Investigations Of Flow And Film Cooling On Turbine Blade Edge Regions

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Investigations of Flow and Film Cooling on Turbine Blade Edge Regions

Author : Huitao Yang
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (1 download)

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Book Synopsis Investigations of Flow and Film Cooling on Turbine Blade Edge Regions by : Huitao Yang

Download or read book Investigations of Flow and Film Cooling on Turbine Blade Edge Regions written by Huitao Yang and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The inlet temperature of modern gas turbine engines has been increased to achieve higher thermal efficiency and increased output. The blade edge regions, including the blade tip, the leading edge, and the platform, are exposed to the most extreme heat loads, and therefore, must be adequately cooled to maintain safety. For the blade tip, there is tip leakage flow due to the pressure gradient across the tip. This leakage flow not only reduces the blade aerodynamic performance, but also yields a high heat load due to the thin boundary layer and high speed. Various tip configurations, such as plane tip, double side squealer tip, and single suction side squealer tip, have been studied to find which one is the best configuration to reduce the tip leakage flow and the heat load. In addition to the flow and heat transfer on the blade tip, film cooling with various arrangements, including camber line, upstream, and two row configurations, have been studied. Besides these cases of low inlet/outlet pressure ratio, low temperature, non-rotating, the high inlet/outlet pressure ratio, high temperature, and rotating cases have been investigated, since they are closer to real turbine working conditions. The leading edge of the rotor blade experiences high heat transfer because of the stagnation flow. Film cooling on the rotor leading edge in a 11/2 turbine stage has been numerically studied for the designand off-design conditions. Simulations find that the increasing rotating speed shifts the stagnation line from the pressure side, to the leading edge and the suction side, while film cooling protection moves in the reverse direction with decreasing cooling effectiveness. Film cooling brings a high unsteady intensity of the heat transfer coefficient, especially on the suction side. The unsteady intensity of film cooling effectiveness is higher than that of the heat transfer coefficient. The film cooling on the rotor platform has gained significant attention due to the usage of low-aspect ratio and low-solidity turbine designs. Film cooling and its heat transfer are strongly influenced by the secondary flow of the end-wall and the stator-rotor interaction. Numerical predictions have been performed for the film cooling on the rotating platform of a whole turbine stage. The design conditions yield a high cooling effectiveness and decrease the cooling effectiveness unsteady intensity, while the high rpm condition dramatically reduces the film cooling effectiveness. High purge flow rates provide a better cooling protection. In addition, the impact of the turbine work process on film cooling effectiveness and heat transfer coefficient has been investigated. The overall cooling effectiveness shows a higher value than the adiabatic effectiveness does.

Survey of Advantages and Problems Associated with Transpiration Cooling and Film Cooling of Gas-turbine Blades

Author : Ernst Rudolf Georg Eckert
Publisher :
ISBN 13 :
Total Pages : 44 pages
Book Rating : 4.3/5 (126 download)

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Book Synopsis Survey of Advantages and Problems Associated with Transpiration Cooling and Film Cooling of Gas-turbine Blades by : Ernst Rudolf Georg Eckert

Download or read book Survey of Advantages and Problems Associated with Transpiration Cooling and Film Cooling of Gas-turbine Blades written by Ernst Rudolf Georg Eckert and published by . This book was released on 1951 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Summary: Transpiration and film cooling promise to be effective methods of cooling gas-turbine blades; consequently, analytical and experimental investigations are being conducted to obtain a better understanding of these processes. This report serves as an introduction to these cooling methods, explains the physical processes, and surveys the information available for predicting blade temperatures and heat-transfer rates. In addition, the difficulties encountered in obtaining a uniform blade temperature are discussed, and the possibilities of correcting these difficulties are indicated. Air is the only coolant considered in the application of these cooling methods.

Heat Transfer in Gas Turbines

Author : Bengt Sundén
Publisher : Witpress
ISBN 13 :
Total Pages : 544 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Heat Transfer in Gas Turbines by : Bengt Sundén

Download or read book Heat Transfer in Gas Turbines written by Bengt Sundén and published by Witpress. This book was released on 2001 with total page 544 pages. Available in PDF, EPUB and Kindle. Book excerpt: This title presents and reflects current active research on various heat transfer topics and related phenomena in gas turbine systems. It begins with a general introduction to gas turbine heat transfer, before moving on to specific areas.

Experimental Investigation of Film Cooling Effectiveness on Gas Turbine Blades

Author : Zhihong Gao
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (69 download)

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Book Synopsis Experimental Investigation of Film Cooling Effectiveness on Gas Turbine Blades by : Zhihong Gao

Download or read book Experimental Investigation of Film Cooling Effectiveness on Gas Turbine Blades written by Zhihong Gao and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The hot gas temperature in gas turbine engines is far above the permissible metal temperatures. Advanced cooling technologies must be applied to cool the blades, so they can withstand the extreme conditions. Film cooling is widely used in modern high temperature and high pressure blades as an active cooling scheme. In this study, the film cooling effectiveness in different regions of gas turbine blades was investigated with various film hole/slot configurations and mainstream flow conditions. The study consisted of four parts: 1) effect of upstream wake on blade surface film cooling, 2) effect of upstream vortex on platform purge flow cooling, 3) influence of hole shape and angle on leading edge film cooling and 4) slot film cooling on trailing edge. Pressure sensitive paint (PSP) technique was used to get the conduction-free film cooling effectiveness distribution. For the blade surface film cooling, the effectiveness from axial shaped holes and compound angle shaped holes were examined. Results showed that the compound angle shaped holes offer better film effectiveness than the axial shaped holes. The upstream stationary wakes have detrimental effect on film effectiveness in certain wake rod phase positions. For platform purge flow cooling, the stator-rotor gap was simulated by a typical labyrinth-like seal. Delta wings were used to generate vortex and modeled the passage vortex generated by the upstream vanes. Results showed that the upstream vortex reduces the film cooling effectiveness on the platform. For the leading edge film cooling, two film cooling designs, each with four film cooling hole configurations, were investigated. Results showed that the shaped holes provide higher film cooling effectiveness than the cylindrical holes at higher average blowing ratios. In the same range of average blowing ratio, the radial angle holes produce better effectiveness than the compound angle holes. The seven-row design results in much higher effectiveness than the three-row design. For the trailing edge slot cooling, the effect of slot lip thickness on film effectiveness under the two mainstream conditions was investigated. Results showed thinner lips offer higher effectiveness. The film effectiveness on the slots reduces when the incoming mainstream boundary layer thickness decreases.

Experimental Investigation of Air-cooled Turbine Blades in Turbojet Engine

Author : Vernon L. Arne
Publisher :
ISBN 13 :
Total Pages : 56 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Experimental Investigation of Air-cooled Turbine Blades in Turbojet Engine by : Vernon L. Arne

Download or read book Experimental Investigation of Air-cooled Turbine Blades in Turbojet Engine written by Vernon L. Arne and published by . This book was released on 1951 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Gas Turbine Blade Cooling

Author : Chaitanya D Ghodke
Publisher : SAE International
ISBN 13 : 0768095026
Total Pages : 238 pages
Book Rating : 4.7/5 (68 download)

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Book Synopsis Gas Turbine Blade Cooling by : Chaitanya D Ghodke

Download or read book Gas Turbine Blade Cooling written by Chaitanya D Ghodke and published by SAE International. This book was released on 2018-12-10 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gas turbines play an extremely important role in fulfilling a variety of power needs and are mainly used for power generation and propulsion applications. The performance and efficiency of gas turbine engines are to a large extent dependent on turbine rotor inlet temperatures: typically, the hotter the better. In gas turbines, the combustion temperature and the fuel efficiency are limited by the heat transfer properties of the turbine blades. However, in pushing the limits of hot gas temperatures while preventing the melting of blade components in high-pressure turbines, the use of effective cooling technologies is critical. Increasing the turbine inlet temperature also increases heat transferred to the turbine blade, and it is possible that the operating temperature could reach far above permissible metal temperature. In such cases, insufficient cooling of turbine blades results in excessive thermal stress on the blades causing premature blade failure. This may bring hazards to the engine's safe operation. Gas Turbine Blade Cooling, edited by Dr. Chaitanya D. Ghodke, offers 10 handpicked SAE International's technical papers, which identify key aspects of turbine blade cooling and help readers understand how this process can improve the performance of turbine hardware.

Gas Turbine Heat Transfer and Cooling Technology, Second Edition

Author : Je-Chin Han
Publisher : CRC Press
ISBN 13 : 1439855684
Total Pages : 892 pages
Book Rating : 4.4/5 (398 download)

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Book Synopsis Gas Turbine Heat Transfer and Cooling Technology, Second Edition by : Je-Chin Han

Download or read book Gas Turbine Heat Transfer and Cooling Technology, Second Edition written by Je-Chin Han and published by CRC Press. This book was released on 2012-11-27 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive reference for engineers and researchers, Gas Turbine Heat Transfer and Cooling Technology, Second Edition has been completely revised and updated to reflect advances in the field made during the past ten years. The second edition retains the format that made the first edition so popular and adds new information mainly based on selected published papers in the open literature. See What’s New in the Second Edition: State-of-the-art cooling technologies such as advanced turbine blade film cooling and internal cooling Modern experimental methods for gas turbine heat transfer and cooling research Advanced computational models for gas turbine heat transfer and cooling performance predictions Suggestions for future research in this critical technology The book discusses the need for turbine cooling, gas turbine heat-transfer problems, and cooling methodology and covers turbine rotor and stator heat-transfer issues, including endwall and blade tip regions under engine conditions, as well as under simulated engine conditions. It then examines turbine rotor and stator blade film cooling and discusses the unsteady high free-stream turbulence effect on simulated cascade airfoils. From here, the book explores impingement cooling, rib-turbulent cooling, pin-fin cooling, and compound and new cooling techniques. It also highlights the effect of rotation on rotor coolant passage heat transfer. Coverage of experimental methods includes heat-transfer and mass-transfer techniques, liquid crystal thermography, optical techniques, as well as flow and thermal measurement techniques. The book concludes with discussions of governing equations and turbulence models and their applications for predicting turbine blade heat transfer and film cooling, and turbine blade internal cooling.

Experimental Investigation of Air-cooled Turbine Blades in Turbojet Engine

Author : Herman H. Ellerbrock (Jr.)
Publisher :
ISBN 13 :
Total Pages : 78 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Experimental Investigation of Air-cooled Turbine Blades in Turbojet Engine by : Herman H. Ellerbrock (Jr.)

Download or read book Experimental Investigation of Air-cooled Turbine Blades in Turbojet Engine written by Herman H. Ellerbrock (Jr.) and published by . This book was released on 1951 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Systematic Study of Shaped-hole Film Cooling at the Leading Edge of a Scaled-up Turbine Blade

Author : Jacob Damian Moore
Publisher :
ISBN 13 :
Total Pages : 484 pages
Book Rating : 4.:/5 (124 download)

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Book Synopsis Systematic Study of Shaped-hole Film Cooling at the Leading Edge of a Scaled-up Turbine Blade by : Jacob Damian Moore

Download or read book Systematic Study of Shaped-hole Film Cooling at the Leading Edge of a Scaled-up Turbine Blade written by Jacob Damian Moore and published by . This book was released on 2020 with total page 484 pages. Available in PDF, EPUB and Kindle. Book excerpt: The leading-edge regions of turbine vanes and blades require careful attention to their cooling designs because of the high heat loads. External cooling is typically accomplished with dense "showerhead" arrangements of film cooling holes surrounding the stagnation point at the airfoil leading edge. In modern film cooling studies, shaped holes are prevalent in downstream areas of turbine airfoils; however, the literature contains few studies of shaped holes in the showerhead. This leads to a lack of physics-based insight that would lead to the design of high-performing showerhead arrays. This study examined the performance and physical behavior of several showerhead arrangements at the leading edge of a scaled-up turbine blade. A low-speed linear cascade test section was used to simulate the blade environment, and experiments were conducted at scaled engine-realistic conditions. First, the cooling performances of baseline cylindrical and shaped hole designs were compared. The shaped hole design mimicked a standard design in the literature for flat plate studies but with some modifications expected to improve performance specifically at the leading edge. The result was a novel off-center, elliptically-expanding hole. Adiabatic effectiveness and thermal field measurements revealed that the baseline shaped hole had 20-100% performance due to better jet attachment, stemming from its diffuser, which effectively decreased the exit momenta of the coolant jets. The expansion area ratio was increased by 40% for a subsequent design to gauge sensitivity to this parameter; but, surprisingly, the performances of the new design and of the baseline one were nearly identical. A third shaped hole design with a 45% larger breakout area but an identical expansion area resulted in slightly worse performance than either, highlighting the detrimental effect of increasing breakout area and expansion angle. These experiments informed a new proposed scaling parameter incorporating both of these areas and their counteracting effects to predict shaped hole performance in the showerhead. The highest performing design of the group was then tested with an engine-realistic impingement coolant feed, for which performance was overall similar. Supplemental thermal fields using this configuration were performed to construct a 3D representation of the flow field in the showerhead region

Impingement Jet Cooling in Gas Turbines

Author : R.S. Amano
Publisher : WIT Press
ISBN 13 : 1845649060
Total Pages : 253 pages
Book Rating : 4.8/5 (456 download)

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Book Synopsis Impingement Jet Cooling in Gas Turbines by : R.S. Amano

Download or read book Impingement Jet Cooling in Gas Turbines written by R.S. Amano and published by WIT Press. This book was released on 2014-05-28 with total page 253 pages. Available in PDF, EPUB and Kindle. Book excerpt: Due to the requirement for enhanced cooling technologies on modern gas turbine engines, advanced research and development has had to take place in field of thermal engineering. Among the gas turbine cooling technologies, impingement jet cooling is one of the most effective in terms of cooling effectiveness, manufacturability and cost. The chapters contained in this book describe research on state-of-the-art and advanced cooling technologies that have been developed, or that are being researched, with a variety of approaches from theoretical, experimental, and CFD studies. The authors of the chapters have been selected from some of the most active researchers and scientists on the subject. This is the first to book published on the topics of gas turbines and heat transfer to focus on impingement cooling alone.

Parametric Study of Gas Turbine Film-cooling

Author : Kevin Liu
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (818 download)

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Book Synopsis Parametric Study of Gas Turbine Film-cooling by : Kevin Liu

Download or read book Parametric Study of Gas Turbine Film-cooling written by Kevin Liu and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this study, the film-cooling effectiveness in different regions of gas turbine blades was investigated with various film hole/slot configurations and mainstream flow conditions. The study consisted of three parts: 1) turbine blade span film-cooling, 2) turbine platform film-cooling, and 3) blade tip film-cooling. Pressure sensitive paint (PSP) technique was used to get the conduction-free film-cooling effectiveness distribution. Film-cooling effectiveness is assessed in terms of cooling hole geometry, blowing ratio, freestream turbulence, and coolant-to-mainstream density ratio. Blade span film-cooling test shows that the compound angle shaped holes offer better film effectiveness than the axial shaped holes. Greater coolant-to-mainstream density ratio prevents coolant to lift-off. Higher freestream turbulence causes effectiveness to drop everywhere except in the region downstream of suction side. Results are also correlated with momentum flux, compound shaped hole has the greatest optimum momentum flux ratio, and then followed by axial shaped hole, compound cylindrical hole, and axial cylindrical hole. For platform purge flow cooling, the stator-rotor gap was simulated by a typical labyrinth-like seal. Two different film-cooling hole geometries, three blowing ratios and density ratios, and two freestream turbulence are examined. Results showed that the shaped holes present higher film-cooling effectiveness and wider film coverage than the cylindrical holes, particularly at higher blowing ratios. Moreover, the platform film-cooling effectiveness increases with density ratio but decreases with turbulence intensity. The blade tip study was performed in a blow-down flow loop. Results show that a blowing ratio of 2.0 is found to give best results on the tip floor. Lift-off of the coolant jet can be observed for the holes closer to the leading edge as blowing ratio increases from 1.5 to 2.0. A stator vane suction side heat transfer study was conducted in a partial annular cascade. The heat transfer coefficients were measured by using the transient liquid crystal technique. At X/L=0.15, a low heat transfer region where transition occurs. The heat transfer coefficients increase toward the trailing edge as flow accelerates; a spanwise variation can be found at neat tip and hub portions due to passage and horseshoe vortices.

Three-dimensional Numerical Simulation of Film Cooling on a Turbine Blade Leading-edge Model

Author : Douglas Stenger
Publisher :
ISBN 13 :
Total Pages : 98 pages
Book Rating : 4.:/5 (319 download)

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Book Synopsis Three-dimensional Numerical Simulation of Film Cooling on a Turbine Blade Leading-edge Model by : Douglas Stenger

Download or read book Three-dimensional Numerical Simulation of Film Cooling on a Turbine Blade Leading-edge Model written by Douglas Stenger and published by . This book was released on 2009 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present study is a three-dimensional numerical investigation of the effectiveness of film cooling for a turbine blade leading-edge model with both a single and a three-hole cooling configuration. The model used has the same dimensions as those in the experimental investigation of Ou and Rivir (2006). It consists of a half cylinder with a flat after-body, and well represents the leading edge of a turbine blade. The single coolant hole is situated approximately at the spanwise center of the cylindrical model, and makes an angle of 21.5 degrees to the leading edge and 20 degrees to the spanwise direction. For the three-hole configuration, the center hole is positioned the same as the single hole in the single-hole configuration, with the adjacent holes located at a spanwise distance of 37.4 mm on either side of the center hole. Multi-block grids were generated using GridGen, and the flows were simulated using the flow solver Fluent. A highly clustered structured C-grid was developed around the leading edge of the model. The outer unstructured-grid domain represents the wind tunnel as used in the experimental study of Ou and Rivir (2006), and the leading-edge model is located at the center of the domain. Simulations were carried out for blowing ratios, M, ranging from 0.75 to 2.0. Turbulence was represented using the k-? shear-stress transport (SST) model, and the flow was assumed to have a free-stream turbulence intensity of 0.75%. Two types of boundary conditions were used to represent the blade wall: an adiabatic surface, and a conductive surface. The adiabatic-wall results over-predicted the film-cooling effectiveness in the far downstream region for low blowing ratios. Also, in the vicinity of the cooling hole, an increase in blowing ratio resulted in higher film cooling effectiveness than observed in the experiments. It should be noted that the steady RANS-based turbulence model used under-predicts the interaction between the coolant and mainstream flow near the cooling-pipe exit. The conductive-wall results show a much closer agreement with experimental data for film effectiveness as compared to the adiabatic-wall predictions. Simulations were also performed with higher values of turbulence intensity at the cooling-hole inlet, and these predicted the coolant-mainstream interaction and the film-cooling effectiveness more accurately. Finally, a novel concept of pulsing the coolant flow was implemented so as to achieve film-cooling effectiveness equivalent to that with constant cooling, but with reduced overall coolant air, thereby enhancing turbine efficiency. Pulsed cooling with pulsing frequency PF = 5 and 10Hz, and duty cycle DC = 50%, shows the greatest cooling effects. The three-hole cooling results indicate that the 49 mm spanwise distance used for computing the spanwise-averaged values for film-cooling effectiveness accounts for all of the film-coolant spreading provided by the single hole. Also, the neighboring cooling holes contribute little film cooling to the 49 mm spanwise distance. The most significant new finding in this work is that the inclusion of wall conductance is the main factor responsible for reproducing the experimental data.

Experimental Investigation of Turbine Blade Platform Film Cooling and Rotational Effect on Trailing Edge Internal Cooling

Author : Lesley Mae Wright
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (69 download)

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Book Synopsis Experimental Investigation of Turbine Blade Platform Film Cooling and Rotational Effect on Trailing Edge Internal Cooling by : Lesley Mae Wright

Download or read book Experimental Investigation of Turbine Blade Platform Film Cooling and Rotational Effect on Trailing Edge Internal Cooling written by Lesley Mae Wright and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The present work has been an experimental investigation to evaluate the applicability of gas turbine cooling technology. With the temperature of the mainstream gas entering the turbine elevated above the melting temperature of the metal components, these components must be cooled, so they can withstand prolonged exposure to the mainstream gas. Both external and internal cooling techniques have been studied as a means to increase the life of turbine components. Detailed film cooling effectiveness distributions have been obtained on the turbine blade platform with a variety of cooling configurations. Because the newly developed pressure sensitive paint (PSP) technique has proven to be the most suitable technique for measuring the film effectiveness, it was applied to a variety of platform seal configurations and discrete film flows. From the measurements it was shown advanced seals provide more uniform protection through the passage with less potential for ingestion of the hot mainstream gases into the engine cavity. In addition to protecting the outer surface of the turbine components, via film cooling, heat can also be removed from the components internally. Because the turbine blades are rotating within the engine, it is important to consider the effect of rotation on the heat transfer enhancement within the airfoil cooling channels. Through this experimental investigation, the heat transfer enhancement has been measured in narrow, rectangular channels with various turbulators. The present experimental investigation has shown the turbulators, coupled with the rotation induced Coriolis and buoyancy forces, result in non-uniform levels of heat transfer enhancement in the cooling channels. Advanced turbulator configurations can be used to provide increased heat transfer enhancement. Although these designs result in increased frictional losses, the benefit of the heat transfer enhancement outweighs the frictional losses.

Experimental Investigation of the Heat-transfer Characteristics of an Air-cooled Sintered Porous Turbine Blade

Author : Louis J. Schafer (Jr.)
Publisher :
ISBN 13 :
Total Pages : 38 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Experimental Investigation of the Heat-transfer Characteristics of an Air-cooled Sintered Porous Turbine Blade by : Louis J. Schafer (Jr.)

Download or read book Experimental Investigation of the Heat-transfer Characteristics of an Air-cooled Sintered Porous Turbine Blade written by Louis J. Schafer (Jr.) and published by . This book was released on 1952 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Investigation of Heat Transfer and Fluid Flow in the Pocket Region of a Gas Turbine Engine and Cooling of a Turbine Blade

Author : Jian Liu
Publisher :
ISBN 13 : 9789178950386
Total Pages : 0 pages
Book Rating : 4.9/5 (53 download)

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Book Synopsis Investigation of Heat Transfer and Fluid Flow in the Pocket Region of a Gas Turbine Engine and Cooling of a Turbine Blade by : Jian Liu

Download or read book Investigation of Heat Transfer and Fluid Flow in the Pocket Region of a Gas Turbine Engine and Cooling of a Turbine Blade written by Jian Liu and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

An Experimental Investigation of Turbine Blade Heat Transfer and Turbine Blade Trailing Edge Cooling

Author : Jungho Choi
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (585 download)

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Book Synopsis An Experimental Investigation of Turbine Blade Heat Transfer and Turbine Blade Trailing Edge Cooling by : Jungho Choi

Download or read book An Experimental Investigation of Turbine Blade Heat Transfer and Turbine Blade Trailing Edge Cooling written by Jungho Choi and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This experimental study contains two points; part 1 - turbine blade heat transfer under low Reynolds number flow conditions, and part 2 - trailing edge cooling and heat transfer. The effect of unsteady wake and free stream turbulence on heat transfer and pressure coefficients of a turbine blade was investigated in low Reynolds number flows. The experiments were performed on a five blade linear cascade in a low speed wind tunnel. A spoked wheel type wake generator and two different turbulence grids were employed to generate different levels of the Strouhal number and turbulence intensity, respectively. The cascade inlet Reynolds number based on blade chord length was varied from 15,700 to 105,000, and the Strouhal number was varied from 0 to 2.96 by changing the rotating wake passing frequency (rod speed) and cascade inlet velocity. A thin foil thermocouple instrumented blade was used to determine the surface heat transfer coefficient. A Liquid crystal technique based on hue value detection was used to measure the heat transfer coefficient on a trailing edge film cooling model and internal model of a gas turbine blade. It was also used to determine the film effectiveness on the trailing edge. For the internal model, Reynolds numbers based on the hydraulic diameter of the exit slot and exit velocity were 5,000, 10,000, 20,000, and 30,000 and corresponding coolant-to-mainstream velocity ratios were 0.3, 0.6, 1.2, and 1.8 for the external models, respectively. The experiments were performed at two different designs and each design has several different models such as staggered / inline exit, straight / tapered entrance, and smooth / rib entrance. The compressed air was used in coolant air. A circular turbulence grid was employed to upstream in the wind tunnel and square ribs were employed in the inlet chamber to generate turbulence intensity externally and internally, respectively.

Experimental Investigation of Advanced Film Cooling Schemes for a Gas Turbine Blade

Author : Mohamed Gaber Ghorab
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (11 download)

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Book Synopsis Experimental Investigation of Advanced Film Cooling Schemes for a Gas Turbine Blade by : Mohamed Gaber Ghorab

Download or read book Experimental Investigation of Advanced Film Cooling Schemes for a Gas Turbine Blade written by Mohamed Gaber Ghorab and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced cooling techniques are essential for further improvement in the efficiency and the power output of gas turbines. Turbine inlet temperatures of 1900 K are typical of current gas turbines, and there is an interest in increasing the temperatures for the next generation of gas turbine engines. Over the past decades, significant effort has been devoted to increase the turbine efficiency and to develop effective cooling strategies to maintain the blade temperature below the melting point of the alloys used to construct the airfoils. As a result, various cooling strategies have been developed such as film, impingement, and muti-pass cooling for the blades, and evaporative cooling for the inlet air. In this work, a state-of-the-art thermal turbomachinery test rig was designed and constructed to investigate the film-cooling performance of advanced film cooling schemes over a flat plate. Designing and constructing mechanical parts, as well developing software codes (Labview and image processing) for transient film cooling measurement was the foremost part of the current experimental work. The thermochromic liquid crystal (TLC) technique was used to measure wall surface temperature. A circular film hole was used to validate the current experimental technique and methodology. The validation results showed that the current experimental technique and methodology were deemed reliable. Subsequently, the film cooling performance of the louver and new hybrid schemes were investigated, experimentally. The louver scheme was proposed by Pratt and Whitney Canada (PWC) to allow the cooling flow to pass through a bend and to encroach an airfoil material (impingement effect), then exit to the outer surface of the airfoil through a designed film hole. Immarigeon and Hassan (2006) then Zhang and Hassan (2006) numerically investigated the film cooling effectiveness performance of the louver scheme. The hybrid scheme was proposed in the current study, which includes two consecutive film hole configurations with interior bending. The cooling performances for the two advanced schemes have been analyzed experimentally over a flat plate across blowing ratios of 0.5, 1.0 and 1.5 at a density ratio of 0.94. The results showed that the louver and the hybrid schemes enhanced the local and the average film cooling performance in terms of film cooling effectiveness, and the net heat flux reductions are better than other published film hole configurations. In addition, both schemes provided an extensively wide spray of 'secondary flow over the outer surface, and thus enhanced the lateral film cooling performance over the downstream surface area. Moreover, the two schemes produced an average heat transfer coefficient ratio near unity at low and high blowing ratios. As a result, the louver and the hybrid schemes are expected to reduce the temperature of the outer surface of the gas turbine airfoil and to provide superior cooling performance, which increases airfoil lifetime. In addition, the adiabatic film cooling performance and flow characteristics for the hybrid scheme were investigated numerically. The numerical investigation was analyzed across blowing ratio, of 0.5, 1, and 2. The flow structures of the hybrid scheme are presented at different blowing ratios to provide a better physical understanding. The results showed that the hybrid scheme directed the secondary flow in the horizontal direction and reduced the jet liftoff at different blowing ratios. Finally, conjugate heat transfer (CHT) and film-cooling analyses were performed to investigate the hybrid scheme performance with different flow configurations. Different geometries of parallel flow and jet impingement with different gap heights as well as the adiabatic case study were investigated at blowing ratios of 0.5 and 1.0. The results showed that the adiabatic case provided downstream centerline superlative cooling performance near the hybrid film hole exit compared to other conjugate geometries studied. At the downstream location, the impingement configuration with a large gap height provided the highest downstream performance at blowing ratio of 0.5 and 1.0 with respect to other cases studied. Moreover, the downstream film cooling performance was enhanced far along the spanwise direction for the CHT cases studied and it has the highest value near the scheme exit for parallel configuration. In addition, the impingement configuration enhanced the upper stream cooling performance compared to parallel flow and it was further enhanced for large gap heights. Keywords: film cooling effectiveness, heat transfer coefficient ratio, louver, hybrid, TLC, NHFR, CHT.