Effects of Hole Geometry on Film Coverage and Cooling Capability

2004 ◽  
Author(s):  
J. T. Liu ◽  
X. F. Peng
Keyword(s):  
Numerical Simulation ◽  
Cross Section ◽  
Film Cooling ◽  
Comprehensive Evaluation ◽  
Constant Cross Section ◽  
Shaped Hole ◽  
Hole Geometry ◽  
Definition Of ◽  
Compound Angle

A numerical simulation was conducted to investigate the film effectiveness of film cooling using a single hole with two types of geometry: cylindrical hole with constant cross section and shaped hole with conically widened exit. The film cooling jet was injected through a 30° inclined hole to the surface and with lateral directions of 0°, 45° and 90°, for the blowing rates of 0.5, 1.0 and 2.0, respectively. The film effectiveness analyzing method was discussed based on the simulation. An effort is performed to form a more comprehensive evaluation technology with the definition of three parameters, film coverage, average cooling capability and uniformity of film. The results indicate that the film quality of compound angle injection depends on the equilibrium between the lateral and axial momentum components of coolant jet, and that the film protects the surface effectively at moderate blowing rate. The use of a shaped hole shows noticeable advantage.

scholarly journals Film Cooling Effectiveness and Heat/Mass Transfer Coefficient Measurement Around a Conical-Shaped Hole With a Compound Angle Injection

1999 ◽  
Author(s):  
H. H. Cho ◽  
D. H. Rhee ◽  
B. G. Kim
Keyword(s):  
Mass Transfer ◽  
Film Cooling ◽  
Heat Mass Transfer ◽  
Transfer Coefficients ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Cooling Hole ◽  
Shaped Hole ◽  
Hole Geometry ◽  
Compound Angle

The present study investigates local film cooling effectiveness values and heat/mass transfer coefficients around a conical-shaped film cooling hole with compound angle orientations. Three types of film cooling hole geometry are compared in this study; one is cylindrical hole geometry with constant cross section and the others are shaped hole geometries with conically-enlarged hole exits. The shaped holes have cylindrical passage sections at the hole inlet region to obtain a certain pressure drop through the holes. One shaped hole expands 4° in all directions from the middle of hole to the exit. The other shaped hole has the tilted center-line by 4° between the conical and metering holes and is enlarged by 8° to downstream side. The hole area ratios of the exit to the inlet are 2.55 and 2.48, respectively. The compound-angled film cooling jet is ejected through the single holes, which are inclined at 30° to the surface based on the metering hole and are rotatable in lateral direction from 0° to 90°. The blowing rates are changed from 0.5 to 2.0. The naphthalene sublimation technique is used to determine local heat/mass transfer coefficients and local adiabatic/impermeable wall film cooling effectiveness around the injection hole. The results indicate that the injected jet protects the surface effectively with low blowing rates and spreads more widely with the compound angle injections than the axial injection. For the shaped hole enlarged by 4° in all directions, the penetration of jet is reduced and higher cooling performance is obtained even at relatively high blowing rates because the increased hole exit area reduces hole exit velocity. Furthermore, the film cooling effectiveness is fairly uniform near the hole due to the wide lateral spreading of coolant with the expanded cooling hole exit.

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.

Numerical Investigation on Diffusion Slot Hole With Various Cross-Sectional End Shapes

2017 ◽  
Vol 139 (9) ◽  
Author(s):  
Bai-Tao An ◽  
Jian-Jun Liu
Keyword(s):  
Cross Section ◽  
Film Cooling ◽  
Separation Bubble ◽  
Rectangular Cross Section ◽  
Pressure Ratio ◽  
Smooth Transition ◽  
Shape Variation ◽  
Cross Sectional ◽  
Cooling Effectiveness ◽  
Shaped Hole

The diffusion hole constructed on a slot-type cross section has the potential to obtain high film cooling performance. However, the end shape of the cross section can greatly affect film cooling characteristics. This study examined eight cases of diffusion slot holes with various cross-sectional end shapes. The comparison of the eight diffusion slot holes and a typical fan-shaped hole was performed with a flat plate model using a three-dimensional (3D) steady computational fluid dynamics (CFD) method. The rectangular cross section had an aspect ratio of about 3.4. The end shape variation can be described based on sidewall contraction location, size, and form. The simulations were performed under an engine-representative condition of mainstream inlet Mach number 0.3 and turbulence intensity 5.2%. The simulated results showed that a strip separation bubble caused by inlet “jetting effect” occurs near the downstream wall of the diffusion slot hole and interacts with the diffusion flow. The different end shape of the rectangular cross section leads to different sidewall static pressure and exit velocity profiles, thereby produces three cooling effectiveness patterns, single-peak, bipeak, and tripeak patterns. The tripeak pattern produces higher cooling effectiveness and relatively uniform film coverage. The structure with moderate contraction and smooth transition on two sides of the downstream wall favors creation of a tripeak pattern. Compared with the fan-shaped hole, the discharge coefficient of diffusion slot hole is slightly small in low pressure ratio range, the pressure loss ratio has little difference.

Film Cooling Investigation of a Slot-Based Diffusion Hole

2016 ◽  
Author(s):  
Bai-Tao An ◽  
Jian-Jun Liu ◽  
Si-Jing Zhou ◽  
Xiao-Dong Zhang ◽  
Chao Zhang
Keyword(s):  
Cross Section ◽  
Film Cooling ◽  
Rectangular Cross Section ◽  
Density Ratio ◽  
Vortex Structures ◽  
Cross Sectional ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Shaped Hole

This paper presents a new configuration of discrete film hole, i.e., the slot-based diffusion hole. Retaining the similar diffusion features to a traditional diffusion hole, the slot-based diffusion hole transforms the cross section of circle for the traditional diffusion hole to a flattened rectangle with respect to the equivalent cross-sectional area. Consequently, the exit width of the new hole is effectively enlarged. To verify the film cooling effectiveness, a low speed flat plate experimental facility incorporated with Pressure Sensitive Paint (PSP) measurement technique was employed to obtain the adiabatic film cooling effectiveness. The experiments were performed with hole pitch to diameter ratio p/D=6 and density ratio DR=1.38. The blowing ratio was varied from M=0.5 to M=2.5. A fan-shaped hole and two slot-based diffusion holes were tested and compared. Three-dimensional numerical simulation was employed to analyze the flow field in detail. The experimental results showed that the area averaged effectiveness of two slot-based diffusion holes is significantly higher than that of the fan-shaped hole when the blowing ratio exceeds 1.0. The slot-based diffusion hole demonstrates the great advantage over the fan-shaped hole at hole exit and maintains this to far downstream. The numerical results showed that the ends shape of the flattened rectangular cross section has large influences on film distribution patterns and downstream vortex structures. The semi-circle and straight line ends shapes lead to a bi-peak and a single-peak effectiveness pattern, respectively. The optimal ends shape can regulate the vortex structures and improve the film cooling effectiveness further.

Influence of Coolant Density on Turbine Blade Film-Cooling With Compound-Angle Shaped Holes

2012 ◽  
Author(s):  
Kevin Liu ◽  
Shang-Feng Yang ◽  
Je-Chin Han
Keyword(s):  
Film Cooling ◽  
Momentum Flux ◽  
Density Ratio ◽  
Flux Ratio ◽  
Suction Side ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Shaped Hole ◽  
Compound Angle

Adiabatic film-cooling effectiveness is examined systematically on a typical high pressure turbine blade by varying three critical flow parameters: coolant blowing ratio, coolant-to-mainstream density ratio, and freestream turbulence intensity. Three average coolant blowing ratios 1.0, 1.5, and 2.0; three coolant density ratios 1.0, 1.5, and 2.0; two turbulence intensities 4.2% and 10.5%, are chosen for this study. Conduction-free pressure sensitive paint (PSP) technique is used to measure film-cooling effectiveness. Three foreign gases — N2 for low density, CO2 for medium density, and a mixture of SF6 and Argon for high density are selected to study the effect of coolant density. The test blade features 45° compound-angle shaped holes on the suction side and pressure side, and 3 rows of 30° radial-angle cylindrical holes around the leading edge region. The inlet and the exit Mach number are 0.27 and 0.44, respectively. Reynolds number based on the exit velocity and blade axial chord length is 750,000. Results reveal that the PSP is a powerful technique capable of producing clear and detailed film effectiveness contours with diverse foreign gases. As blowing ratio exceeds the optimum value, it induces more mixing of coolant and mainstream. Thus film-cooling effectiveness reduces. Greater coolant-to-mainstream density ratio results in lower coolant-to-mainstream momentum and prevents coolant to lift-off; as a result, film-cooling increases. Higher freestream turbulence causes effectiveness to drop everywhere except in the region downstream of suction side. Results are also correlated with momentum flux ratio and compared with previous studies. It shows that compound shaped hole has the greatest optimum momentum flux ratio, and then followed by axial shaped hole, compound cylindrical hole, and axial cylindrical hole.

Investigation of Film Cooling Effectiveness of Full-Coverage Inclined Multihole Walls With Different Hole Arrangements

2003 ◽  
Author(s):  
Yuzhen Lin ◽  
Bo Song ◽  
Bin Li ◽  
Gaoen Liu ◽  
Zhiyong Wu
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Film Cooling ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Full Coverage ◽  
Inclination Angles ◽  
Combustor Liner ◽  
Compound Angle

An experimental and numerical investigation of adiabatic film cooling effectiveness was conducted on four full-coverage inclined multihole walls with different hole arrangements. The hole geometrical patterns and the test conditions were chosen to be representative of film cooling designs for modern aeroengine combustor liners. The four hole arrangements were grouped into two types based on lateral hole pitch ( P ) and streamwise row spacing ( S ). One type included two test plates which had the same S and P (S/P = 2) and compound angle (β = 0 deg) but different hole inclination angles ( α ) (30 and 150 deg ). The other type included two test plates which had the same S and P (but S/P = 1) and inclination angle (α = 30 deg) but different compound angles (0 deg and 50 deg). Heat-mass transfer analogy method was employed to investigate the adiabatic film cooling effectiveness of these multihole walls with typical blowing ratios for aeroengine combustors. The numerical simulation was performed to characterize the flowfield and temperature distribution, aiming to further understand the film cooling mechanisms. The experimental results indicated that blowing ratio within the range from 1 to 4 had negligible influence on adiabatic film cooling effectiveness (η) in the case of concurrent coolant injection while hole arrangement had large effect on η. But the blowing ratio within the range from 1 to 4 had large effect on the film cooling effectiveness for the counterflow film cooling scheme. The numerical results were compared with experimental data and fairly good agreement was obtained. The numerical simulation revealed the flow structure, particularly exhibiting significant influence of the interaction between mainstream flow and coolant jets on η. With validation by experimental data, film cooling numerical simulation seems quite helpful in selecting optimum multihole arrangement for modern combustor liner design.

scholarly journals EVALUATION OF NATURAL GAS QUALITY BY ITS CALORIFIC VALUE

2021 ◽  
Vol 82 (1) ◽  
pp. 30-36
Author(s):  
Vasil Motalo ◽  
◽  
Bohdan Stadnyk ◽  
Andrij Motalo ◽  
◽  
...  
Keyword(s):  
Energy Source ◽  
Natural Gas ◽  
Comprehensive Evaluation ◽  
Energy Content ◽  
Calorific Value ◽  
Component Composition ◽  
Definition Of ◽  
Own Gas ◽  
Experimental Researches

The article develops and analyzes a method of the comprehensive evaluation of the quality of natural gas as an energy source. The method is based on establishing the calorific value of natural gas as a determinative index of its quality, taking into account all gas properties: both those that positively affect the gas calorific value and its energy content, and those that adversely affect. The generalized definition of natural gas quality as the degree to which the set of the own gas characteristics (component composition and physical properties) meet the requirements concerning energy content, safety, ecology, and other factors is given. The results of experimental researches on natural gas quality according to the developed procedure are also presented.

scholarly journals DEVELOPMENT OF INFORMATION TECHNOLOGY FOR COMPLEX EVALUATION OF HIGHER EDUCATION INSTITUTIONS

2019 ◽  
Vol 73 (5) ◽  
pp. 293-306 ◽  
Author(s):  
Valeriy Yu. Bykov ◽  
Oleksandr Yu. Kuchanskyi ◽  
Andrii O. Biloshchytskyi ◽  
Yurii V. Andrashko ◽  
Oleksandr V. Dikhtiarenko ◽  
...  
Keyword(s):  
Higher Education ◽  
Comprehensive Evaluation ◽  
Higher Education Institutions ◽  
Multidimensional Space ◽  
International Programs ◽  
Complex Evaluation ◽  
Definition Of ◽  
International Systems ◽  
Educational Component

This paper presents a method for complex evaluation of higher education institutions based on a generalized volume of m-simplex calculation. Every kind of activities of higher education institutions (educational, scientific, innovative, etc.) determines an axis in the multidimensional space used to build the m-simplex. After evaluating higher education institutions in the specified m-activities, the points are put on the respective axis. M-simplex with vertices in these points is built. The generalized volume of this m-simplex, which is calculated based on the Cayley-Menger determinant, defines the integral quantitative assessment of higher education institutions’ activities. To verify the specified method for evaluating higher education institutions, we reviewed well-known evaluation methods and described some types of activities that could be used as a basis for a definition of the axes on which the m-simplex is built. The research component of higher education institutions’ activities is determined by the volume of articles published and their citations in international scientometric databases. The educational component relates to the quality of graduates, their competitiveness in the labour-market. The international component concerns the participation of higher education institutions and their departments in international programs and projects. The described method could be used to monitor the activities of higher education institutions and their separate structural subdivisions. The results of the monitoring are important for a comprehensive evaluation of scientific, educational, international, innovative and other types of activities of higher education institutions in a particular region and the country as a whole. In this article, we have formed a list of indicators, according to which several Ukrainian higher education institutions were evaluated. Besides, the comparison of quantitative evaluations with ratings of higher education institutions in international systems of university activities evaluation was made.

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