Impact of Cooling Injection on Shock Wave over a Flat Tip in High Pressure Turbine

2021 ◽  
pp. 1-31
Author(s):  
Haiteng Ma ◽  
Wei Zeng ◽  
Hongmei Jiang ◽  
Jun Hong
Keyword(s):  
Experimental Data ◽  
Shock Wave ◽  
Nusselt Number ◽  
Wave Structure ◽  
Suction Side ◽  
Pressure Side ◽  
Shock Train ◽  
Shock Density ◽  
Cooling Design ◽  
Transient Thermal

Abstract Cooling design of highly-loaded turbine blade tips is challenged by the scarcity of experimental data and the lack of physical understanding in cooling and over-tip leakage (OTL) interaction under transonic conditions. To address these issues, this paper carried out transient thermal measurements through infrared thermography on a transonic flat tip with and without cooling injection. Experimental data of Nusselt number and cooling effectiveness were obtained and compared with computational fluid dynamics results for numerical validation. Both experimental data and simulation results show that cooling injection drastically augments tip Nusselt number near pressure side which is upstream of ejection, and in areas around coolant holes. Moreover, a strikingly low Nusselt number stripe is observed downstream of cooling injection from one of the holes in aft portion of blade. The strip is directed transverse to local OTL streamline flowing from pressure to suction side and sprawls to adjacent coolant wakes. Further numerical analyses concluded that cooling injection changes tip aerodynamics and overtip shock wave structure fundamentally. Oblique shock waves across uncooled flat tip are replaced by a confined shock train downstream of cooling injection and between cooling holes, which is constituted by two shocks normal to local OTL flow coming from pressure side. Across the first shock, density and pressure increases abruptly, contributing to thickening of tip boundary layer and the plummet of skin friction on tip surface, which is responsible for the sharp decline of tip Nusselt number and therefore, formation of low heat transfer stripe downstream cooling injection.

scholarly journals Approximate Analytical Models of Shock-Wave Structure at Steady Mach Reflection

Fluids ◽  
2021 ◽  
Vol 6 (9) ◽  
pp. 305
Author(s):  
Mikhail V. Chernyshov ◽  
Karina E. Savelova ◽  
Anna S. Kapralova
Keyword(s):  
Experimental Data ◽  
Shock Wave ◽  
Comparative Analysis ◽  
Analytical Model ◽  
Mach Reflection ◽  
Supersonic Jet ◽  
Wave Structure ◽  
Analytical Models ◽  
Analytical Prediction ◽  
Shock Wave Structure

In this study, we obtain the comparative analysis of methods of quick approximate analytical prediction of Mach shock height in planar steady supersonic flows (for example, in supersonic jet flow and in narrowing channel between two wedges), that are developed since the 1980s and being actively modernized now. A new analytical model based on flow averaging downstream curved Mach shock is proposed, which seems more accurate than preceding models, comparing with numerical and experimental data.

Numerical Study on Heat Transfer and Flow Characteristics in Double Turning Areas Ribbed Serpentine Channel With Lateral Outflow

2019 ◽  
Author(s):  
Bo-lun Zhang ◽  
Hui-ren Zhu ◽  
Tao Guo ◽  
Chun-yi Yao ◽  
Zhong-yi Fu
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Numerical Study ◽  
Pressure Coefficient ◽  
Flow Characteristics ◽  
Suction Side ◽  
Pressure Side ◽  
Maximum Increase ◽  
Serpentine Channel ◽  
Ratio Condition

Abstract The double turning areas ribbed serpentine channel with lateral outflow is an important structure for designing the internal systems of turbine blade. The current work similarly simplifies the internal channel of the real blade. The Nusselt number and pressure coefficient distribution of the double turning areas ribbed serpentine channel with different outflow ratios are numerically researched under static and rotating conditions. The Realizable k-ε turbulence model with enhanced wall treatment is used in the numerical simulation. The inlet Reynolds number is 11000. The rotation numbers vary from 0 to 0.09. Three outflow ratios are 27%/0%/73%, 27%/49%/24% and 27%/73%/0%, respectively. The rotation radius (R) is 46.4d. The result shows that the Nusselt number distribution of the passage 3 under 27%/49%/24% outflow ratio condition is similar to that under 27%/73%/0% outflow ratio condition. There is a large low Nusselt number area in the passage 3 under Dr = 27%/0%/73% condition. The averaged area Nusselt number ratios on the suction side of the passage 1, passage 2 and passage 3 are higher than that on the pressure side under nonrotating condition. Rotation enhances heat transfer on the suction side of the passage 2, and has a positive effect on pressure side heat transfer of passage 1 and passage 3. The averaged area Nusselt number ratio of passage 3 under 27%/73%/0% outflow ratio condition is higher than that under other outflow ratio conditions. With the rotation number increasing, the pressure coefficient of the complete ribbed serpentine channel gradually increases, and the maximum increase is in the first turning area.

Heat Transfer and Flow Structure in a Latticework Duct With Different Sidewalls

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Wei Du ◽  
Lei Luo ◽  
Songtao Wang ◽  
Jian Liu ◽  
Bengt Sunden
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Pressure Drop ◽  
Friction Factor ◽  
Flow Structure ◽  
Suction Side ◽  
Reynolds Numbers ◽  
Pressure Side ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics

Abstract Heat transfer characteristics in a latticework duct with various sidewalls are numerically investigated. The crossing angle is 90 deg and the number of subchannels is eleven on both the pressure side and suction side for each latticework duct. The thickness of the ribs is 8 mm and the distance between adjacent ribs is 24 mm. The investigation is conducted for various Reynolds numbers (11,000 to 55,000) and six different sidewalls. Flow structure, pressure drop, and heat transfer characteristics are analyzed. Results revealed that the sidewall has significant effects on heat transfer and flow structure. The triangle-shaped sidewall provides the highest Nusselt number accompanied by the highest friction factor. The sidewall with a slot shows the lowest friction factor and Nusselt number. An increased slot width decreased the Nusselt number and friction factor simultaneously.

The Development and Mechanisms of the High Pressure Turbine Vane Wake Vortex

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Dun Lin ◽  
Xinrong Su ◽  
Xin Yuan
Keyword(s):  
Shock Wave ◽  
High Pressure ◽  
Vortex Shedding ◽  
Wave Interaction ◽  
Suction Side ◽  
Wake Vortex ◽  
Pressure Waves ◽  
Pressure Side ◽  
Eddy Simulation ◽  
Turbine Vane

The wake vortex is an important origin of unsteadiness and losses in turbines. In this paper, the development and underlying mechanisms of the shedding vortex of a high-pressure transonic turbine vane are studied and analyzed using the delayed detached eddy simulation (DDES) and proper orthogonal decomposition (POD). The goal is to understand the unsteadiness related to the wake vortex shedding and the wake evolution and mixing. Special attention is paid to the development of the wake vortex and the mechanisms behind the length characteristics. Interactions of the wake vortex with the shock wave and pressure waves are also discussed. First, the DDES simulation results are compared with published experimental data, Reynolds Averaged Navier-Stokes, and large eddy simulation (LES) simulations. Then, the development of the vane wake vortex, especially the different length characteristics from the cylinder vortex, is discussed. The reason of stronger pressure-side vortex shedding compared to suction-side vortex shedding is revealed. Wake-shock wave interaction and wake-pressure wave interaction are also investigated. The pressure waves are found to have a stronger effect than the shock wave on the spanwise motion and the dissipation of the wake vortex. An analysis of the losses through the turbine vane passage is carried out to evaluate the contributions of thermal and viscous irreversibilities. Losses analysis also confirms the strong interaction between the wake vortex and pressure waves. After that, POD study of the wake behavior was carried out. The results indicate that the shedding vortex is dominant in the unsteady flow. The phase relation between the pressure side wake vortex (PSVP) and the suction side wake vortex (SSVP) is confirmed.

Experimental and numerical investigations of hole injection on the suction side throat of transonic turbine vanes in a cascade with trailing edge injection

2017 ◽  
Vol 232 (8) ◽  
pp. 1454-1466 ◽  
Author(s):  
Jie Gao ◽  
Ming Wei ◽  
Yunning Liu ◽  
Qun Zheng ◽  
Ping Dong
Keyword(s):  
Shock Wave ◽  
Mass Flow ◽  
Suction Side ◽  
Hole Injection ◽  
Pressure Side ◽  
Trailing Edge ◽  
Transonic Flows ◽  
Pressure Distributions ◽  
Numerical Predictions ◽  
Mach Numbers

Trailing-edge mixing flows associated with coolant injection are complex, in particular at transonic flows, and result in significant aerodynamics losses. The objective of this paper is to evaluate the impacts of hole injection near the suction side throat on shock wave control and aerodynamic losses. A series of tests and calculations on effects of hole injection on the suction-side throat of a high-pressure turbine vane cascade with and without trailing-edge injection were conducted. Wake traverses with a five-hole probe and tests of pressure distributions on the turbine profile were taken for total injection mass flow ratios of 0% and 1.2% under test Mach numbers of 0.7, 0.78, and 0.87. Meantime, numerical predictions are carried out for exit isentropic Mach numbers of 0.7, 0.78, 0.87, and 1.1 and hole-injection mass flow ratios of 0%, 0.17%, 0.3%, and 0.89%. Numerical predictions show a reasonable agreement with the experimental data, and wake total pressure losses and flow angles as well as pressure distributions on the turbine profile were compared to calculations without hole injection, indicating a significant effect of hole injection on the profile wake development and its blockage effect on the shock-wave flow in the vane cascade passage. At subsonic flows, the hole injection on the suction side throat thickens the suction-side boundary layer, and increases the flow mixing, thus causing increased wake losses and flow angles. At transonic flows, while the trailing-edge injection reduces the strength of the shock wave at the trailing-edge pressure side, the hole injection on the suction side throat alters the local pressure fields, and then tends to enhance the shock-wave at the trailing-edge pressure-side; however, it seems to reduce the strength of the shock-wave at the trailing-edge suction side.

scholarly journals Nematic Dispersive Shock Waves from Nonlocal to Local

2021 ◽  
Vol 11 (11) ◽  
pp. 4736
Author(s):  
Saleh Baqer ◽  
Dimitrios J. Frantzeskakis ◽  
Theodoros P. Horikis ◽  
Côme Houdeville ◽  
Timothy R. Marchant ◽  
...  
Keyword(s):  
Shock Wave ◽  
Liquid Crystals ◽  
Shock Waves ◽  
Numerical Solutions ◽  
Wave Structure ◽  
Beam Power ◽  
Input Beam ◽  
Shock Wave Structure ◽  
Wave Solutions ◽  
Modulation Theory

The structure of optical dispersive shock waves in nematic liquid crystals is investigated as the power of the optical beam is varied, with six regimes identified, which complements previous work pertinent to low power beams only. It is found that the dispersive shock wave structure depends critically on the input beam power. In addition, it is known that nematic dispersive shock waves are resonant and the structure of this resonance is also critically dependent on the beam power. Whitham modulation theory is used to find solutions for the six regimes with the existence intervals for each identified. These dispersive shock wave solutions are compared with full numerical solutions of the nematic equations, and excellent agreement is found.

The double shock wave structure in the solar wind

1967 ◽  
Vol 72 (21) ◽  
pp. 5275-5286 ◽  
Author(s):  
G. Schubert ◽  
W. D. Cummings
Keyword(s):  
Shock Wave ◽  
Solar Wind ◽  
Wave Structure ◽  
Shock Wave Structure

scholarly journals Aerothermal Investigations of Mixing Flow Phenomena in Case of Radially Inclined Ejection Holes at the Leading Edge

1999 ◽  
Author(s):  
Dieter E. Bohn ◽  
Karsten A. Kusterer
Keyword(s):  
Flow Field ◽  
Secondary Flow ◽  
Gas Turbines ◽  
Leading Edge ◽  
Suction Side ◽  
Pressure Side ◽  
Blade Surface ◽  
Cooling Fluid ◽  
Flow Phenomena ◽  
Vortex Systems

A leading edge cooling configuration is investigated numerically by application of a 3-D conjugate fluid flow and heat transfer solver, CHT-Flow. The code has been developed at the Institute of Steam and Gas Turbines, Aachen University of Technology. It works on the basis of an implicit finite volume method combined with a multi-block technique. The cooling configuration is an axial turbine blade cascade with leading edge ejection through two rows of cooling holes. The rows are located in the vicinity of the stagnation line, one row is on the suction side, the other row is on the pressure side. The cooling holes have a radial ejection angle of 45°. This configuration has been investigated experimentally by other authors and the results have been documented as a test case for numerical calculations of ejection flow phenomena. The numerical domain includes the internal cooling fluid supply, the radially inclined holes and the complete external flow field of the turbine vane in a high resolution grid. Periodic boundary conditions have been used in the radial direction. Thus, end wall effects have been excluded. The numerical investigations focus on the aerothermal mixing process in the cooling jets and the impact on the temperature distribution on the blade surface. The radial ejection angles lead to a fully three dimensional and asymmetric jet flow field. Within a secondary flow analysis it can be shown that complex vortex systems are formed in the ejection holes and in the cooling fluid jets. The secondary flow fields include asymmetric kidney vortex systems with one dominating vortex on the back side of the jets. The numerical and experimental data show a good agreement concerning the vortex development. The phenomena on the suction side and the pressure side are principally the same. It can be found that the jets are barely touching the blade surface as the dominating vortex transports hot gas under the jets. Thus, the cooling efficiency is reduced.

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