Unsteady Investigation on Tip Flow Field and Rotating Stall in Counter-Rotating Axial Compressor

Gao, Limin; Li, Ruiyu; Fang, Miao; Yuan-hu, Cai

doi:10.1115/1.4029101

Cited by 39 publications

(24 citation statements)

References 5 publications

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“…They found that the first stall stage of counter-rotating compressor varies with the tip clearance size increases. An unsteady numerical investigation on tip flow and rotating stall in a CRAC by Gao et al 22 showed that a double-leakage flow 8 (the passage of tip clearance fluid through the neighboring tip clearance gap) plays an important role in the unsteadiness of CRAC's unsteady flow field. The frequency analysis also captured the transition of the second harmonic frequency, which can be used as stall inception signal.…”

Section: Introductionmentioning

confidence: 99%

Numerical investigation of the unsteady flow behaviors in a counter-rotating axial compressor

Mao

Liu

2016

Proceedings of the Institution of Mechanical Engineers, Part A:

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Unsteady numerical simulations of a counter-rotating axial compressor are performed to investigate the unsteady effects of rotor-rotor interaction process and the tip flow unsteady behavior near the stall operating condition. The results show that potential effects from the rear rotor have a more pronounced influence on the front rotor. Because of the interaction between the two rotors and the unsteady flow behaviors, the strongest fluctuant regions are different for the two rotors. Additionally, the oscillation on the pressure side is generally much stronger than that on the suction side. Frequency analyses show that self-unsteadiness occurs with the frequency of 0.76 blade passing frequency due to the impingement of the tip leakage flow on the pressure side near leading edge of the adjacent blade. An interesting phenomenon, i.e., the emergence of a local high pressure spot, is observed in the tip region. As a whole, it is concluded that there are two key effects of the emergence of the local high pressure zone in the tip region: (a) more leading edge spillage of tip leakage flow and increasing the risk to trigger stall; and (b) a decrease in blockage associated with doubleleakage of tip clearance flow within the influenced region of the local high pressure zone.

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Section: Introductionmentioning

confidence: 99%

Numerical investigation of the unsteady flow behaviors in a counter-rotating axial compressor

Mao

Liu

2016

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…Tip leakage vortex plays a key role in stall inception, which has become a consensus. As found in many researches [15,[21][22][23], unsteady fluctuations are existed in the tip leakage flow field of most fans/compressors under the near-stall states, tip leakage vortex breaks under certain conditions, but disagreements are still appeared in mechanisms of unsteady flow phenomenon in tip regions. As demonstrated in numerical simulation of unsteady flow by Hu [24], weak unsteady character is stayed in the near-stall points of the low speed fan, which is basically consistent with the result obtained from the steady calculation.…”

Section: Effect Of Speed Ratio On Characteristics Of Tip Clearance Flmentioning

confidence: 95%

Effect of counter-rotating fan’s speed matching on stall inception and characteristics of tip clearance flow

Luan¹,

Chen²,

Weng³

et al. 2017

J. vibroeng.

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In order to study the effect of speed matching on behavior of tip clearance flow and its possible link to stall inception in counter-rotating fan, the Reynolds-averaged Navier-Stokes equations are solved by the numerical method in conjunction with a SST turbulence model, the effect of speed matching on performance and stability margin are investigated, so are the difference of the tip clearance flow in different speed matching. Furthermore, the effect of speed matching on behavior of tip clearance flow and its possible link to stall inception are investigated. Research results show that: when the rotational speed of Rotor 2 is less than that of Rotor 1, with the decrease of rotational speed of Rotor 2 has no notable effect on tip clearance flow fields of the two rotors, therefore offset of stalling boundary is minor and strong blockage effect is observed in Rotor 1; when the rotational speed of Rotor 1 is less than that of Rotor 2, decrease of rotational speed of Rotor 1 show significant effect on the two rotors, which leads to major offset of stalling boundary, tip leakage flow performance of Rotor 1 improved, while that of Rotor 2 weakened and large blockage area occurs. By comparison, speed variation of Rotor 1 has more effect on stalling boundary of counter-rotating fan.

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“…For example, a circumferential groove with its leading edge positioned at 20% tip axial chord length downstream of the blade leading edge is named G2. Previous research on this compressor has indicated that the flow fields in the tip region of R2 are responsible for the spike-type flow instability of the CRAC [35,37,38]. Therefore, different circumferential single grooves over the blade tip of R2 were numerically investigated in the current paper.…”

Section: Compressor Geometry and Ct Designmentioning

confidence: 99%

“…Endeavors to gain further insights into the flow physics in CRAC have been conducted on the important factors, including axial spacing between two rotors, unsteady effects, inlet distortion, etc. [30][31][32][33][34][35][36][37][38]. Compared with a conventional compressor stage, it was found that there are many new characteristics and unique flow phenomena in CRAC.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation for the Impact of Single Groove on the Stall Margin Improvement and the Unsteadiness of Tip Leakage Flow in a Counter-Rotating Axial Flow Compressor

Mao¹,

Liu²,

Zhao³

2017

Energies

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Abstract:A low-speed counter-rotating axial flow compressor (CRAC) with single circumferential grooved casing treatment (CT) was investigated numerically. Both steady and time-accurate numerical calculations were performed to study the effects of the single grooved CTs over the rear rotor on the stability enhancement and the unsteadiness of tip leakage flow (TLF) in the CRAC. Parametric studies indicate that the best position of the single groove should be located near about 20% axial tip chord in terms of the stall margin improvement (SMI). The coincidence of the effective CT locations and the high fluctuating region on blade pressure surface in the smooth wall case shows that the unsteadiness of TLF plays an important role in the stall inception process. Frequency analysis for the static pressure signals near the blade tip shows that both the disappearance of the low frequency components and the suppression of unsteady TLF are beneficial to the SMI. Detailed observation of the flow structures illustrates that the action of the grooves on the different parts of TLF is responsible for the difference of SMI in the CTs. It is more effective to improve the flow stability by controlling the critical TLF released from near the mid-chord.

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Unsteady Investigation on Tip Flow Field and Rotating Stall in Counter-Rotating Axial Compressor

Cited by 39 publications

References 5 publications

Numerical investigation of the unsteady flow behaviors in a counter-rotating axial compressor

Numerical investigation of the unsteady flow behaviors in a counter-rotating axial compressor

Effect of counter-rotating fan’s speed matching on stall inception and characteristics of tip clearance flow

Numerical Investigation for the Impact of Single Groove on the Stall Margin Improvement and the Unsteadiness of Tip Leakage Flow in a Counter-Rotating Axial Flow Compressor

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