The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform

Zhenping Feng - One of the best experts on this subject based on the ideXlab platform.

  • Numerical Study on Effects of Jet Nozzle Angle and Number on Vortex Cooling Behavior for Gas Turbine Blade Leading Edge
    Volume 5B: Heat Transfer, 2016
    Co-Authors: Changhe Du, Liang Li, Xiuxiu Chen, Zhenping Feng
    Abstract:

    Vortex cooling is a promising blade cooling technique for its excellent heat transfer and pressure loss control behavior. In this paper, the proper vortex chamber model is utilized for vortex cooling mechanism analysis. Three dimensional viscous steady Reynolds Averaged Navier-Stokes (RANS) equations are adopted to explore the influences of Jet Nozzle angle and number on vortex cooling flow and thermal performance. Turbulence model verification and grid independence analysis are conducted to determine the suitable turbulence model and mesh number for calculations. Results show that due to obvious mass flux enhancement downstream, stronger axial impact effect will generate, leading to the high Nusselt number region downstream deflection towards outlet. As Jet Nozzle angle increases from α=60° to α=120°, the static pressure ratio increases for the upstream region and decreases for the downstream region, and the total pressure loss ratio increases. The rotation movement and heat transfer intensity will decrease when Jet Nozzle angle changes away from α=90°. The air Jetting velocity decreases and the static pressure ratio increases with the increasing Jet Nozzle number. When Jet Nozzle angle increases from 1 to 11, the total pressure loss ratio decreases and the heat transfer intensity increases at first and then decreases.

  • effect of Jet Nozzle geometry on flow and heat transfer performance of vortex cooling for gas turbine blade leading edge
    Applied Thermal Engineering, 2016
    Co-Authors: Changhe Du, Liang Li, Xin Wu, Zhenping Feng
    Abstract:

    In this paper, 3D viscous steady Reynolds Averaged Navier–Stokes (RANS) equations are utilized to investigate the influence of Jet Nozzle geometry on flow and thermal behavior of vortex cooling for gas turbine blades. Comparison between calculation with different turbulence models and the experimental data is conducted, and results show that the standard k-ω model provides the best accuracy. The grid independence analysis is performed to obtain the proper mesh number. First, the mechanism of vortex cooling is further discussed, and the pronounced impact of kinetic turbulence intensity, thin thermal boundary layer, violent radial convection and complex vortices on enhanced heat transfer performance is confirmed. Then, seven Jet Nozzle aspect ratios and seven Jet Nozzle to chamber cross section area ratios are selected to research the flow field and thermal characteristics of vortex cooling focusing on the streamline, static pressure ratio, total pressure loss ratio and Nusselt number. It is presented that the Jet Nozzle aspect ratio and Jet Nozzle to chamber cross section area ratio both impose a significant effect on the flow and thermal parameters. The averaged Nusselt number decreases at first and then increases with the increasing Jet Nozzle aspect ratio, reaching highest when aspect ratio equals to 1. The effect of area ratio on averaged Nusselt number is complex. Finally, the heat transfer results in this study are compared with other previous works. Results indicate that good agreement with previous data is achieved, and the enhanced thermal behavior may be acquired by carefully designing and optimizing the vortex chamber geometry.

  • numerical study on the effect of Jet Nozzle aspect ratio and Jet angle on swirl cooling in a model of a turbine blade leading edge cooling passage
    International Journal of Heat and Mass Transfer, 2015
    Co-Authors: Jun Li, Zhenping Feng, Terrence W Simon
    Abstract:

    Abstract In this paper, a numerical simulation is performed to predict swirl cooling of an internal leading edge cooling passage model for a gas turbine blade. The swirling cooling performance and its effectiveness are investigated for cases of two rectangular section inlets that cause flow to impinge tangentially on the internal surface of the circular cooling passage. The effects of aspect ratio of the Jet Nozzle, Jet angle and Reynolds numbers on the local and average flows and heat transfer are investigated. The results indicate that the pressure loss and global area weighted average Nusselt number on the swirl chamber increases with increases of Reynolds number, and increases with decreases of the Jet Nozzle aspect ratio. A correlation of the area weighted average Nusselt number over a range of parameters is suggested. The distribution of Nusselt number over the swirl chamber shows that the thermal stresses will be lowest with a 60° Jet Nozzle angle.

  • Numerical simulation on the effect of Jet Nozzle position on impingement cooling of gas turbine blade leading edge
    International Journal of Heat and Mass Transfer, 2011
    Co-Authors: Zhenping Feng
    Abstract:

    Abstract In this paper, Computational Fluid Dynamics (CFD) simulations are performed to investigate the impingement cooling on internal leading edge region which is stretched by the middle cross section of the first stage rotor blade of GE-E 3 engine high pressure gas turbine. The simulations are carried out for a blade with a single row of circle Jets at five different positions and seven different inlet flow Mach numbers. The results indicate that the global area weighted average Nusselt number at the blade leading edge increases with the increase of Jet Mach number, and increases with the decrease of the distance between the Jet Nozzle and the pressure side. The correlation for the area weighted average Nusselt number as a function of the parameters is derived for the range of the parameters considered. The streamwise length weighted average Nusselt number and the spanwise length weighted average Nusselt number also increase with the decrease of the spacing between the Jet Nozzle and the pressure side, and increase with the increase of Jet Mach number. The side entry Jet is desirable to improve the performance of impingement cooling on turbine leading edge, but the arrangement of the Jet Nozzle and the shape of the internal cooling passage should be further optimized to improve the distribution of the heat transfer coefficient.

Changhe Du - One of the best experts on this subject based on the ideXlab platform.

  • Numerical Study on Effects of Jet Nozzle Angle and Number on Vortex Cooling Behavior for Gas Turbine Blade Leading Edge
    Volume 5B: Heat Transfer, 2016
    Co-Authors: Changhe Du, Liang Li, Xiuxiu Chen, Zhenping Feng
    Abstract:

    Vortex cooling is a promising blade cooling technique for its excellent heat transfer and pressure loss control behavior. In this paper, the proper vortex chamber model is utilized for vortex cooling mechanism analysis. Three dimensional viscous steady Reynolds Averaged Navier-Stokes (RANS) equations are adopted to explore the influences of Jet Nozzle angle and number on vortex cooling flow and thermal performance. Turbulence model verification and grid independence analysis are conducted to determine the suitable turbulence model and mesh number for calculations. Results show that due to obvious mass flux enhancement downstream, stronger axial impact effect will generate, leading to the high Nusselt number region downstream deflection towards outlet. As Jet Nozzle angle increases from α=60° to α=120°, the static pressure ratio increases for the upstream region and decreases for the downstream region, and the total pressure loss ratio increases. The rotation movement and heat transfer intensity will decrease when Jet Nozzle angle changes away from α=90°. The air Jetting velocity decreases and the static pressure ratio increases with the increasing Jet Nozzle number. When Jet Nozzle angle increases from 1 to 11, the total pressure loss ratio decreases and the heat transfer intensity increases at first and then decreases.

  • effect of Jet Nozzle geometry on flow and heat transfer performance of vortex cooling for gas turbine blade leading edge
    Applied Thermal Engineering, 2016
    Co-Authors: Changhe Du, Liang Li, Xin Wu, Zhenping Feng
    Abstract:

    In this paper, 3D viscous steady Reynolds Averaged Navier–Stokes (RANS) equations are utilized to investigate the influence of Jet Nozzle geometry on flow and thermal behavior of vortex cooling for gas turbine blades. Comparison between calculation with different turbulence models and the experimental data is conducted, and results show that the standard k-ω model provides the best accuracy. The grid independence analysis is performed to obtain the proper mesh number. First, the mechanism of vortex cooling is further discussed, and the pronounced impact of kinetic turbulence intensity, thin thermal boundary layer, violent radial convection and complex vortices on enhanced heat transfer performance is confirmed. Then, seven Jet Nozzle aspect ratios and seven Jet Nozzle to chamber cross section area ratios are selected to research the flow field and thermal characteristics of vortex cooling focusing on the streamline, static pressure ratio, total pressure loss ratio and Nusselt number. It is presented that the Jet Nozzle aspect ratio and Jet Nozzle to chamber cross section area ratio both impose a significant effect on the flow and thermal parameters. The averaged Nusselt number decreases at first and then increases with the increasing Jet Nozzle aspect ratio, reaching highest when aspect ratio equals to 1. The effect of area ratio on averaged Nusselt number is complex. Finally, the heat transfer results in this study are compared with other previous works. Results indicate that good agreement with previous data is achieved, and the enhanced thermal behavior may be acquired by carefully designing and optimizing the vortex chamber geometry.

Terrence W Simon - One of the best experts on this subject based on the ideXlab platform.

  • numerical study on the effect of Jet Nozzle aspect ratio and Jet angle on swirl cooling in a model of a turbine blade leading edge cooling passage
    International Journal of Heat and Mass Transfer, 2015
    Co-Authors: Jun Li, Zhenping Feng, Terrence W Simon
    Abstract:

    Abstract In this paper, a numerical simulation is performed to predict swirl cooling of an internal leading edge cooling passage model for a gas turbine blade. The swirling cooling performance and its effectiveness are investigated for cases of two rectangular section inlets that cause flow to impinge tangentially on the internal surface of the circular cooling passage. The effects of aspect ratio of the Jet Nozzle, Jet angle and Reynolds numbers on the local and average flows and heat transfer are investigated. The results indicate that the pressure loss and global area weighted average Nusselt number on the swirl chamber increases with increases of Reynolds number, and increases with decreases of the Jet Nozzle aspect ratio. A correlation of the area weighted average Nusselt number over a range of parameters is suggested. The distribution of Nusselt number over the swirl chamber shows that the thermal stresses will be lowest with a 60° Jet Nozzle angle.

I.A. Fedorov - One of the best experts on this subject based on the ideXlab platform.

  • Effect of the method of secondary-fuel supply on the characteristics of a cw chemical HF laser with a three-Jet Nozzle array
    Quantum Electronics, 2001
    Co-Authors: I.A. Fedorov, M.A. Rotinyan, S V Konkin, Vitalii K Rebone, Nikolai E Tret'yakov
    Abstract:

    The effect of the angle of secondary-fuel injection into a flow of oxidising gas and pressure of an active medium on the energy and spatial characteristics of a cw chemical HF laser with a three-Jet Nozzle array are experimentally studied. It is shown that the intensification of reagent mixing at the output of the Nozzle array with the three-Jet Nozzle-Nozzle-injector scheme due to the secondary-fuel injection at an angle of 20{sup 0} to the direction of oxidising-gas flow enables one to reach a maximum of specific output energy, with the mass hydrogen flow lowered by 20% compared to the case of parallel injection. This is accompanied by a 12% increase in the specific output energy and a 15% shortening of the lasing region. The output energy as large as 50% of the maximum value can be reached at the static pressure of the active medium of about 13 Torr, which enables one to increase the pressure at the output of a diffuser by a factor of two when evacuating exhausted reaction products into the environment. (lasers, active media)

  • Supersonic cw chemical HF laser with a three-Jet Nozzle array
    XII International Symposium on Gas Flow and Chemical Lasers and High-Power Laser Conference, 1998
    Co-Authors: S V Konkin, M.A. Rotinyan, I.A. Fedorov, Vitalii K Rebone, A. P. Adjan, A. A. Belyaev, V. G. Karelskii, Yu. P. Maksimov, N. A. Pirogov
    Abstract:

    An experimental investigation was made of a self-contained supersonic cw chemical HF laser with a 40 cm X 11 cm three- Jet Nozzle array and the Nozzle-Nozzle-Nozzle configuration. Such a Nozzle array made it possible to form an active medium approximately 12 cm long and of high optical quality. The use of a wide-aperture stable optical cavity resulted in generation of a laser beam of square (11 cm X 11 cm) cross section. A specific output energy of approximately 80 Jg-1 was reached.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

  • Experimental investigation of a supersonic cw chemical HF laser with a three-Jet Nozzle array
    Quantum Electronics, 1998
    Co-Authors: S V Konkin, M.A. Rotinyan, I.A. Fedorov, Vitalii K Rebone, A. A. Belyaev, Yu. P. Maksimov, A P Adzhyan, V G Karel'skii, N. A. Pirogov
    Abstract:

    An experimental investigation was made of a self-contained supersonic cw chemical HF laser with a 40 cm x11 cm three-Jet Nozzle array and the Nozzle-Nozzle-Nozzle configuration. Such a Nozzle array made it possible to form an active medium {approx}12 cm long and of high optical quality. The use of a wide-aperture stable optical cavity resulted in generation of a laser beam of square (11 cmx11 cm) cross section. A specific output energy of {approx}80 J g{sup -1} was reached. (lasers and amplifiers)

  • Numerical modelling of a supersonic cw chemical HF laser with a three-Jet Nozzle array
    Quantum Electronics, 1998
    Co-Authors: M.A. Rotinyan, I.A. Fedorov, M. Kh Strelets, Michael L. Shur
    Abstract:

    A simultaneous calculation was made of the processes in the Nozzle array and in the resonator cavity of a supersonic cw chemical HF laser. A numerical investigation of the characteristics of a laser with a three-Jet Nozzle array and the Nozzle - Nozzle - Nozzle configuration was carried out within the framework of the full system of the Navier-Stokes equations. This investigation yielded dependences of the specific output energy and of the lasing zone length on the coefficient of secondary dilution of the active medium with helium for different coefficients representing the excess of the secondary fuel.

  • Supersonic cw chemical HF laser with a three-Jet Nozzle array
    Quantum Electronics, 1996
    Co-Authors: I I Galaev, M.A. Rotinyan, S V Konkin, A M Krivitskii, Vitalii K Rebone, Nikolai E Tret'yakov, I.A. Fedorov
    Abstract:

    An experimental investigation was made of the operational characteristics of a self-contained supersonic cw chemical HF laser. A three-Jet Nozzle array with reagent Jets separated spatially by helium Jets was used. This Nozzle array (replacing its two-Jet analogue) made it possible to increase by a factor of 1.20?1.35 the energy characteristics of the laser and by a factor of 1.4?1.7 (up to 125?150 mm) the length of the active medium, and at the same time reduce by 30% the level of optical inhomogeneities in this medium.

Lj Z Petrovic - One of the best experts on this subject based on the ideXlab platform.

  • time resolved optical emission imaging of an atmospheric plasma Jet for different electrode positions with a constant electrode gap
    Plasma Sources Science and Technology, 2015
    Co-Authors: Dejan Maletic, Nevena Puac, Nenad Selakovic, Sasa Lazovic, G Malovic, Antonije đorđevic, Lj Z Petrovic
    Abstract:

    The aim of this paper is to determine the influence of the position of the electrodes on the range of a plasma Jet, for specific experimental conditions, by using time-resolved optical emission spectroscopy. The optimal position of the electrodes is determined for a fixed gas flow rate and applied excitation voltage. We characterize the helium plasma Jet for different distances from the end of the glass tube, showing detailed results for four different electrode positions from the Jet Nozzle (7, 15, 30 and 50mm). It was found that at the distance of 15mm, the length of the plasma Jet is at its maximum. The highest speeds of the plasma package travelling outside the glass tube of the atmospheric plasma Jet are obtained for the same electrode configuration (15mm from the Jet Nozzle). With the electrodes positioned at smaller distances from the Nozzle, the plasma plume was much shorter, and at the larger distances the plasma did not even leave the glass tube.