhenping Feng
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Pressure Loss ◽  
Total Pressure ◽  
Aerodynamic Performance ◽  
Total Pressure Loss ◽  
Cooling Performance ◽  
Pressure Loss Coefficient ◽  
Blade Tip ◽  
Total Pressure Loss Coefficient

Abstract The blade tip region of the shroud-less high-pressure gas turbine is exposed to an extremely operating condition with combined high temperature and high heat transfer coefficient. It is critical to design new tip structures and apply effective cooling method to protect the blade tip. Multi-cavity squealer tip has the potential to reduce the huge thermal loads and improve the aerodynamic performance of the blade tip region. In this paper, numerical simulations were performed to predict the aerothermal performance of the multi-cavity squealer tip in a heavy-duty gas turbine cascade. Different turbulence models were validated by comparing to the experimental data. It was found that results predicted by the shear-stress transport with the γ-Reθ transition model have the best precision. Then, the film cooling performance, the flow field in the tip gap and the leakage losses were presented with several different multi-cavity squealer tip structures, under various coolant to mainstream mass flow ratios (MFR) from 0.05% to 0.15%. The results show that the ribs in the multi-cavity squealer tip could change the flow structure in the tip gap for that they would block the coolant and the leakage flow. In this study, the case with one-cavity (1C) achieves the best film cooling performance under a lower MFR. However, the cases with multi-cavity (2C, 3C, 4C) show higher film cooling effectiveness under a higher MFR of 0.15%, which are 32.6%%, 34.2%% and 41.0% higher than that of the 1C case. For the aerodynamic performance, the case with single-cavity has the largest total pressure loss coefficient in all MFR studied, whereas the case with two-cavity obtains the smallest total pressure loss coefficient, which is 7.6% lower than that of the 1C case.

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.

A CFD-Based Parametric Study on Modification of Discrete Sister Holes Location for the Film Cooling Flow

2014 ◽  
Author(s):  
Siavash Khajehhasani ◽  
Bassam Jubran
Keyword(s):  
Film Cooling ◽  
Numerical Study ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Base Case ◽  
Spanwise Direction ◽  
Cooling Performance ◽  
Cooling Flow ◽  
Lift Off ◽  
The Individual

A numerical study on the effects of sister holes locations on film cooling performance is presented. This includes the change of the location of the individual discrete sister holes in the streamwise and spanwise directions, where each one of these directions includes 9 different locations, 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 variation of the sister holes in the streamwise direction provides similar film cooling performance as the base case for both blowing ratios of 0.5 and 1. On the other hand, the spanwise variation of the sister holes’ location has a more prominent effect on the effectiveness. In some cases, as a result of the anti-vortices generated from the sister holes and the repositioning of the sister holes in the spanwise direction, the jet lift-off effect notably decreases and more volume of coolant is distributed in the spanwise direction.

Exploring Conjugate CFD Heat Transfer Characteristics for a Film-Cooled Flat Plate and 3-D Turbine Inlet Vane

2012 ◽  
Author(s):  
J. J. Johnson ◽  
P. I. King ◽  
J. P. Clark ◽  
P. J. Koch
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Film Cooling ◽  
Low Cost ◽  
Full Scale ◽  
Design Flow ◽  
Navier Stokes ◽  
Cooling Performance ◽  
Cooling Design ◽  
Computational Fluid Dynamics Cfd

As part of a thorough benchmarking of the baseline cooling design in planned optimization work, Reynolds-Averaged Navier Stokes (RANS) conjugate heat transfer (CHT) computational fluid dynamics (CFD) assessments have been accomplished at RTV design flow conditions to simulate both a cooled flat plate pressure side (PS) model infrared thermography experiment as well as a full-scale, fully-cooled, full-wheel blowdown experiment on the same high pressure turbine (HPT) vane. Numerous past works on turbomachinery film cooling have been conducted using flat plate models because of their simplicity, repeatability, and low cost of experimentation relative to full scale rotating blowdown rigs. Some of these works generated film cooling correlations still in use today in industry for HPT components. The CFD assessments in this work provide insight into the fundamental differences between a flat plate model and a realistic 3-D vane in terms of film cooling performance for the same PS cooling array. The comparisons of results wring out expected differences between the geometries due to aspects such as highly curved surfaces and endwall effects. However, with nearly-matched coolant-to-mainstream temperature and pressure ratios, the cooling performance between the two models is surprisingly similar, especially in the midspan region. The similarities and differences observed herein represent the rigor and accuracy afforded by simulating both the solid and fluid domains as well as the high-density unstructured meshes that take into account all individual cooling passages and internal plenums, on top of the typically-assessed external fluid flow field.

Film Cooling Effectiveness for Short Film Cooling Holes Fed by a Narrow Plenum

1999 ◽  
Vol 122 (3) ◽  
pp. 553-557 ◽  
Author(s):  
C. A. Hale ◽  
M. W. Plesniak ◽  
S. Ramadhyani
Keyword(s):  
Film Cooling ◽  
Short Film ◽  
Injection Hole ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Single Row ◽  
Hole Geometry ◽  
Thin Walled ◽  
Film Cooling Holes

The adiabatic, steady-state liquid crystal technique was used to measure surface adiabatic film cooling effectiveness values in the near-hole region X/D<10. A parametric study was conducted for a single row of short holes L/D⩽3 fed by a narrow plenum H/D=1. Film cooling effectiveness values are presented and compared for various L/D ratios (0.66 to 3.0), three different blowing ratios (0.5, 1.0, and 1.5), two different plenum feed configurations (co-flow and counterflow), and two different injection angles (35 and 90 deg). Injection hole geometry and plenum feed direction were found to affect short hole film cooling performance significantly. Under certain conditions, similar or improved coverage was achieved with 90 deg holes compared with 35 deg holes. This result has important implications for manufacturing of thin-walled film-cooled blades or vanes. [S0889-504X(00)00603-6]

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