Effect of Incidence Angle on Entropy Generation in the Boundary Layers on the Blade Suction Surface in a Compressor Cascade

Shi, Lei; Ma, Hongwei

doi:10.3390/e21111049

Cited by 12 publications

(5 citation statements)

References 35 publications

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“…They found that as the flow incidence angle increased, the secondary flow loss and boundary layer losses in the compressor at the leading edge increased. This finding was further investigated by Shi and Ma through 9 experimental testing and EGR analyses. Using a numerical EGR analysis, Juan and Van 18 investigated the effects of bypass grooves on the performance of a mixed-flow compressor.…”

Section: Introductionmentioning

confidence: 86%

“…Herving and Koke 26 modeled the fluctuating term using the k-ε turbulence model relationships. Using the Fourier heat transfer law (equation ( 8)), the final form of equation ( 7) can be written as equation (9), which is used to measure the field of the EGR.…”

Section: Entropy Generation Ratementioning

confidence: 99%

“…Internal losses are defined as local losses that affect both the efficiency and pressure ratio; external losses result in an efficiency drop. Internal losses include incidence, 9 entrance diffusion, 10 blade loading, 10,11 skin friction, 11 shock waves, 10,12 wake, 13 tip leakage, 14 and distortion losses. 15 External losses include recirculation, disk friction, and leakage.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 86%

Section: Entropy Generation Ratementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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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“…The uncertainty of the instantaneous PIV results is about 3.5% of the maximum velocity. For more information about the uncertainty, one can refer to [ 23 , 24 ], in which the same PIV system was adopted.…”

Section: Methodsmentioning

confidence: 99%

Experimental Investigation of the Effect of Purge Flow and Main Flow Interaction in a Low-Speed Turbine Cascade Passage

Zhao

2020

Entropy

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In order to protect the vulnerable turbine components from extreme high temperature, coolant flow is introduced from the compressor to the disk cavity, inevitably interacting with the main flow. This paper describes an experimental investigation of the interaction between the main flow and the purge flow in a low-speed turbine cascade with three purge flow rates, Cm = 0, Cm = 1%, and Cm = 2%. In order to study the effect of the interaction between the main flow and the purge flow on the secondary flows, a Rortex method developed by Liu Chaoquan is introduced to identify the vortex in the flow field. In the meantime, a method to calculate the mean entropy production rate based on the particle image velocimetry (PIV) result is adopted to investigate the flow loss. The PIV result indicates that the purge flow has a prominent impact on the flow field of the cascade passage, changing the velocity distribution that induces a local blockage area. The results of vortex identification show that the purge flow promotes the generation of the passage vortex near the suction side. In addition, the purge flow makes the passage vortex migrate to the tip wall direction, enlarging the region affected by the secondary flow. The mean entropy production (MEP) result shows that the flow loss is mainly caused by the passage vortex. The coincidence of the high-MEP region and the location of the passage vortex indicates that the purge flow increases the secondary flow loss by affecting the formation and the migration of the passage vortex.

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“…Unlike the circular leading edge, which is widely used, Walraevens and Cumpsty confirmed that the boundary layer behind the elliptic leading edge was healthier, and they indicated that the difference was due to the laminar separation bubbles caused by the velocity spike around the leading edge [2]. With the deepening of the research, Shi et al indicated that the entire integral entropy generation in the boundary layer increased sharply when the laminar separation bubble moved upstream to the leading edge [3], and Lambert et al observed that the size of the laminar separation bubble increased with a larger incidence angle [4]. Given the importance of a leading edge spike, Goodhand et al quantified the spike intensity [5], and they presented a continuous-curvature leading edge to eliminate a spike at the designed incidence angle.…”

Section: Introductionmentioning

confidence: 99%

Velocity Increment on Incidence Angle near the Leading Edge of the Compressor Cascade

Liu

et al. 2023

Aerospace

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The geometry of a compressor leading edge has an important effect on the aerodynamic performance at an off-designed incidence angle. The current geometric design methods of the leading edge are usually developed based on the flow characteristics at the designed incidence angle. However, few research focuses on the quantitative rules of the leading edge flow characteristics at the off-designed incidence angle in a compressor cascade. This situation restricts the further optimization and development of the leading edge geometry design method. In this paper, starting from the research of a potential cascade theory, the singularity point, where the surface velocity approaches infinity in the leading edge region, is eliminated by applying the characteristic that the ratio of the velocity increasement on the incidence angle in the plate cascade and the isolated plate flow is finite. Secondly, the equivalent pitch lengths based on 1/cos(β) and VI caused by a diffuser deceleration in the cascade passage were employed to correct the effect of the stagger angle. Finally, by introducing the isolated flow around the thick airfoil and considering the influence of the camber line geometry, a model of the variation of the surface velocity near the leading edge under the off-designed incidence angle, named the velocity increment on incidence angle, is derived from any compressor cascade. Hence, the relation between the off-designed incidence angle and the designed incidence angle of the surface velocity in a cascade blade is established, and it depends only on the geometrical parameters. Through a verification using numerical calculations and experimental measurement, the explicit formula for the velocity increment on incidence angle proposed in this paper has high precision near the leading edge.

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Effect of Incidence Angle on Entropy Generation in the Boundary Layers on the Blade Suction Surface in a Compressor Cascade

Cited by 12 publications

References 35 publications

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

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

Experimental Investigation of the Effect of Purge Flow and Main Flow Interaction in a Low-Speed Turbine Cascade Passage

Velocity Increment on Incidence Angle near the Leading Edge of the Compressor Cascade

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