The Experts below are selected from a list of 1656 Experts worldwide ranked by ideXlab platform

Hang Zhao - One of the best experts on this subject based on the ideXlab platform.

  • the impact of Casing groove location on the flow instability in a counter rotating axial flow compressor
    Aerospace Science and Technology, 2018
    Co-Authors: Xiaochen Mao, Bo Liu, Tianquan Tang, Hang Zhao
    Abstract:

    Abstract To make up the lack of the experimental and numerical investigations about the grooved Casing Treatment (CT) applied in counter-rotating axial flow compressors (CRAC), the effects of circumferential single grooved CT on the stability enhancement were investigated in the rear rotor of a low-speed CRAC with numerical simulations. The main purpose was to gain a better understanding of the application principle of Casing groove and the associated control mechanisms in the CRAC. Parametric studies show that the optimal position of the groove should be located near the blade leading edge in terms of stall margin improvement (SMI) and efficiency enhancement at the near stall condition. Due to the impact of Casing groove on tip leakage flow (TLF), the blade tip unloading effect, redirection effect and the compound effect of suction–injection are all beneficial to the SMI. Detailed observation of flow structures illustrates that it is more effective to improve flow stability by controlling the critical TLF released from about mid-chord and the stall inception process may be probably changed due to the direct effect of groove on the main TLF released near the blade leading edge. Additionally, the effects that the groove has on rotor outflow blockage, backward axial momentum flux and TLF momentum perpendicular to the blade tip camber inside the tip gap are also studied in the paper.

  • numerical analysis of the circumferential grooves Casing Treatment in a counter rotating axial flow compressor
    Applied Thermal Engineering, 2018
    Co-Authors: Xiaochen Mao, Bo Liu, Hang Zhao
    Abstract:

    Abstract The impact of the circumferential grooves Casing Treatment over the rear rotor (R2) in a counter-rotating axial flow compressor has been investigated based on numerical simulations. The main purpose is to understand the effects of grooved Casing Treatment on the unsteady flow behaviors and the corresponding mechanisms of the stability enhancement in the compressor. The results show that the interface between incoming main flow and tip leakage flow in R2 is pushed downstream obviously and the flow stability is enhanced with grooved Casing Treatment. The compressor performance at near stall condition is also improved remarkably. The blade loading below the grooves, the incidence angle near the blade tip and the backward axial momentum flux injected into main flow passage through the tip gap are all reduced, which is beneficial to the stall margin improvement. Frequency analysis near the blade tip of R2 indicates that the oscillations with lower frequency are suppressed by the Casing grooves and the fluctuating intensity decreases, which also contributes for the enhancement of flow stability. Detailed observation of tip leakage flow structures illustrates that it is more effective to improve the flow stability by controlling the tip leakage flow released from near mid-chord.

Xiaochen Mao - One of the best experts on this subject based on the ideXlab platform.

  • investigation of the Casing groove location effect for a large tip clearance in a counter rotating axial flow compressor
    Aerospace Science and Technology, 2020
    Co-Authors: Xiaochen Mao, Bo Liu
    Abstract:

    Abstract In the present work, the location effect of single grooved Casing Treatment (CT) on the compressor performance and flow stability are numerically studied at a large tip clearance in a two-stage counter-rotating axial flow compressor. The results show that the first stall stage is changed from the rear rotor (R2) to the front rotor (R1) as the tip clearance is increased from the normal design tip clearance (τ) to a large tip clearance of 2τ. The compressor stability can only be improved by the CT schemes in R1 without obvious change of compressor efficiency, while the compressor efficiency at near stall point can be increased remarkably for the effective CT configurations in R2 without stall margin improvement (SMI). The stall inception type may be changed for the least effective CT configuration in R1 due to the drastic change of flow structure of the tip leakage flow (TLF) released from near the blade leading edge. Detailed analysis of TLF structure shows that it is advisable to improve the compressor flow stability by controlling the TLF part which is released from the blade chord range away from the blade leading edge. After the application of effective CT schemes, the tip flow field is improved in the corresponding rotor and the interface is pushed further downwards to a different extent resulting in the reduction of the TLF intensity and loss generation.

  • the impact of Casing groove location on the flow instability in a counter rotating axial flow compressor
    Aerospace Science and Technology, 2018
    Co-Authors: Xiaochen Mao, Bo Liu, Tianquan Tang, Hang Zhao
    Abstract:

    Abstract To make up the lack of the experimental and numerical investigations about the grooved Casing Treatment (CT) applied in counter-rotating axial flow compressors (CRAC), the effects of circumferential single grooved CT on the stability enhancement were investigated in the rear rotor of a low-speed CRAC with numerical simulations. The main purpose was to gain a better understanding of the application principle of Casing groove and the associated control mechanisms in the CRAC. Parametric studies show that the optimal position of the groove should be located near the blade leading edge in terms of stall margin improvement (SMI) and efficiency enhancement at the near stall condition. Due to the impact of Casing groove on tip leakage flow (TLF), the blade tip unloading effect, redirection effect and the compound effect of suction–injection are all beneficial to the SMI. Detailed observation of flow structures illustrates that it is more effective to improve flow stability by controlling the critical TLF released from about mid-chord and the stall inception process may be probably changed due to the direct effect of groove on the main TLF released near the blade leading edge. Additionally, the effects that the groove has on rotor outflow blockage, backward axial momentum flux and TLF momentum perpendicular to the blade tip camber inside the tip gap are also studied in the paper.

  • numerical analysis of the circumferential grooves Casing Treatment in a counter rotating axial flow compressor
    Applied Thermal Engineering, 2018
    Co-Authors: Xiaochen Mao, Bo Liu, Hang Zhao
    Abstract:

    Abstract The impact of the circumferential grooves Casing Treatment over the rear rotor (R2) in a counter-rotating axial flow compressor has been investigated based on numerical simulations. The main purpose is to understand the effects of grooved Casing Treatment on the unsteady flow behaviors and the corresponding mechanisms of the stability enhancement in the compressor. The results show that the interface between incoming main flow and tip leakage flow in R2 is pushed downstream obviously and the flow stability is enhanced with grooved Casing Treatment. The compressor performance at near stall condition is also improved remarkably. The blade loading below the grooves, the incidence angle near the blade tip and the backward axial momentum flux injected into main flow passage through the tip gap are all reduced, which is beneficial to the stall margin improvement. Frequency analysis near the blade tip of R2 indicates that the oscillations with lower frequency are suppressed by the Casing grooves and the fluctuating intensity decreases, which also contributes for the enhancement of flow stability. Detailed observation of tip leakage flow structures illustrates that it is more effective to improve the flow stability by controlling the tip leakage flow released from near mid-chord.

Wuli Chu - One of the best experts on this subject based on the ideXlab platform.

  • flow mechanism of affecting an axial flow compressor performance and stability with cross blade slot Casing Treatments
    Proceedings of the Institution of Mechanical Engineers Part A: Journal of Power and Energy, 2019
    Co-Authors: Haoguang Zhang, Wuli Chu, Xudong Zhang, Haiyang Kuang
    Abstract:

    The objective of this study is to evaluate the effect of cross-blade slot Casing Treatment on the stability and performance of an axial flow compressor rotor. The experimental and unsteady calculat...

  • Mechanism study of performance enhancement in a subsonic axial flow compressor with recirculating Casing Treatment
    Proceedings of the Institution of Mechanical Engineers Part G: Journal of Aerospace Engineering, 2017
    Co-Authors: Wei Wang, Wuli Chu, Haoguang Zhang
    Abstract:

    The improvements in both compressor efficiency and stability have been observed in a subsonic axial flow compressor with recirculating Casing Treatment. The study aims to understand the underlying ...

  • Flow Control by Slot Position and Noise Baffle in a Self-Recirculation Casing Treatment on an Axial Fan-Rotor
    Hindawi Limited, 2017
    Co-Authors: Stephen Spence, Wuli Chu, Hua Chen, Lee Gibson
    Abstract:

    To address the situations where the Casing Treatment needs to be used to stabilize axial compressors through strong recirculation, this paper initiated a CFD study to investigate how the flow could be suitably controlled in the Casing Treatment to minimize the efficiency penalty and increase the flow range. A counter-swirl self-recirculation Casing Treatment was first designed on a low speed axial fan rotor as a baseline case. Then three different slot positions and the influence of including the noise baffle were numerically studied. Based on the understanding of their coeffects, the shorter noise baffle was considered and it was found that the highest efficiency was achieved in the case of the upstream slot when the length of baffle was suitably adjusted to balance the incoming flow and recirculation. The largest flow range was achieved by locating the slot at the most downstream position and using a 50% length baffle since it suitably controlled the recirculating flow and relieved the separation at the low-span region. An optimization study showed that the optimum length of the baffle for efficiency was always larger than for the flow range. Both of the two optimum values reduce as the slot moves downstream

  • Numerical Investigations of the Coupled Flow Through a Subsonic Compressor Rotor and Axial Skewed Slot
    Journal of Turbomachinery, 2009
    Co-Authors: Wuli Chu, Junqiang Zhu, Yangfeng Zhang
    Abstract:

    In order to advance the understanding of the fundamental mechanisms of axial skewed slot Casing Treatment and their effects on the subsonic axial-flow compressor flow field, the coupled unsteady flow through a subsonic compressor rotor and the axial skewed slot was simulated with a state-of-the-art multiblock flow solver. The computational results were first compared with available measured data, that showed the numerical procedure calculates the overall effect of the axial skewed slot correctly. Then, the numerically obtained flow fields were interrogated to identify the physical mechanism responsible for improvement in stall margin of a modern subsonic axial-flow compressor rotor due to the discrete skewed slots. It was found that the axial skewed slot Casing Treatment can in-crease the stall margin of subsonic compressor by repositioning of the tip clearance flow trajectory further toward the trailing of the blade passage and retarding the movement of the incoming/tip clearance flow interface toward the rotor leading edge plane.

  • Experimental and Numerical Investigation of a Subsonic Compressor With Bend Skewed Slot Casing Treatment
    Volume 6: Turbomachinery Parts A and B, 2006
    Co-Authors: Wuli Chu, Junqiang Zhu
    Abstract:

    Based on the test results of discrete axial and blade angle slot Casing Treatment, a new type of Casing Treatment was designed for a subsonic axial flow compressor rotor by optimising various geometry parameters. To obtain a wide operating range and to minimize penalties in terms of isentropic efficiency, seven compressor configurations incorporating Casing Treatments of 0%, 16.6%, 33.3%, 50%, 66.6%, 83.3% and 100% rotor exposure were experimentally investigated. The results showed that significant improvements in stall margin are possible in all exposures and insignificant isentropic efficiency sacrifices are recorded in some exposures. Nearly 21.43% stall margin improvement in terms of the corrected mass flow rate was achieved with 33.3% rotor blade tip axial chord exposure. The compressor build with 16.6% rotor exposure was the best configuration in terms of maximum isentropic efficiency gain. The second issue of the paper was to offer a contribution to the understanding of the physical mechanism by which bend skewed slot Casing Treatment improve stall margin under subsonic conditions. By applying a concept similar to “Domain Scaling” approach (as often used in multistage turbomachinery Flow-fields) to the interface between the rotor blade passage and end-wall Treatments, a time-dependent 3-dimentional numerical simulation was performed for the subsonic axial-flow compressor rotor with bend skewed slot Casing Treatment. The numerical results agreed well with experimental results. Detailed analyses of the coupled flow through bend skewed slot Casing Treatment and rotor blade passage under subsonic conditions led to some preliminary conclusions as to the flow physics involved in the stall margin improvements afforded by the use of bend skewed slot Casing Treatment.© 2006 ASME

Cui Weiwei - One of the best experts on this subject based on the ideXlab platform.

  • Investigation on axial effect of slot Casing Treatment in a transonic compressor
    Applied Thermal Engineering, 2017
    Co-Authors: Xiaoyong Zhou, Qingjun Zhao, Cui Weiwei
    Abstract:

    Abstract This paper reports the effect of the axial position of the slot Casing Treatment on the performance of transonic compressor NASA Rotor 67 by unsteady numerical simulation. The interaction of the recirculation in the slots and flow near the blade tip is analyzed to understand the flow mechanisms. The relative importance of the mechanisms of stall margin improvement due to the slot Casing Treatment is evaluated with the relative weight method. The results show that the bleeding and injecting effect caused by the recirculation is the most important factor that affects the blockage in the blade tip region, which determines the stall margin improvement. When the slots cover the initial position of the tip leakage vortex (TLV) and the boundary layer separation zone downstream the shock, the recirculation is stronger due to the larger pressure difference between the front and rear part of the slots. Consequently, the slot Casing Treatment can reduce the blockage near the Casing more effectively, which results in a larger stall margin improvement. Shifting the slots upstream or downstream will reduce the driving force for the recirculation and the effect extent on the low energy fluid of the slots, which decreases the stall margin improvement.

Bo Liu - One of the best experts on this subject based on the ideXlab platform.

  • investigation of the Casing groove location effect for a large tip clearance in a counter rotating axial flow compressor
    Aerospace Science and Technology, 2020
    Co-Authors: Xiaochen Mao, Bo Liu
    Abstract:

    Abstract In the present work, the location effect of single grooved Casing Treatment (CT) on the compressor performance and flow stability are numerically studied at a large tip clearance in a two-stage counter-rotating axial flow compressor. The results show that the first stall stage is changed from the rear rotor (R2) to the front rotor (R1) as the tip clearance is increased from the normal design tip clearance (τ) to a large tip clearance of 2τ. The compressor stability can only be improved by the CT schemes in R1 without obvious change of compressor efficiency, while the compressor efficiency at near stall point can be increased remarkably for the effective CT configurations in R2 without stall margin improvement (SMI). The stall inception type may be changed for the least effective CT configuration in R1 due to the drastic change of flow structure of the tip leakage flow (TLF) released from near the blade leading edge. Detailed analysis of TLF structure shows that it is advisable to improve the compressor flow stability by controlling the TLF part which is released from the blade chord range away from the blade leading edge. After the application of effective CT schemes, the tip flow field is improved in the corresponding rotor and the interface is pushed further downwards to a different extent resulting in the reduction of the TLF intensity and loss generation.

  • the impact of Casing groove location on the flow instability in a counter rotating axial flow compressor
    Aerospace Science and Technology, 2018
    Co-Authors: Xiaochen Mao, Bo Liu, Tianquan Tang, Hang Zhao
    Abstract:

    Abstract To make up the lack of the experimental and numerical investigations about the grooved Casing Treatment (CT) applied in counter-rotating axial flow compressors (CRAC), the effects of circumferential single grooved CT on the stability enhancement were investigated in the rear rotor of a low-speed CRAC with numerical simulations. The main purpose was to gain a better understanding of the application principle of Casing groove and the associated control mechanisms in the CRAC. Parametric studies show that the optimal position of the groove should be located near the blade leading edge in terms of stall margin improvement (SMI) and efficiency enhancement at the near stall condition. Due to the impact of Casing groove on tip leakage flow (TLF), the blade tip unloading effect, redirection effect and the compound effect of suction–injection are all beneficial to the SMI. Detailed observation of flow structures illustrates that it is more effective to improve flow stability by controlling the critical TLF released from about mid-chord and the stall inception process may be probably changed due to the direct effect of groove on the main TLF released near the blade leading edge. Additionally, the effects that the groove has on rotor outflow blockage, backward axial momentum flux and TLF momentum perpendicular to the blade tip camber inside the tip gap are also studied in the paper.

  • numerical analysis of the circumferential grooves Casing Treatment in a counter rotating axial flow compressor
    Applied Thermal Engineering, 2018
    Co-Authors: Xiaochen Mao, Bo Liu, Hang Zhao
    Abstract:

    Abstract The impact of the circumferential grooves Casing Treatment over the rear rotor (R2) in a counter-rotating axial flow compressor has been investigated based on numerical simulations. The main purpose is to understand the effects of grooved Casing Treatment on the unsteady flow behaviors and the corresponding mechanisms of the stability enhancement in the compressor. The results show that the interface between incoming main flow and tip leakage flow in R2 is pushed downstream obviously and the flow stability is enhanced with grooved Casing Treatment. The compressor performance at near stall condition is also improved remarkably. The blade loading below the grooves, the incidence angle near the blade tip and the backward axial momentum flux injected into main flow passage through the tip gap are all reduced, which is beneficial to the stall margin improvement. Frequency analysis near the blade tip of R2 indicates that the oscillations with lower frequency are suppressed by the Casing grooves and the fluctuating intensity decreases, which also contributes for the enhancement of flow stability. Detailed observation of tip leakage flow structures illustrates that it is more effective to improve the flow stability by controlling the tip leakage flow released from near mid-chord.