Effect of Internal Crossflow on Double Jet Film Cooling Holes of Helium Turbine Blades

2017 ◽  
Author(s):  
Xiao-kai Sun ◽  
Wei Peng ◽  
Jie Wang ◽  
Pei-xue Jiang
Keyword(s):  
High Temperature ◽  
Flow Rate ◽  
Film Cooling ◽  
Turbine Blades ◽  
High Flow ◽  
Cooling Efficiency ◽  
Cooling Performance ◽  
Supply Condition ◽  
Film Cooling Holes ◽  
Very High

In the present study, effect of internal crossflow on double jet film cooling holes were investigated. In our previous study, four types of film cooling holes was investigated and the double jet holes showed better cooling efficiency. However, in practice, the coolant in high temperature turbine blade has a very high flow rate and turbulence, so it is necessary to take the effect of coolant supply condition at the hole entrance into consideration. So the influence of coolant supply condition was investigated, the plenum condition and the crossflow condition were studied to show the influence of the coolant supply condition. And the cylindrical hole was also investigated as comparison. The results showed that there is a profound effect of how the coolant is supplied to the hole on the film-cooling performance in the near hole region. Therefore, crossflow at the hole entry side has be taken into account when modeling film-cooling.

IMPROVING THE FILM COOLING PERFORMANCE OF A TURBINE ENDWALL WITH MULTI-FIDELITY MODELING CONSIDERING CONJUGATE HEAT TRANSFER

2021 ◽  
pp. 1-20
Author(s):  
Hongyan Bu ◽  
Yufeng Yang ◽  
Liming Song ◽  
Jun Li
Keyword(s):  
Heat Transfer ◽  
Design Optimization ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Inlet Temperature ◽  
High Fidelity ◽  
Cooling Performance ◽  
Fine Mesh ◽  
Film Cooling Holes ◽  
Component Temperature

Abstract The gas turbine endwall is bearing extreme thermal loads with the rapid increase of turbine inlet temperature. Therefore, the effective cooling of turbine endwalls is of vital importance for the safe operation of turbines. In the design of endwall cooling layouts, numerical simulations based on conjugate heat transfer (CHT) are drawing more attention as the component temperature can be predicted directly. However, the computation cost of high-fidelity CHT analysis can be high and even prohibitive especially when there are many cases to evaluate such as in the design optimization of cooling layout. In this study, we established a multi-fidelity framework in which the data of low-fidelity CHT analysis was incorporated to help the building of a model that predicts the result of high-fidelity simulation. Based upon this framework, multi-fidelity design optimization of a validated numerical turbine endwall model was carried out. The high and low fidelity data were obtained from the computation of fine mesh and coarse mesh respectively. In the optimization, the positions of the film cooling holes were parameterized and controlled by a shape function. With the help of multi-fidelity modeling and sequentially evaluated designs, the cooling performance of the model endwall was improved efficiently.

scholarly journals Albian drilling's and its hydropower potential in Algeria: Study and exploitation

2018 ◽  
Vol 38 (1) ◽  
pp. 8-15
Author(s):  
Salim Etsouri ◽  
Ferhat Kaci ◽  
Mohamed Bouaziz
Keyword(s):  
Sustainable Development ◽  
Flow Rate ◽  
Underground Water ◽  
High Flow ◽  
Aquifer System ◽  
Output Pressure ◽  
Turbo Generator ◽  
Hydropower Potential ◽  
Long Time ◽  
Very High

The Continental intercalary groundwater is highly sought for its water as resources hugely mobilized in Northern Sahara. A very high flow rate and output pressure characterizes this underground water. It amounts from 50 to 400 l.s-1 for the flow, and from 5 to 40 bar for pressure. A survey of the Northern Sahara Aquifer System was essential to prove the existence of this potential. This energy appears into the artesian form, which remains very considerable for a very long time in most drilling. We have realised that this energy is immense, as well as the expanded volume of the groundwater, and the importance of its use in agriculture. Unfortunately, this potential remains untapped to this day and the energy of this water is completely neglected. Several turbo generator and/or inverted pump (PATs) integration tests were undergone. The new concept of reflection with respect to the environment and sustainable development has led us to structure our work towards the extension of this potential in order to extract the exploitable energy.

Rib Turbulator Effects on Crossflow-Fed Shaped Film Cooling Holes

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Dale W. Fox ◽  
Fraser B. Jones ◽  
John W. McClintic ◽  
David G. Bogard ◽  
Thomas E. Dyson ◽  
...  
Keyword(s):  
Film Cooling ◽  
Velocity Ratio ◽  
Cooling Effectiveness ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Smooth Channel ◽  
Cooling Hole ◽  
Film Cooling Holes ◽  
Inlet Position ◽  
The Impact

Most studies of turbine airfoil film cooling in laboratory test facilities have used relatively large plenums to feed flow into the coolant holes. However, a more realistic inlet condition for the film cooling holes is a relatively small channel. Previous studies have shown that the film cooling performance is significantly degraded when fed by perpendicular internal crossflow in a smooth channel. In this study, angled rib turbulators were installed in two geometric configurations inside the internal crossflow channel, at 45 deg and 135 deg, to assess the impact on film cooling effectiveness. Film cooling hole inlets were positioned in both prerib and postrib locations to test the effect of hole inlet position on film cooling performance. A test was performed independently varying channel velocity ratio and jet to mainstream velocity ratio. These results were compared to the film cooling performance of previously measured shaped holes fed by a smooth internal channel. The film cooling hole discharge coefficients and channel friction factors were also measured for both rib configurations with varying channel and inlet velocity ratios. Spatially averaged film cooling effectiveness is largely similar to the holes fed by the smooth internal crossflow channel, but hole-to-hole variation due to inlet position was observed.

scholarly journals Numerical Prediction of Film Cooling Effectiveness and the Associated Aerodynamic Losses With a Three-Dimensional Calculation Procedure

1990 ◽  
Author(s):  
G. H. Dibelius ◽  
R. Pitt ◽  
B. Wen
Keyword(s):  
Experimental Data ◽  
Film Cooling ◽  
Reverse Flow ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Temperature Pattern ◽  
Main Stream ◽  
Cooling Efficiency ◽  
Film Cooling Effectiveness ◽  
Aerodynamic Losses

Film cooling of turbine blades by injecting air through holes or slots affects the main stream flow. A numerical model has been developed to predict the resulting three-dimensional flow and the temperature pattern under steady flow conditions. An elliptic procedure is used in the near injection area to include reverse flow situations, while in the upstream area as well as far downstream a partial-parabolic procedure is applied. As first step an adiabatic wall has been assumed as boundary condition, since for this case experimental data are readily available for comparison. At elevated momentum blowing rates, zones of reverse flow occur downstream of the injection holes resulting in a decrease of cooling efficiency. A variation of the relevant parameters momentum blowing rate m, injection angle α and ratio of hole spacing to diameter s/d revealed the combination of m ≈ 1, α ≈ 30° and s/d ≈ 2 to be the optimum with respect to the averaged cooling efficiency and to the aerodynamic losses. Cooling is more efficient with slots than with a row of holes not considering the related problems of manufacture and service life. The calculated temperature patterns compare well with the experimental data available.

scholarly journals FEATURES OF ORGANIZATION OF FILM COOLING OF HIGH TEMPERATURE GAS TURBINES BLADES

2017 ◽  
Vol 39 (4) ◽  
pp. 11-20
Author(s):  
A. A. Khalatov ◽  
A. S. Kovalenko ◽  
S. B. Reznik
Keyword(s):  
High Temperature ◽  
Film Cooling ◽  
Gas Turbines ◽  
Small Dimension ◽  
Cooling Efficiency ◽  
Local Distribution ◽  
Cooling Air ◽  
High Temperature Gas

The features of the release of the cooling air in the interscapular channel high temperature gas turbines at the film cooling are considered. Possibilities of its local distribution on contour of an entrance edge of the perforated blades are investigated. The presented calculations show that the substantial increase in the cooling efficiency can be attained due to channels of small dimension in the blade wall.  

Improving the Film Cooling Performance of a Turbine Endwall With Multi-Fidelity Modeling Considering Conjugate Heat Transfer

2021 ◽  
Author(s):  
Hongyan Bu ◽  
Yufeng Yang ◽  
Liming Song ◽  
Jun Li
Keyword(s):  
Heat Transfer ◽  
Design Optimization ◽  
Film Cooling ◽  
Conjugate Heat Transfer ◽  
Inlet Temperature ◽  
High Fidelity ◽  
Cooling Performance ◽  
Fine Mesh ◽  
Film Cooling Holes ◽  
Component Temperature

Abstract The gas turbine endwall is bearing extreme thermal loads with the rapid increase of turbine inlet temperature. Therefore, the effective cooling of turbine endwalls is of vital importance for the safe operation of turbines. In the design of endwall cooling layouts, numerical simulations based on conjugate heat transfer (CHT) are drawing more attention as the component temperature can be predicted directly. However, the computation cost of high-fidelity CHT analysis can be high and even prohibitive especially when there are many cases to evaluate such as in the design optimization of cooling layout. In this study, we established a multi-fidelity framework in which the data of low-fidelity CHT analysis was incorporated to help the building of a model that predicts the result of high-fidelity simulation. Based upon this framework, multi-fidelity design optimization of a validated numerical turbine endwall model was carried out. The high and low fidelity data were obtained from the computation of fine mesh and coarse mesh respectively. In the optimization, the positions of the film cooling holes were parameterized and controlled by a shape function. With the help of multi-fidelity modeling and sequentially evaluated designs, the cooling performance of the model endwall was improved efficiently.

Heat Transfer Coefficient Measurements of Film-Cooling Holes With Expanded Exits

1998 ◽  
Author(s):  
M. Gritsch ◽  
A. Schulz ◽  
S. Wittig
Keyword(s):  
Heat Transfer ◽  
Mach Number ◽  
Film Cooling ◽  
Cylindrical Hole ◽  
Superposition Method ◽  
Transfer Coefficients ◽  
Cooling Performance ◽  
Heat Transfer Coefficients ◽  
Film Cooling Holes ◽  
Injection Location

Detailed measurements of heat transfer coefficients in the nearfield of three different film-cooling holes are presented. The hole geometries investigated include a cylindrical hole and two holes with a diffuser shaped exit portion (i.e. a fan-shaped and a laidback fanshaped hole). They were tested over a range of blowing ratios M = 0.25…1.75 at an external crossflow Mach number of 0.6 and a coolant-to-mainflow density ratio of 1.85. Additionally, the effect of the internal coolant supply Mach number is addressed. Temperatures of the diabatic surface downstream of the injection location are measured by means of an infrared camera system. They are used as boundary conditions for a finite element analysis to determine surface heat fluxes and heat transfer coefficients. The superposition method is applied to evaluate the overall film-cooling performance of the hole geometries investigated. As compared to the cylindrical hole, both expanded holes show significantly lower heat transfer coefficients downstream of the injection location, particularly at high blowing ratios. The laidback fanshaped hole provides a better lateral spreading of the injected coolant than the fanshaped hole which leads to lower laterally averaged heat transfer coefficients. Coolant passage crossflow Mach number affects the flowfield of the jet being ejected from the hole and, therefore, has an important impact on film-cooling performance.

Numerical Approach at Flat Plate for Predicting the Film Cooling Effectiveness Part A: Effect Blowing Ratio

2018 ◽  
Vol 16 ◽  
pp. 30-44 ◽  
Author(s):  
Farouk Kebir ◽  
Azzeddine Khorsi
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Film Cooling ◽  
Thermal Stresses ◽  
Free Stream ◽  
Turbine Blades ◽  
Cooling Performance ◽  
Film Cooling Effectiveness ◽  
Free Stream Turbulence ◽  
Blowing Ratio

Film cooling is vital for gas turbine blades to protect them from thermal stresses and high temperatures due to the hot gas flow in the blade surface. Film cooling is applied to almost all external surfaces associated with aerodynamic profiles that are exposed to hot combustion gases such as main bodies, end-walls, blade tips and leading edges. In a review of the literature, it was found that there are strong effects of free-stream turbulence, surface curvature and hole shape on film cooling performance also blowing ratio. The performance of the film cooling is difficult to predict due to the inherent complex flow fields along the surfaces of the airfoil components in the turbine engines. From all what we introducing the film cooling is reviewed through a discussion of the analyses methodologies, a physical description, and the various influences on film-cooling performance. Initially Computational analysis was done on a flat plate with hole inclined at 55° to the surface plate. This study focuses on the efficient computation of film cooling flows with three blowing ratio. The numerical results show the effectiveness cooling and heat transfer behavior with increasing injection blowing ratio M (0.5, 1, and 1.5). The influence of increased blade film cooling can be assessed via the values of Nusselt number in terms of reduced heat transfer to the blade. Predictions of film effectiveness are compared with experimental results for a circular jet at blowing ratios ranging from 0.5, 1.0 and 1.5. The present results are obtained at a free stream turbulence of 10%, which are the typical conditions upstream of the effectiveness is generally lower for a large stream-wise angle of 55°.

Design of Full-Scale Endwall Film Cooling of a Turbine Vane

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Jian Liu ◽  
Wei Du ◽  
Guohua Zhang ◽  
Safeer Hussain ◽  
Lei Wang ◽  
...  
Keyword(s):  
High Temperature ◽  
Film Cooling ◽  
Pressure Coefficient ◽  
Pressure Side ◽  
Junction Region ◽  
Film Cooling Effectiveness ◽  
Coefficient Distribution ◽  
Turbine Vane ◽  
Endwall Film Cooling ◽  
Film Cooling Holes

Abstract Endwall film cooling is a significant cooling method to protect the endwall region and the junction region of endwall and a turbine vane, where usually a relatively high temperature load exists. This work aims to find the optimized arrangement of film cooling holes on the endwall and improve the film cooling in some difficult regions on the endwall, such as pressure side-endwall junction region. Several ideas for film cooling hole arrangement design are proposed, based on the pressure coefficient distribution, the streamline distribution, and the heat transfer coefficient (HTC) distribution, respectively. Four specified designs are built and compared. The results are obtained by numerical calculations with a well-validated turbulence model, the k–ω shear stress transport (SST) model. From this work, the designs based on the pressure coefficient distribution (designs 1 and 2) force the flow from the pressure side to the suction side (SS), especially in design 2, which adopts compound angle holes. The designs based on pressure coefficients have benefit in the cooling of the SS but give worse coolant coverage on the pressure side. In addition, designs 1 and 2 have little influence on the original pressure field. The design based on the streamline distributions (design 3) has larger coolant coverage on the endwall and provides good coolant coverage on the endwall and pressure side junction region. The design based on the HTC distribution provides large overall film cooling effectiveness on both the pressure side and the SS. More film cooling holes are placed on the high temperature regions, which is more effective in practice.

Experimental Study on Geometric Precision of Microholes Drilling by Picosecond Laser

2019 ◽  
Author(s):  
Zhanfei Zhang ◽  
Wenhu Wang ◽  
Ruisong Jiang ◽  
Chengcheng Jin ◽  
Xiaoxiang Zhu ◽  
...  
Keyword(s):  
Film Cooling ◽  
Three Dimensional ◽  
Great Influence ◽  
Picosecond Laser ◽  
Scanning Speed ◽  
Cooling Efficiency ◽  
Measuring Instrument ◽  
Geometric Precision ◽  
Cooling Hole ◽  
Film Cooling Holes

Abstract The geometric precision of the film cooling hole has a great influence on the cooling efficiency and fatigue life of the turbine blade. In the paper, the processing of film cooling holes on DD6 single crystal superalloy by picosecond laser is investigated. The pulse laser at pulse duration of 2.1ps, the wavelength of 1030 nm and the repetition frequency of 75 kHz are selected to study the pulse energy, scanning speed, defocus and scanning width on the geometric precision of the film cooling hole. After drilling, the three-dimensional coordinates of the entrance and exit plane of the film cooling holes are obtained by using the three-dimensional surface measuring instrument. The diameter, roundness and taper of the film cooling holes are calculated by extracting and processing the coordinate points of the contour around the microholes. The experimental results show that defocusing has the greatest influence on the taper and roundness of film cooling holes. Negative defocusing can produce severe plasma shielding, which makes the exit roundness and taper larger. With larger pulses, positive defocusing and larger scanning width, smaller roundness and taper can be produced.

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