Mechanism of Blockage Generation in Transonic Centrifugal Compressor at Design and Off-Design Conditions

Kaneko, Masanao; Tsujita, Hoshio

doi:10.1115/gt2015-43126

Cited by 3 publications

(2 citation statements)

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“…In the present study, the tip Mach number is less than one, and without considering the shockwave effects on the TLV, which is different from the situation in transonic compressor. 31 By analyzing the TLV trajectory and mainflow/TLF interface at different operating points, we observe that the TLV trajectory and mainflow/TLF interface move away from the suction side, and they are shifted towards upstream as the mass flow rate decreases. At the nearstall condition (Q m ¼ 3.6 kg/s), the mainflow/TLF interface is close to the leading edge of the adjacent blade.…”

Section: Tlf Comparisons At Different Operating Conditionsmentioning

confidence: 91%

Numerical investigations on tip leakage flow characteristics and vortex trajectory prediction model in centrifugal compressor

Zhao

Wang

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part A:

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To better understand the characteristics of tip leakage flow and interpret the correlation between flow instability and tip leakage flow, the flow in the tip region of a centrifugal impeller is investigated by using the Reynolds averaged Navier-Stokes solver technique. With the decrease of mass flow rate, both the tip leakage vortex trajectory and the mainflow/ tip leakage flow interface are shifted towards upstream. The mainflow/tip leakage flow interface finally reaches the leading edge of main blade at the near-stall condition. A prediction model is proposed to track the tip leakage vortex trajectory. The blade loading at blade tip and the averaged streamwise velocity of main flow within tip clearance height are adopted to determine the tip leakage vortex trajectory in the proposed model. The coefficient k in Chen's model is found to be not a constant. Actually, it is correlated with h/b (the ratio of blade tip clearance height to blade tip thickness), because h/b will significantly influence the flow structure across the tip clearance. The effectiveness of the proposed prediction model is further demonstrated by tracking the tip leakage vortex trajectories in another three centrifugal impellers characterized with different h/b (s).

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Section: Tlf Comparisons At Different Operating Conditionsmentioning

confidence: 91%

Numerical investigations on tip leakage flow characteristics and vortex trajectory prediction model in centrifugal compressor

Zhao

Wang

et al. 2016

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…The gradual streamwise growth of the EGR near the hub in the leading-edge boundary layer was due to the developed tip vortices at higher spans. These tip vortices caused blockages near the shroud 49 and applied pressure to the passing streams near the hub wall. The EGR near the shroud wall tended to decline in both conditions due to the development of vortices.…”

Section: Resultsmentioning

confidence: 99%

Entropy generation rate analysis of turbocharger radial flow compressor in range from surge to choke

Altafi,

Mojaddam,

Bastankhah

2023

Proceedings of the Institution of Mechanical Engineers, Part A:

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This study compares the local losses of a radial compressor in the range from surge to choke considering shock phenomena, boundary layer separation, and mixing mechanisms. For this purpose, formulation of the local entropy generation rate (EGR) is added to the computational fluid dynamics (CFD) solver, which models the turbulent flow field of the compressor through the RANS approach. For validation, the numerical pressure rise curve of the compressor is compared with the experimental data. The results indicate that at the design point, the impeller, diffuser, and the volute account for approximately 50.8%, 30.0%, and 12.3% of the EGR, respectively, with approximately 5% in the impeller backspace, 1% in the diffuser cavity, and less than 0.5% in the inlet duct. Approaching the surge condition, local losses due to mixing and shock waves decline while boundary layer losses increase. Based on comprehensive analysis of the leading-edge boundary layer, the largest dead-air zone is found at the design point, resulting in a lower diffusion entrance loss and a higher mixing loss. Furthermore, the EGR variation in the diffuser channel is investigated by shedding light on mixing dynamics and classification of the channel flow regime into three different zones based on mixing ratio (MR). The outcomes show that the flow regime tends to mix more quickly at a higher MR, resulting in a slight decrease in EGR, which benefits compressor performance. We demonstrate that the mixing rate of flow regimes decreases in both the leading-edge boundary layer and the radial diffuser approaching the surge margin.

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Influences of tip leakage flows on flow field at design condition in transonic centrifugal compressor with splitter blade

Kaneko¹,

Tsujita²

2016

Transactions of the JSME (In Japanese)

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A tip leakage flow is well known to have predominant influence on a loss generation in a compressor. An impeller for a transonic centrifugal compressor is generally composed of the main and the splitter blades to gain the choke flow rate. In this study, in order to clarify the individual influence of the tip leakage flows from the main and the splitter blades on the flow behavior in the transonic centrifugal compressor at design condition, the flows in the compressor at four conditions prescribed by the presence or the absence of the tip clearances of the main and the splitter blades were analyzed numerically. The computed results clarified a series of interactive influences of the tip leakage vortices on the flow field as follows. The tip leakage vortex from the leading edge of the main blade increased the incidence angle for the splitter blade by its blockage effect. The increased incidence angle generated the tip leakage vortex from the leading edge of the splitter blade and intensified the acceleration of the flow over the suction surface of the splitter blade. The accelerated flow produced the negative blade loading of the adjacent main blade by reducing the static pressure on the pressure surface of the main blade, which generated the tip leakage vortex appearing from the pressure side of the main blade. The tip leakage vortex from the leading edge of the splitter blade reduced the flow acceleration on the suction surface of the splitter blade by its blockage effect. As a consequence it strongly contributed to the reduction of the loss generation by suppressing the formation of the shock wave on the suction surface of the splitter blade and by decreasing the negative blade loading of the main blade.

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Mechanism of Blockage Generation in Transonic Centrifugal Compressor at Design and Off-Design Conditions

Cited by 3 publications

References 0 publications

Numerical investigations on tip leakage flow characteristics and vortex trajectory prediction model in centrifugal compressor

Numerical investigations on tip leakage flow characteristics and vortex trajectory prediction model in centrifugal compressor

Entropy generation rate analysis of turbocharger radial flow compressor in range from surge to choke

Influences of tip leakage flows on flow field at design condition in transonic centrifugal compressor with splitter blade

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