The Experts below are selected from a list of 291 Experts worldwide ranked by ideXlab platform

Mingcong Luo - One of the best experts on this subject based on the ideXlab platform.

  • Sensitivity Analysis of Multistage Compressor Characteristics Under the Spray Atomization Effect Using a CFD Model
    Energies, 2019
    Co-Authors: Chunlei Liu, Qun Zheng, Qi Wang, Aqiang Lin, Yuting Jiang, Mingcong Luo
    Abstract:

    In this paper, a CFD model is used to simulate the effect of spray atomization at the compressor inlet on a multistage axial subsonic compressor. Special attention is paid to the change of compressor characteristics with wet compression under different rotating speeds to gain the compressor characteristic lines of wet compression. The effects of pneumatic crushing and blade-wall-collision on water droplets and droplet trajectories are contrasted and analyzed under different spray Conditions. Then, the whole/stage-by-stage compressor performances and the flow field are also investigated under dry and wet cases near the Design Operating Condition. The results indicate that multistage compressor performance can be improved with wet compression under the proper water spaying rate and a small droplet size. The influence of pneumatic crushing on the water droplets below 20 μm can be ignored, and the effect of blade collision on water droplets above 5μm should be considered in the wet compression Conditions. Compared to the dry compression, as measured by volume flow, wet compression with proper spaying Conditions makes the front stages operate within a relatively high flow range and the back stages operate within a relatively low flow range. Additionally, the Operating state with wet compression is opposite to the compressor Operating near the surge boundary, which presents the phenomenon of “former surged and back blocking”.

  • The Effect of Wet Compression on a Multistage Subsonic Compressor
    Journal of Turbomachinery, 2013
    Co-Authors: Mingcong Luo, Qun Zheng, Lanxin Sun, Qingfeng Deng, Junjie Yang
    Abstract:

    In this paper, wet compression effect on an eight-stage axial subsonic compressor is simulated by steady numerical methods. Special attention is paid to the compressor Design Operating Condition and rotating stall boundary to contrast and analyze the changes, such as the compressor performance and the flow-field characteristics under dry and wet Conditions. The motions of water droplets are also simulated and analyzed. The results indicate that wet compression could weaken or eliminate the flow separation; improve the flow capacity, efficiency, and pressure ratio of this compressor; and make the compressor Operating near the rotating stall boundary enter into the normal working Condition.

  • Numerical Simulation of an Eight-Stage Axial Subsonic Compressor With Wet Compression
    Volume 5A: Industrial and Cogeneration; Manufacturing Materials and Metallurgy; Marine; Microturbines Turbochargers and Small Turbomachines, 2013
    Co-Authors: Mingcong Luo, Qun Zheng, Lanxin Sun, Qingfeng Deng, Junjie Yang
    Abstract:

    In this paper, wet compression effects on an eight-stage axial subsonic compressor is simulated by steady numerical methods. Special attention is paid to the compressor Design Operating Condition and rotating stall boundary to contrast and analyze the changes such as the compressor performance and the flow field characteristics under dry and wet Conditions. The motions of water droplets are also simulated and analyzed. The results indicate that wet compression could weaken or eliminate the flow separation, improve the flow capacity, efficiency and pressure ratio of this compressor and make the compressor Operating near the rotating stall boundary enter into the normal working Condition.Copyright © 2013 by ASME

Zhang Qian - One of the best experts on this subject based on the ideXlab platform.

  • Distribution of unsteady pressure in volute type axial flow pump
    Journal of Vibroengineering, 2018
    Co-Authors: Cao Weidong, Yao Lingjun, Zhang Qian
    Abstract:

    In order to study the distribution of unsteady pressure in volute type axial flow pump, the k-e turbulence model was applied, and ANSYS CFX was provided for numerical simulation calculation. Experiments of external characteristics and pressure fluctuation have been done to verify the results of numerical simulation. The results show that under the Design Operating Condition, the main fluctuation frequencies in the volute, at the inlet and outlet of the impeller are the blade passing frequency. The amplitudes of fluctuation at the inlet of the impeller decrease gradually from the rim to the hub, while those at the export decrease firstly and then increase, the amplitudes at the tongue are much higher than that at other sections of the volute. Under the off-Design Operating Conditions, the main fluctuation frequency at the inlet and outlet of the impeller is still the blade passing frequency, while that at the tongue is between the twice shaft frequency and the blade passing frequency, fluctuation amplitudes are both larger than those under the Design Operating Condition. Under the Design Operating Condition, the radial force on the impeller is the minimum, however, the axial force increases with the increase of flow rate. The distributions of unsteady pressure in volute type axial flow pump are different with general centrifugal or axial flow pump.

  • Distribution of unsteady pressure in volute type axial flow pump
    'JVE International Ltd.', 2018
    Co-Authors: Cao Weidong, Yao Lingjun, Zhang Qian
    Abstract:

    In order to study the distribution of unsteady pressure in volute type axial flow pump, the k-ε turbulence model was applied, and ANSYS CFX was provided for numerical simulation calculation. Experiments of external characteristics and pressure fluctuation have been done to verify the results of numerical simulation. The results show that under the Design Operating Condition, the main fluctuation frequencies in the volute, at the inlet and outlet of the impeller are the blade passing frequency. The amplitudes of fluctuation at the inlet of the impeller decrease gradually from the rim to the hub, while those at the export decrease firstly and then increase, the amplitudes at the tongue are much higher than that at other sections of the volute. Under the off-Design Operating Conditions, the main fluctuation frequency at the inlet and outlet of the impeller is still the blade passing frequency, while that at the tongue is between the twice shaft frequency and the blade passing frequency, fluctuation amplitudes are both larger than those under the Design Operating Condition. Under the Design Operating Condition, the radial force on the impeller is the minimum, however, the axial force increases with the increase of flow rate. The distributions of unsteady pressure in volute type axial flow pump are different with general centrifugal or axial flow pump

Zhiqiang Wang - One of the best experts on this subject based on the ideXlab platform.

  • Investigations on the Effects of Inflow Condition and Tip Clearance Size to the Performance of a Compressor Rotor
    Journal of Engineering for Gas Turbines and Power, 2014
    Co-Authors: Chenkai Zhang, Zhiqiang Wang
    Abstract:

    To clearly clarify the effects of different upstream boundary layer thickness and tip clearance size to the detailed tip flow field and flow mechanism, numerical simulations are performed on a subsonic compressor rotor, which is used for low-speed model testing of a rear stage embedded in a modern high-pressure compressor. First, available experimental data are adopted to validate the numerical method. Second, comparisons are made for tip leakage vortex (TLV) structure, the interface of leakage flow/mainflow, endwall loss, isentropic efficiency and pressure-rise among different Operating Conditions. Then, effects of different clearance sizes and inflow boundary layer thicknesses are investigated. Finally, the self-induced unsteadiness at one near-stall (NS) Operating Condition is studied for different cases. Results show that the increment of tip clearance size has a deleterious effect on rotor efficiency and pressure-rise performance over the whole Operating range, while thickening the inflow boundary layer is almost the same except that its pressure-rise performance will be increased at mass flow rate larger than Design Operating Condition. Self-induced unsteadiness occurs at NS Operating Conditions, and its appearance largely depends on tip clearance size, while the effect of upstream boundary layer thickness is little.

  • Study on the Effects of Upstream Flow Conditions and Clearance Sizes to Tip Leakage Flow in a Subsonic Large-Scale Rotor
    Volume 2A: Turbomachinery, 2014
    Co-Authors: Chenkai Zhang, Zhiqiang Wang, Ning Ding, Zhiming Mao, Zehua Chen
    Abstract:

    To clearly clarify how it affects the detailed tip clearance flow and flow mechanism by varying the upstream boundary layer thickness and tip clearance size, numerical studies were performed on a subsonic rotor, which is used for low-speed model testing of one rear stage embedded in a modern high-pressure compressor. Firstly, available experimental data were adopted to validate the numerical method. Second, comparisons were made for tip leakage vortex structure, the interface of leakage flow/mainflow, endwall loss, isentropic efficiency and pressure-rise between different Operating Conditions. Then, effects of different clearance sizes and inlet boundary layer thicknesses were investigated. At last, the self-induced unsteadiness at one near-stall Operating Condition was studied for different cases. Results show that increasing the tip clearance size has a deleterious effect on rotor efficiency and pressure-rise performance over the whole Operating range, while thickening the inflow boundary layer is almost the same except that its pressure-rise performance will be increased at mass flow rate larger than Design Operating Condition. Self-induced unsteadiness occurs at near-stall Operating Conditions, and its appearance depends largely on tip clearance size, while upstream boundary layer thickness has little effect.Copyright © 2014 by ASME

Wolfgang Schröder - One of the best experts on this subject based on the ideXlab platform.

  • Analysis of tip-gap size on tip-leakage flow in an axial fan at Design and off-Design Operating Conditions
    13th European Conference on Turbomachinery Fluid Dynamics and Thermodynamics, 2019
    Co-Authors: Seyed Mohsen Alavi Moghadam, Matthias Meinke, Wolfgang Schröder
    Abstract:

    Large-eddy simulations of the flow in a ducted axial fan are performed to investigate the dynamics of tip clearance flow for several tip-gap sizes at Design and off-Design Operating Conditions. The Navier-Stokes equations are solved on a multi-block structured 140-million-cell mesh in a rotating frame of reference for a single out of five blades with periodic boundary Conditions in the circumferential direction and prescribed inflow Conditions based on experimental data. The results show that increasing the tip-gap size results in various vortices in the tip-gap region, i.e., tip-leakage, separation, and induced vortices, which enlarge the diameter and the strength of the main tip vortex. For the off-Design Operating Condition, the tip-gap vortex for the smallest tip-gap size decays faster than that for the Design Operating Condition. For the largest tip clearance, spiral vortex breakdown occurs at the Design Operating Condition.

  • Analysis of tip-leakage flow in an axial fan at varying tip-gap sizes and Operating Conditions
    Computers & Fluids, 2019
    Co-Authors: Seyed Mohsen Alavi Moghadam, Matthias Meinke, Wolfgang Schröder
    Abstract:

    Abstract Detailed and comprehensive analyses of the tip vortex system of a ducted axial fan are performed based on highly resolved large-eddy simulations. Various tip gap sizes, which are typically found in technical fans, and two Operating Conditions are considered. The Reynolds number based on the tip speed of the blade and the diameter of the fan D0 is R e = 9.36 × 10 5 , the Mach number is M = 0.136 , and the rotational speed Ω = 3000  rpm. The chosen tip clearances s are s / D o = 0.001 , 0.005 , 0.01 and the Design and off-Design Operating Conditions are defined by the flow rate coefficients Φ = 0.195 and Φ = 0.165 , respectively. The conservation equations of a compressible, viscous fluid are integrated on a multi-block structured mesh with 140 × 106 grid points in a rotating frame of reference for a single out of five blades using periodic boundary Conditions in the circumferential direction and prescribed undisturbed inflow Conditions based on experimental data. The results show that increasing the tip-gap size results in several vortices in the tip-gap region, i.e., tip leakage, separation and induced vortices, which enlarge the diameter and the strength of the main tip vortex and decrease the efficiency of the fan. For the off-Design Operating Condition, the tip-gap vortex for the smallest tip-gap size decays faster than for the Design Operating Condition. Increasing the tip-gap width, changes the direction of the tip-leakage vortex trajectory. The angle between the blade chord and the tip-leakage vortex is decreased at Design Condition, while the opposite behavior is observed for the off-Design Condition, in which the tip-leakage vortex moves further away from the suction side of the blade. Furthermore, the interaction between the axial flow and the main tip leakage vortex convecting downstream of the blade leads to an enhanced turbulent mixing at larger tip-gap size. For the largest tip clearance, i.e., s / D o = 0.01 , spiral vortex breakdown occurs at the Design Operating Condition caused by the interaction of the main tip vortex with the secondary vortex generated in the tip-gap region. At off-Design Operating Conditions, a larger tip-leakage-loss coefficient is obtained due to a more intensive turbulent mixing, where the maximum loss coefficient occurs at around midchord.

Junjie Yang - One of the best experts on this subject based on the ideXlab platform.

  • The Effect of Wet Compression on a Multistage Subsonic Compressor
    Journal of Turbomachinery, 2013
    Co-Authors: Mingcong Luo, Qun Zheng, Lanxin Sun, Qingfeng Deng, Junjie Yang
    Abstract:

    In this paper, wet compression effect on an eight-stage axial subsonic compressor is simulated by steady numerical methods. Special attention is paid to the compressor Design Operating Condition and rotating stall boundary to contrast and analyze the changes, such as the compressor performance and the flow-field characteristics under dry and wet Conditions. The motions of water droplets are also simulated and analyzed. The results indicate that wet compression could weaken or eliminate the flow separation; improve the flow capacity, efficiency, and pressure ratio of this compressor; and make the compressor Operating near the rotating stall boundary enter into the normal working Condition.

  • Numerical Simulation of an Eight-Stage Axial Subsonic Compressor With Wet Compression
    Volume 5A: Industrial and Cogeneration; Manufacturing Materials and Metallurgy; Marine; Microturbines Turbochargers and Small Turbomachines, 2013
    Co-Authors: Mingcong Luo, Qun Zheng, Lanxin Sun, Qingfeng Deng, Junjie Yang
    Abstract:

    In this paper, wet compression effects on an eight-stage axial subsonic compressor is simulated by steady numerical methods. Special attention is paid to the compressor Design Operating Condition and rotating stall boundary to contrast and analyze the changes such as the compressor performance and the flow field characteristics under dry and wet Conditions. The motions of water droplets are also simulated and analyzed. The results indicate that wet compression could weaken or eliminate the flow separation, improve the flow capacity, efficiency and pressure ratio of this compressor and make the compressor Operating near the rotating stall boundary enter into the normal working Condition.Copyright © 2013 by ASME