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Zachary Daniel Webste - One of the best experts on this subject based on the ideXlab platform.
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effect of internal crossflow Velocity on film cooling effectiveness part ii compound angle shaped holes
ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition, 2017Co-Authors: Joh W Mcclintic, Joshua Anderso, David G Ogard, Thomas E Dyso, Zachary Daniel WebsteAbstract:In gas turbine engines, film cooling holes are commonly fed with an internal crossflow, the magnitude of which has been shown to have a notable effect on film cooling effectiveness. In Part I of this study, as well as in a few previous studies, the magnitude of internal crossflow Velocity was shown to have a substantial effect on film cooling effectiveness of axial shaped holes. There is, however, almost no data available in the literature that shows how internal crossflow affects compound angle shaped film cooling holes. In Part II, film cooling effectiveness, heat transfer coefficient augmentation, and discharge coefficients were measured for a single row of compound angle shaped film cooling holes fed by internal crossflow flowing both in-line and counter to the span-wise direction of coolant injection. The crossflow-to-Mainstream Velocity ratio was varied from 0.2–0.6 and the injection Velocity ratio was varied from 0.2–1.7. It was found that increasing the magnitude of the crossflow Velocity generally caused degradation of the film cooling effectiveness, especially for in-line crossflow. An analysis of jet characteristic parameters demonstrated the importance of crossflow effects relative to the effect of varying the film cooling injection rate. Heat transfer coefficient augmentation was found to be primarily dependent on injection rate, although for in-line crossflow, increasing crossflow Velocity significantly increased augmentation for certain conditions.Copyright © 2017 by ASME
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effect of internal crossflow Velocity on film cooling effectiveness part i axial shaped holes
ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition, 2017Co-Authors: Joh W Mcclintic, Joshua Anderso, David G Ogard, Thomas E Dyso, Zachary Daniel WebsteAbstract:The effect of feeding shaped film cooling holes with an internal crossflow is not well understood. Previous studies have shown internal crossflow reduces film cooling effectiveness from axial shaped holes, but little is known about the mechanisms governing this effect. It was recently shown that the crossflow-to-Mainstream Velocity ratio is important, but only a few of these crossflow Velocity ratios have been studied. This effect is of concern because gas turbine blades typically feature internal passages that feed film cooling holes in this manner. In this study, film cooling effectiveness was measured for a single row of axial shaped cooling holes fed by an internal crossflow with crossflow-to-Mainstream Velocity ratio varying from 0.2–0.6 and jet-to-Mainstream Velocity ratios varying from 0.3–1.7. Experiments were conducted in a low speed flat plate facility at coolant-to-Mainstream density ratios of 1.2 and 1.8. It was found that film cooling effectiveness was highly sensitive to crossflow Velocity at higher injection rates, while it was much less sensitive at lower injection rates. Analysis of the jet shape and lateral spreading found that certain jet characteristic parameters scale well with the crossflow-to-coolant jet Velocity ratio, demonstrating that the crossflow effect is governed by how coolant enters the film cooling holes.Copyright © 2017 by ASME
Zhi Tao - One of the best experts on this subject based on the ideXlab platform.
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experimental investigations of the effects of the injection angle and blowing ratio on the leading edge film cooling of a rotating twisted turbine blade
International Journal of Heat and Mass Transfer, 2018Co-Authors: Feng Han, Zhiyu Zhou, Zhi TaoAbstract:Abstract Experimental investigations were performed to study the effects of the injection angle of cylindrical holes and the blowing ratio on the leading-edge-region film cooling of a twisted turbine blade under rotating conditions. The experiments were carried out at a test facility with a 1-stage turbine using the thermochromic liquid crystal (TLC) technique. All experiments were performed at a rotating speed of 574 rpm with an average blowing ratio ranging from 0.5 to 2.0. The Reynolds number was fixed at 6.3378 × 104 based on the Mainstream Velocity of the turbine outlet and the rotor blade chord length. CO2 was used as the coolant to achieve a coolant-to-Mainstream density ratio of 1.56. The film-hole injection angles tested were 30°, 45° and 60°. The results show that both the injection angle and the blowing ratio have significant impacts on film cooling effectiveness. For α = 30° and α = 45°, the radial average film cooling effectiveness increases as the blowing ratio increases in all regions. For α = 60°, this effectiveness first increases and then decreases as the blowing ratio increases, with the case of M = 1.5 yielding the best average cooling performance. At each blowing ratio, the α = 30° case always yields the highest streamwise average film cooling effectiveness in the region of −4.3
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film cooling performance in a low speed 1 5 stage turbine effects of blowing ratio and rotation
Journal of Enhanced Heat Transfer, 2011Co-Authors: Zhi Tao, Hongwu Deng, Jun Xiao, Xiang LuoAbstract:This paper presents experimental investigations on film cooling performance under rotation in a low-speed 1.5-stage turbine using the thermochromic liquid crystal (TLC) technique. The experiment was accomplished in a test facility which was recently established to study rotating film cooling performance in realistic turbine stages. Eighteen blades of chord length of 0.1243 m and height of 0.099 m were installed in the rotor. A film hole with diameter of 0.004 m, angled 28 degrees and 36 degrees tangentially to the pressure surface and suction surface in streamwise, respectively, was set in the middle span of the rotor blade. All measurements were made at three different rotating speeds of 600, 667 and 702 rpm with the blowing ratios varying from 0.3 to 3.0. The Reynolds number based on the Mainstream Velocity of the turbine outlet and the chord length of the rotor blade was fixed at 1.89 x 10(5). Results show that on the pressure side, the film coverage and cooling effectiveness scaled up with the blowing ratio and the film deflected centrifugally; on the suction side, the maximum film coverage and cooling effectiveness were obtained at moderate blowing ratio and a centripetal deflection of the film was observed. The film deflection could be amplified by either decreasing the blowing ratio or increasing the rotation number on both sides. Overall, blowing ratio and rotation play significant roles in the film cooling performance.
Li Haiwang - One of the best experts on this subject based on the ideXlab platform.
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PIV flow measurements for a rotating square smooth channel heated by basically uniform heat flux
'Elsevier BV', 2018Co-Authors: You Ruquan, Li Haiwang, Wu Hongwei, Tao ZhiAbstract:This document is the Accepted Manuscript of the following article: Ruquan You, Haiwang Li, Hongwei Wu, and Zhi Tao, ‘PIV flow measurements for a rotating square smooth channel heated by basically uniform heat flux’, International Journal of Heat and Mass Transfer, Vol. 119: 236-246, April 2018. Under embargo until 22 December 2018. The final, definitive version is available online at DOI: https://doi.org/10.1016/j.ijheatmasstransfer.2017.11.073, published by Elsevier Ltd.In this paper, we experimentally investigated the Mainstream and secondary flow in a smooth rotating channel with wall heated by particle image velocimetry (PIV). The hybrid effect of Coriolis force and buoyancy force on the Mainstream and secondary flow was taken into consideration in the current work. In the experiments, the Reynolds number, based on the channel hydraulic diameter (D = 80 mm) and the bulk Mainstream Velocity (Vm = 1.82 m/s), is 10,000, and the rotation numbers are 0, 0.13, 0.26, 0.39, respectively. Constant heat flux on the four channel walls are provided by Indium Tin Oxide (ITO) heater glass, the density ratio (d.r.) equaling approximately 0.1. The buoyancy number ranges from 0 to 0.153. The results showed that Coriolis force and buoyancy force have important influences on the flow field in rotating channels. Coriolis force pushes the Mainstream to trailing side, making an asymmetry of the Mainstream. On the cross-section, there is a symmetric two-vortex pair caused by the Coriolis. The two-vortex pair is pushed into the trailing side with the increase of rotation numbers. Then, there are two small vortex appearing near the leading side. Buoyancy force suppresses Mainstream and causes the separation of the flow near the leading side. When the separated flow happened, the structure of secondary flow is disordered near the leading side.Peer reviewedFinal Accepted Versio
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experimental investigation of rotating film cooling performance in a low speed 1 5 stage turbine
International Journal of Heat and Mass Transfer, 2013Co-Authors: Li Guoqing, Zhu Junqiang, Deng Hongwu, Li HaiwangAbstract:Abstract Film cooling performance under rotating condition was investigated in rotor blade of a 1.5-stage turbine using Thermochromic Liquid Crystal (TLC) technique. The turbine is installed in the middle of the experimental apparatus which is a closed-loop, low-speed thermal wind tunnel. The rotor of the turbine includes 18 blades with chord of 124.3 mm and height of 99 mm. A film hole is set in the middle span of rotor blade surface with injection angle of 28° on the pressure side and 36° on the suction side respectively. In the experiments, the Reynolds number based on the Mainstream Velocity of the turbine outlet and the chord length of the rotor blade is fixed at 1.89 × 105. Measurements are made at three different rotating speeds of 600 rpm, 667 rpm and 702 rpm with the blowing ratio varying from 0.3 to 3.0. CO2 and air act as coolant to obtain the density ratio of 1.57 and 1.03, respectively. The effects of blowing ratio, density ratio, rotating number and curved surfaces are analyzed according to the film performance. Comparing with the air injection, the CO2 injection with higher density ratio produces better film attachment. The film coverage and cooling effectiveness increases monotonously on the pressure side while the trend is parabola on the suction side as the blowing ratio rising. The film deflection is analyzed quantitatively. Higher rotating number and lower blowing ratio results in stronger film deflection. Besides, the different characteristics are indicated between the pressure side and the suction side.
D P Mason - One of the best experts on this subject based on the ideXlab platform.
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Symmetry solutions of a thirdorder ordinary differential equation which arises from Prandtl boundary layer equations, Journal Nonlinear Math. Phys. Accepted for publication
2015Co-Authors: R Naz, Fazal M Mahomed, D P MasonAbstract:The similarity solution to Prandtl’s boundary layer equations for two-dimensional and radial flows with vanishing or constant Mainstream Velocity gives rise to a third-order ordinary differential equation which depends on a parameter α. For special values of α the third-order ordinary differential equation admits a three-dimensional symmetry Lie algebra L3. For solvable L3 the equation is integrated by quadrature. For non-solvable L3 the equation reduces to the Chazy equation. The Chazy equation is reduced to a first-order differential equation in terms of differential invariants which is transformed to a Riccati equation. In general the third-order ordinary differential equation admits a two-dimensional symmetry Lie algebra L2. For L2 the differential equation can only be reduced to a first-order equation. The invariant solutions of the third-order ordinary differential equation are also derived.
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symmetry solutions of a third order ordinary differential equation which arises from prandtl boundary layer equations
Journal of Nonlinear Mathematical Physics, 2008Co-Authors: R Naz, F M Mahomed, D P MasonAbstract:The similarity solution to Prandtl's boundary layer equations for two-dimensional and radial flows with vanishing or constant Mainstream Velocity gives rise to a third- order ordinary differential equation which depends on a parameter �. For special values ofthe third-order ordinary differential equation admits a three-dimensional symmetry Lie algebra L3. For solvable L3 the equation is integrated by quadrature. For non-solvable L3 the equation reduces to the Chazy equation. The Chazy equation is reduced to a first-order differential equation in terms of differential invariants which is transformed to a Riccati equation. In general the third-order ordinary differential equation admits a two-dimensional symmetry Lie algebra L2. For L2 the differential equation can only be reduced to a first-order equation. The invariant solutions of the third-order ordinary differential equation are also derived.
Xiaojun Fan - One of the best experts on this subject based on the ideXlab platform.
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numerical simulation on effects of film hole geometry and mass flow on vortex cooling behavior for gas turbine blade leading edge
Applied Thermal Engineering, 2017Co-Authors: Xiaojun FanAbstract:Abstract The vortex chamber model with film holes is established to investigate the effect of film holes on vortex cooling in gas turbine blade leading edge. The 3D viscous steady Reynolds Averaged Navier-Stokes (RANS) equations and the standard k - ω model are utilized for numerical computation. Results show that the existence of film holes has a strong disturbance on the internal flow, which increases the upstream Velocity of film holes and decreases the downstream Velocity. Meanwhile, the heat transfer intensity is enhanced by 5.2% compared to the case without film holes. The pressure coefficient presents a fluctuant decrease for all cases. However, an increase in circumferential angle contributes to a decrease in pressure coefficient. The circumferential angle at 90° is the most suitable considering both average heat transfer coefficient and Nusselt number distribution. When the diameter ratio of film holes increases to 0.1, it has the highest heat transfer intensity. As the mass flow of film holes increases, the Mainstream Velocity, the averaged pressure coefficient C ps and the globally averaged Nusselt number Nu a will decrease.
