Investigations on the Effects of Inflow Condition and Tip Clearance Size to the Performance of a Compressor Rotor

Zhang, Chenkai; Hu, Jun; Wang, Zhiqiang

doi:10.1115/1.4027906

Cited by 13 publications

(7 citation statements)

References 23 publications

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“…A multi-block O4H-type structured mesh is generated in the computational domain, with an O-type mesh around the blade and H-type mesh in the remaining regions. Previous investigations show that 17 grid points in tip clearance can well-predict the local flow fields (Zhang et al , 2014). In this work, the mesh consists of 17 grid points in the tip clearance to model the local flows.…”

Section: Computational Techniques and Cfd Validationsmentioning

confidence: 99%

“…In the investigations conducted by Zhang et al (2014), the effects of three upstream IBL thicknesses (0, 10 and 20 per cent IBL) on the rotor performance have been studied. The results indicate that a 10 per cent IBL thickness has only a slight impact on the peak efficiency, while more than 20 per cent IBL thickness reduces the peak efficiency significantly.…”

Section: Problem Descriptionsmentioning

confidence: 99%

“…The investigations conducted by Brandt et al (2002) for an isolated compressor rotor showed that the increment of the upstream boundary layer thickness would lead to the roll-up of the clearance vortex to move toward the leading edge, which could cause more aerodynamic losses in the end-wall region. Moreover, Zhang et al (2014) conducted a numerical study on the effects of different IBL thicknesses on the compressor rotor performance. When the upstream boundary layer thickness was increased at the design working condition, both the starting point of leakage vortex and the interface of leakage and main flows would move forward, leading to decreases of efficiency and pressure ratio.…”

Section: Introductionmentioning

confidence: 99%

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Analysis and application of shroud wall optimization to an axial compressor with upstream boundary layer to improve aerodynamic performance

Pan

et al. 2019

HFF

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Purpose For an axial-flow compressor rotor, the upstream inflow conditions will vary as the aircraft faces harsh flight conditions (such as taking off, landing or maneuvering) or the whole compressor operates at off-design conditions. With the increase of upstream boundary layer thickness, the rotor blade tip will be loaded and the increased blade load will deteriorate the shock/boundary layer interaction and tip leakage flows, resulting in high aerodynamic losses in the tip region. The purpose of this paper is to achieve a better flow control for tip secondary flows and provide a probable design strategy for high-load compressors to tolerate complex upstream inflow conditions. Design/methodology/approach This paper presents an analysis and application of shroud wall optimization to a typical transonic axial-flow compressor rotor by considering the inlet boundary layer (IBL). The design variables are selected to shape the shroud wall profile at the tip region with the purpose of controlling the tip leakage loss and the shock/boundary layer interaction loss. The objectives are to improve the compressor efficiency at the inlet-boundary-layer condition while keeping its aerodynamic performance at the uniform condition. Findings After the optimization of shroud wall contour, aerodynamic benefits are achieved mainly on two aspects. On the one hand, the shroud wall optimization has reduced the intensity of the tip leakage flow and the interaction between the leakage and main flows, thereby decreasing the leakage loss. On the other hand, the optimized shroud design changes the shock structure and redistributes the shock intensity in the spanwise direction, especially weakening the shock near the tip. In this situation, the shock/boundary layer interaction and the associated flow separations and wakes are also eliminated. On the whole, at the inlet-boundary-layer condition, the compressor with optimized shroud design has achieved a 0.8 per cent improvement of peak efficiency over that with baseline shroud design without sacrificing the total pressure ratio. Moreover, the re-designed compressor also maintains the aerodynamic performance at the uniform condition. The results indicate that the shroud wall profile has significant influences on the rotor tip losses and could be properly designed to enhance the compressor aerodynamic performance against the negative impacts of the IBL. Originality/value The originality of this paper lies in developing a shroud wall contour optimization design strategy to control the tip leakage loss and the shock/boundary layer interaction loss in a transonic compressor rotor. The obtained results could be beneficial for transonic compressors to tolerate the complex upstream inflow conditions.

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Section: Computational Techniques and Cfd Validationsmentioning

confidence: 99%

Section: Problem Descriptionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Analysis and application of shroud wall optimization to an axial compressor with upstream boundary layer to improve aerodynamic performance

Pan

et al. 2019

HFF

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“…Deng et al 5 and Zhang et al 6,7 argued that the TLF unsteadiness was a result of a dynamic balance between the loading and unloading of the blade. Zhang et al 8 suggested that the strongest unsteadiness was located near 50% chord of the pressure surface in the tip region. Taghavi-Zenouz et al 9 suggested that the strongest unsteadiness occurred at the position where the TLF impinged on the pressure side of the adjacent blade.…”

Section: Introductionmentioning

confidence: 99%

Investigation of tip leakage flow unsteadiness and rotating instability in a centrifugal compressor impeller

Wang

Yang

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part D:

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A phenomenon called rotating instability was rarely reported in a centrifugal compressor, although some associated discussions can be found in axial compressors. This paper presents a numerical investigation on the unsteadiness of the tip leakage flow and rotating instability in an isolated centrifugal compressor impeller. A three-dimensional, unsteady full annuls simulation is performed under three different operating conditions. The tip leakage flow unsteadiness at the impeller inlet and inside the impeller passage is detected by the pressure fluctuation. During the throttling process, the temporal and spatial propagation characteristic of the tip leakage flow unsteadiness under the near stall operating condition is revealed based on the wavelet analysis, Fourier transform, and dynamic mode decomposition. Furthermore, the relationship between the tip leakage flow unsteadiness and the rotating instability is also discussed. The results show that the pressure fluctuation mainly concentrates in the tip region at the near stall operating condition, which indicates the occurrence and circumferential propagation of tip leakage flow unsteadiness. The circumferential propagation of the tip leakage flow unsteadiness induces a significant circumferential rotating pressure wave with a wave number of 9 and approximately 48.2% of the rotational speed of the impeller. The characteristic frequency of the tip leakage flow unsteadiness agrees well with the dominant mode frequency of rotating instability. Therefore, the tip leakage flow unsteadiness is assumed to be responsible for the rotating instability. During the throttling process, the formation and development of the rotating instability at near stall operating condition can be divided into three stages based on signal analysis: prior to rotating instability, generation and development, and rotating instability.

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“…It was shown that the stall margin for the increased tip gap with casing treatment is comparable to that of the nominal tip gap without casing treatment. A numerical study of the effects of tip clearance on the endwall flow of a low-speed compressor was conducted by Zhang et al, 6 which showed the detrimental effect of tip leakage flow on the compressor pressure ratio and efficiency. Khaleghi et al 7 studied the influence of tip injection on the stability of a high-speed compressor rotor.…”

Section: Introductionmentioning

confidence: 99%

Rotating tip clearance asymmetry and role of endwall injection in stability desensitization of a transonic fan

Khaleghi

2021

Proceedings of the Institution of Mechanical Engineers, Part A:

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The current study is aimed at understanding the effect of rotating tip clearance asymmetry on the operability and performance of a transonic compressor. Another objective of this investigation is to determine the influence of tip injection on reducing the detrimental effects of clearance asymmetry. Three dimensional unsteady Reynolds-averaged Navier–stokes simulations have been performed from choke to stall for different arrangements of non-uniform blade heights in a transonic fan. Furthermore, numerical computations have been conducted with endwall injection of air. The numerical results have been validated against experimental data. Results show that having the same mean tip clearance, the asymmetric compressor is less stable than the axisymmetric configuration. However, the peak pressure rise is found to be almost linearly correlated to the mean tip clearance for both the axisymmetric and asymmetric compressors. It is found that tip injection can desensitize the compressor to the tip clearance asymmetry. Results further reveal that tip clearance asymmetry does not change the compressor path to instability. However, endwall injection is found to be able to change the compressor stalling mode. Investigations concerning rotating non-uniformity (caused by non-uniform blade heights) are very few in open literature. The obtained results can assist in predicting the effect of rotating tip clearance asymmetry on the stability and performance of high-speed compressor rotors. Furthermore, the results uncover how tip injection can desensitize the compressor stability and affect its path into instability, which is one of the most important questions in the turbomachinery world.

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Investigations on the Effects of Inflow Condition and Tip Clearance Size to the Performance of a Compressor Rotor

Cited by 13 publications

References 23 publications

Analysis and application of shroud wall optimization to an axial compressor with upstream boundary layer to improve aerodynamic performance

Analysis and application of shroud wall optimization to an axial compressor with upstream boundary layer to improve aerodynamic performance

Investigation of tip leakage flow unsteadiness and rotating instability in a centrifugal compressor impeller

Rotating tip clearance asymmetry and role of endwall injection in stability desensitization of a transonic fan

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