Effects of Nonuniform Tip Clearance on Fan Performance and Flow Field

Chen, Yingxiu; Hou, Anping; Zhang, Mingming; Li, Jianxiong; Zhang, Simu

doi:10.1115/gt2015-42133

Cited by 10 publications

(7 citation statements)

References 6 publications

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“…In the analysis presented here, the standard k-" turbulence model was used for obtaining the turbulent viscosity. 32 The same numerical solver was used in past years 33 and has been validated with experiments. 16 The computational domain is shown in Figure 4.…”

Section: Methodsmentioning

confidence: 99%

Investigation on stall inception of axial compressor under inlet rotating distortion

Zhang

Hou

2015

Proceedings of the Institution of Mechanical Engineers, Part C:

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This paper applies a numerical approach to improve the understanding of reaction to various inflow conditions for the compressor system and the mechanism of stall inception under rotating inflow distortions. Full annulus, unsteady, three-dimensional computational fluid dynamics has been used to simulate an axial low-speed compressor operating under rotating distorted inflow conditions. The development of the flow through the rotor is then explained in terms of the redistribution of the flow field and the process of stall inception. The results suggest that the increased flow incidence close to the tip region under co-rotating inflow distortion plays an important role on the stall inception process. The presence of a strong modal wave is observed under co-rotating inflow distortions. This leads to a significant impact on the loss of stall margin, as compared with other distorted inflow conditions. There is a significant peak in the flow coefficient at stall for co-rotating inlet distortion. It can be interpreted as a resonant behavior of the compressor under a strong interaction between the flow field and inlet distortion. It indicates that the stall inception is triggered by the perturbation of the rotating distorted inflow through the long length scale disturbances.

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Section: Methodsmentioning

confidence: 99%

Investigation on stall inception of axial compressor under inlet rotating distortion

Zhang

Hou

2015

Proceedings of the Institution of Mechanical Engineers, Part C:

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“…The result is quite different from conclusions obtained by previous studies. Most of the researches on nonuniform tip clearance concluded that it led to performance degradation 6,8,15 or had little effect on compressor performance. 9–11 Further analysis is carried out below to interpret the performance improvement of the non-axisymmetric case.…”

Section: Effect Of Non-axisymmetric Clearance On Overall Performancementioning

confidence: 99%

“…In an aero-engine where tip clearance size and eccentricity change during each flight cycle and over the life of the compressor, 12 the redistribution of flow massively influences stall inception during throttling, 13,14 and the stall will occur in nonuniform clearance configurations once the minimum mass flow reaches to the local stall mass flow. 15,16…”

Section: Introductionmentioning

confidence: 99%

Some effects of non-axisymmetric tip clearance layout on axial compressor aerodynamics

Zhang

Zhuang

Teng

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part A:

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A steady and unsteady numerical research is carried out to explore some effects of a specific non-axisymmetric tip clearance layout on the overall performance and stability of an axial compressor stage. For a 4-stage low-speed research compressor (LSRC) in Shanghai Jiao Tong University (SJTU), one-eighth annulus of the inlet guide vane and the first stage rotor was modeled for this study. After the validation for the uniform tip clearance case, a specific non-axisymmetric tip clearance layout is chosen from several random cases generated by the Gaussian Probabilistic Density Function method. Unsteady time-averaged results at the near stall condition show that the chosen non-axisymmetric layout can improve the isentropic efficiency by 1.3% and extend the stall margin by 4%. Detailed analyses on flow fields are carried out to interpret the performance improvement. Due to the circumferential layout of clearance sizes, the inlet mass flow and incidence are redistributed in both the radial and circumferential directions. It leads to blade loading and tip leakage flow varying with the tip clearance size. The quantification of blockage manifests that the blockage arising from the tip leakage flow is significantly alleviated in the non-axisymmetric layout, which leads to improvements in overall performance and stall margin. Transient flow fields at the rotor tip are also analyzed at the near stall condition. For the non-axisymmetric layout, low-momentum regions originating from larger clearance sizes oscillate and develop downstream in one blade passage period.

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“…In addition, the circumferential nonuniformity of tip clearance has also been investigated. 25 According to the research of Chen et al, 26 the overall performance and flow structures are affected by two factors: clearance nonuniformity and average clearance level. There is a clear decreasing trend of the fan performance and stall margin with the increase of these two factors.…”

Section: Introductionmentioning

confidence: 99%

Attenuation of leakage flow using axially nonuniform tip clearance in high loading transonic compressor rotor

Cui

Liu

Wang

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part G:

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Several linearly nonuniform clearances have been designed to explore a novel strategy for attenuation of leakage flow in tip region of high loading transonic rotor and the effects of axially nonuniform clearance on detailed tip flow structure and stable operating range of rotor have been discussed as well. The results showed that the tip flow characteristic of rotor is affected mainly by the combined effects of two parts of low-velocity flow, which are produced by interaction of leakage flow with passage shock and boundary layer separation near suction side, respectively. However, the stall margin of rotor and isentropic efficiency near tip region is dominated significantly by the former part, and the local changes of size and shape of tip clearance have a large influence on it. Once the strength of leakage flow decreases due to clearance size variation, the boundary layer separation near suction side of blade tip worsens gradually and increases additional aerodynamic losses in passage. Both the mass flow rate and mixing losses of the tip leakage flow can be reduced due to a smaller size of clearance existing in front part of clearance of rotor with a linearly divergent clearance shape, and the area of low-velocity region near pressure side has reduced accordingly. By contrast, a linearly convergent shape of tip clearance can increase both the area of low-velocity region and the mixing loss of leakage flow as a result of a larger size of clearance existing over the front part of blade tip of rotor. Eventually, a divergent shape of tip clearance with a reasonable minimum size near leading edge of blade tip is preferred for transonic rotor in consideration of the benefit in stall margin improvement with nearly no penalty in efficiency.

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Effects of Nonuniform Tip Clearance on Fan Performance and Flow Field

Cited by 10 publications

References 6 publications

Investigation on stall inception of axial compressor under inlet rotating distortion

Investigation on stall inception of axial compressor under inlet rotating distortion

Some effects of non-axisymmetric tip clearance layout on axial compressor aerodynamics

Attenuation of leakage flow using axially nonuniform tip clearance in high loading transonic compressor rotor

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