Unsteady performance of a mixed-flow turbine with nozzled twin-entry volute confronted by pulsating incoming flow

Xue, Yingxian; Yang, Mingyang; Martinez-Botas, Ricardo; Yang, Bijie; Deng, Kangyao

doi:10.1016/j.ast.2019.105485

Cited by 16 publications

(4 citation statements)

References 25 publications

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“…Indeed, for the lowest engine speed of 950 rpm the mass flow rate corresponding to the pulsating flow is about 1.27 times that of steady simulation and the average value of the power obtained from pulsating flows is about 1.36 times that from the steady flow simulation. Finally, the total-to-static isentropic efficiency corresponding to the pulsating flows reaches a value about 1.19 times that from the steady simulation, Xu et al [18] found that the cycle-average efficiency at St =0.522 is about 3.4% higher than that of quasi-steady condition. For other engine speeds .i.e.…”

Section: Fig 17swallowing Capacity Of Twin-entry Radial Turbinementioning

confidence: 90%

“…Baines and Yeo [12,13] extended the measurements of Dale and Watson [10] by focusing on the flow field through a twinentry nozzle-less turbine and concluded that the flow incidence at rotor entry varies from −60 -30 deg for extreme unequal admission conditions (one entry fully closed). Xue et al [18] investigated numerically with experimental validation the mixed-flow turbine with nozzled twin-entry volute at pulsating conditions with different Strouhal numbers (flow frequency). The results confirm that that the unsteadiness of turbine performance is directly proportional to the Strouhal number.…”

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confidence: 99%

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Matching of Radial Inflow Turbines with Internal Combustion Engines Considering Pulsating Flows

CERDOUN,

Ghenaiet,

Ferrara

2023

Preprint

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This paper investigates numerically the effects of pulsating exhaust gases on the operations of radial inflow turbines and their matching with internal combustion engines at full-load conditions. Both single- and twin-entry radial turbines are considered and the transient behaviors are analyzed by combining the CFD and analytical models. As results, the unsteady performances are shown to deviate noticeably from the steady state due to high levels of unsteadiness of the inlet conditions. A typical hysteresis-loop relating the effect of gas filling-emptying inside the volute is well depicted. Unsteady performance of the twin-entry radial turbine depicts that the of hysteresis-loop is wide due to large volute volume whereas the hysteresis-loop of single-entry turbine seems reducingas the amplitude of pressure pulse reduces. For the compressor side of the twin-entry radial turbine, and depending on the engine speed, the average values of unsteady performances exhibit deviations up to 9% in pressure ratio and 7.8% in airflow swallowing capacity, in contrast to the single-entry radial turbine these deviations are lesser about 4 and 4.9%, respectively. These differences could be related to the two sides of volute which are source of hysteresis and flow interaction.

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Section: Fig 17swallowing Capacity Of Twin-entry Radial Turbinementioning

confidence: 90%

mentioning

confidence: 99%

Matching of Radial Inflow Turbines with Internal Combustion Engines Considering Pulsating Flows

CERDOUN,

Ghenaiet,

Ferrara

2023

Preprint

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“…Studies on the twin-entry turbines with meridian symmetric volutes show that the swallowing capacity of the turbine under partial admissions is almost similar, but the efficiency is notably different. [8][9][10][11] The peak efficiency is different by about 2% when the flow is fed to the different limbs. Moreover, the lowest efficiency is reached at partial admission when the limb near the shroud is totally blocked.…”

Section: Introductionmentioning

confidence: 99%

A comparison study of loss generation between twin-entry and double-entry volutes of nozzled mixed-flow turbines

Yang,

Xue,

et al. 2023

International Journal of Engine Research

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Turbochargers whose turbines contain two-entry volutes are advantageous as they help to improve the low-end torque and transient performance of internal combustion engines. Two types of two-entry turbines are applied currently in turbocharging, which are the twin-entry turbine (TE) and the double-entry turbine (DE). To develop more efficient turbocharged engines, a further understanding of the performance characteristics and loss mechanisms of two types of two-entry turbines is needed. However, few investigations have been carried out to directly compare these two types of turbines. Through an experimentally validated numerical method, this paper compares the performance and detailed flow mechanism of twin/double-entry turbines with the same nozzled mixed-flow rotor. The 3D simulation is validated against the measured performance as well as the flow field carried out on test rigs. Results show that the performance of the double-entry turbine is notably superior over that of the twin-entry counterpart although their peak swallowing capacities and efficiencies are at a similar level. In particular, the efficiency and swallowing capacity deteriorate more gently for the double-entry turbine as operational condition deviates from full admission. It was revealed via the loss breakdown of turbine components that, the volute and the nozzle are the main contributors to the performance discrepancy between the two turbines. Specifically, the loss in the twin-entry volute is higher than that of the double-entry one, especially in the case of partial admissions. Flow analysis shows that the flow is mixed strongly in the vicinity of the limb divider of the twin-entry volute in the whole circumference, while it only concentrates in the vicinity of the tongues for the double-entry turbine. Therefore, a higher entropy-rise is generated in the twin-entry volute. Moreover, the mixing flow attenuates the flow distortion in the nozzle and produces more uniform entropy rise in the nozzle for the twin-entry configuration. On the other hand, flow distortion is well preserved in nozzle for the double-entry turbine, thus regions with high entropy-rise appear in a portion of nozzle passages. Consequently, a higher loss is produced in the volute and the nozzle for the twin-entry turbine. This paper provides knowledge of performance characteristics of two two-entry turbines and sheds light on the performance improvement of two-entry turbines.

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“…Also, some authors have shown very interesting results regarding the effect of high-amplitude pulses inside the turbine in its efficiency, such as Xue et al [42]: these effects may be included in simplified models for simplified one-dimensional simulations.…”

Section: Introductionmentioning

confidence: 99%

Using a CFD analysis of the flow capacity in a twin-entry turbine to develop a simplified physics-based model

Galindo

Serrano

Medina

2021

Aerospace Science and Technology

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Unsteady performance of a mixed-flow turbine with nozzled twin-entry volute confronted by pulsating incoming flow

Cited by 16 publications

References 25 publications

Matching of Radial Inflow Turbines with Internal Combustion Engines Considering Pulsating Flows

Matching of Radial Inflow Turbines with Internal Combustion Engines Considering Pulsating Flows

A comparison study of loss generation between twin-entry and double-entry volutes of nozzled mixed-flow turbines

Using a CFD analysis of the flow capacity in a twin-entry turbine to develop a simplified physics-based model

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