Abstract
The present study focuses on the influence of the swirling flows on flow behaviors and performance of a radial-flow turbocharger turbine under pulsating inflow condition. To characterize the effects of swirling flow, three sets of simulations of the turbine were carried out, which are an unsteady simulation under pulsating swirling inflow, an unsteady simulation under equivalent pulsating uniform inflow, and quasi-steady simulations under uniform inflow. Results proved that swirling flow has a considerable negative influence on turbine instantaneous performance and lead to 2.5% cycle-averaged efficiency reduction under pulsating flow condition. Swirling inflow would lead to significant losses in both the volute and the rotor, while the pulsating inflow leads to higher losses in the rotor and shows little influence on the losses in the volute. The instantaneous efficiency reduction of the turbine could be correlated with the time-varying inlet swirl strength. Under the influence of unsteady inlet swirls, the volute flow field is highly distorted and the free vortex relation is no longer valid. The swirling flow has strong interactions with the wake flow of the volute tongue, leading to additional losses. Relative flow angle at rotor inlet is remarkably reduced and its distribution is significantly distorted. Strong separation flows and passage vortices would appear in the rotor because of the swirling inflow, leading to inferior rotor performance.
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Abbreviations
- CFD:
-
Computational fluids dynamics
- HPT:
-
High-pressure turbine
- ICE:
-
Internal combustion engine
- LPT:
-
Low-pressure turbine
- MFP:
-
Mass flow parameter
- SST:
-
Shear Stress Transport
- VR:
-
Velocity ratio
- C :
-
Absolute velocity/m·s−1
- c p :
-
Specific heat capacity at constant pressure/J·(kg·K)−1
- K :
-
Total pressure loss coefficient
- L :
-
Loss
- m :
-
Mass flow rate/kg·s−1
- p :
-
Pressure/Pa
- T :
-
Temperature/K
- t :
-
Time/s
- M :
-
Torque/N·m
- U :
-
Blade tip peripheral speed/m·s−1
- W :
-
Work/J
- β :
-
Relative flow angle/(°)
- γ :
-
Ratio of specific heat capacities
- η :
-
Efficiency
- π :
-
Expansion ratio
- θ :
-
Azimuth angle/(°)
- ρ :
-
Density/kg·m−3
- τ 87 :
-
Average swirl angle at 0.87R/(°)
- ω :
-
Angular velocity/rad·s−1
- 0:
-
total state
- 1:
-
LPT inlet
- 2:
-
LPT volute outlet/rotor inlet
- 3:
-
LPT outlet
- a:
-
axial
- isen:
-
isentropic
- r:
-
rotor
- v:
-
volute
- θ :
-
circumferential
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Acknowledgments
The authors would like to thank the foundation of Science and Technology on Diesel Engine Turbocharging Laboratory (No.6142212190101) and Young Elite Scientists Sponsorship Program by CAST (2021QNRC001) for the supports.
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Ding, Z., Wang, C., Zhang, J. et al. Characterization of Swirling Inflow Effects on Turbine Performance under Pulsating Flows. J. Therm. Sci. 31, 1734–1744 (2022). https://doi.org/10.1007/s11630-022-1671-0
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DOI: https://doi.org/10.1007/s11630-022-1671-0