An investigation on unsteadiness of a mixed-flow turbine under pulsating conditions

Yang, Mingyang; Deng, Kangyao; Martines-Botas, Ricardo; Zhuge, Weilin

doi:10.1016/j.enconman.2015.12.007

Cited by 27 publications

(37 citation statements)

References 19 publications

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“…Considering the assumption of two individual turbines, it is now possible to express the effective equivalent nozzle area for each entry, as shown in Equation (8). (3,4) represents the pressure in the space between stator and rotor, estimated using Equation (9) with d j i as a fitting constant [30].…”

Section: Reduced Mass Flow Fittingmentioning

confidence: 99%

“…Equation 8is then used to fit the values for a j i , b j i , c j i , and d j i coefficients for the whole turbine map of each entry with a least square method, which minimizes the root mean square error between the modeled and experimental values. By this, the coefficient values of Equation (8) are obtained, and these values for each turbine entry of the turbocharger T#1TE and T#2DV are plotted in Figure 11 versus the corresponding MFR. The analysis of individual map fitting coefficients of both entries of two turbochargers are detailed in Section 3.3 to obtain some physical trends.…”

Section: Dual-volute Turbinementioning

confidence: 99%

“…Nevertheless, a turbocharger turbine always confronts high unsteadiness of flows coming from the reciprocating internal combustion engine [8]. In recent years, automotive OEMs are seeing much interest in using the double entry turbines, especially for four cylinders turbocharged petrol engines with wide valves overlap period in their timing diagram or in six-cylinder compression ignition engines [9].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A Robust Adiabatic Model for a Quasi-Steady Prediction of Far-Off Non-Measured Performance in Vaneless Twin-Entry or Dual-Volute Radial Turbines

Serrano¹,

Arnau²,

García-Cuevas³

et al. 2020

Applied Sciences

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The current investigation describes in detail a mass flow oriented model for extrapolation of reduced mass flow and adiabatic efficiency of double entry radial inflow turbines under any unequal and partial flow admission conditions. The model is based on a novel approach, which proposes assimilating double entry turbines to two variable geometry turbines (VGTs) using the mass flow ratio ( MFR ) between the two entries as the discriminating parameter. With such an innovative approach, the model can extrapolate performance parameters to non-measured MFR s, blade-to-jet speed ratios, and reduced speeds. Therefore, the model can be used in a quasi-steady method for predicting double entry turbines performance instantaneously. The model was validated against a dataset from two different double entry turbine types: a twin-entry symmetrical turbine and a dual-volute asymmetrical turbine. Both were tested under steady flow conditions. The proposed model showed accurate results and a coherent set of fitting parameters with physical meaning, as discussed in this paper. The obtained parameters showed very similar figures for the aforementioned turbine types, which allows concluding that they are an adequate set of values for initializing the fitting procedure of any type of double entry radial turbine.

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Section: Reduced Mass Flow Fittingmentioning

confidence: 99%

Section: Dual-volute Turbinementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Robust Adiabatic Model for a Quasi-Steady Prediction of Far-Off Non-Measured Performance in Vaneless Twin-Entry or Dual-Volute Radial Turbines

Serrano¹,

Arnau²,

García-Cuevas³

et al. 2020

Applied Sciences

View full text Add to dashboard Cite

show abstract

“…To understand the flow loss in the two-stage turbine system deeply, the instant flow loss in each component was analyzed. The flow losses in five components, including volute, HPT rotor, intermediate duct, LPT stator and rotor, were calculated by Equations (10), (11), (12), (13) and (14), respectively. Suppose that the static pressure at location 6 is kept constant, the maximum expansion power produced by the fluid at location 1 (Ps,1-6) is obtained by the isentropic process from point 1 to point 6.…”

Section: Flow Loss Analysis Of Two-stage Turbine Under Pulsating Condmentioning

confidence: 99%

“…As the amplitude increases, the area enclosed by the hysteresis becomes larger, leading to larger turbine flow loss. Mingyang [13] proposed a method to comprehensively evaluate the influence of frequency and amplitude on a mixed-flow rotor. The study showed that the product of Strouhal number (St) and the pulse magnitude (M), St • M can effectively reflect turbine unsteadiness.…”

Section: Introductionmentioning

confidence: 99%

Unsteady Flow Loss Mechanism and Aerodynamic Improvement of Two-Stage Turbine under Pulsating Conditions

Zhao

Zhuge

et al. 2019

Entropy

Self Cite

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The developments of two-stage turbocharging and turbocompounding promote the application of the two-stage turbine system in internal combustion engines. Since the turbine suffers from the pulsating exhaust, the performance deteriorates significantly from steady conditions. In the paper, the pulsating flow losses in the two-stage turbine are analyzed and a control method is proposed to improve the turbine performance. ANSYS CFX, which is a commercial software for computational fluid dynamic, is applied to resolve the three-dimensional unsteady flow problem. The accuracy of the simulation method is verified by the experimental data from each turbine. Firstly, the impacts of pulse amplitudes on transient loss of each component of the two-stage turbine are studied. Then flow field analysis is carried out to understand details of the unsteady flows. It is found that the variation of incidence angle at the low-pressure turbine (LPT) rotor tip is significantly larger than that at rotor hub, which causes severe flow loss near leading edge. As a result, the LPT performance drops down significantly. To improve the LPT performance, the blade shape at tip is modified. The aerodynamic performances of turbines with three different shapes under high- and low-load pulsating flow conditions are evaluated. It is found that increased inlet blade angle and medium thickness achieves good aerodynamic performance. The rotor averaged efficiency is improved by 2.27% under high-load pulsating condition.

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The influence of a radial turbine volute on back-disk impingement cooling performance

Lü

Wenjiao³

2020

J Braz. Soc. Mech. Sci. Eng.

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Due to the restricted size of micro-gas turbines, the difficulty of cooling their radial turbines and raising their inlet temperature has been an ongoing focus in their research. In this paper, a back-disk impingement cooling technology for radial turbines is proposed. The study focuses on the influence of the non-uniform circumferential flow field generated by radial turbine volutes on the back-disk's cooling characteristics. The study was carried out by using a conjugated heat transfer numerical simulation method. The results showed that the circumferential non-uniform distribution of the flow field caused by the volute can significantly impact the relative distribution of cooling efficiency across the surface of the back-disk and can decrease the average cooling efficiency of the back-disk surface by 1.8-6.0% in comparison with when the flow field is uniform. Back-disk jet cooling reduces the efficiency of a turbine and, if the volute is generating a non-uniform flow field, this further decreases the turbine's efficiency. It was found, however, that the influence of back-disk jet cooling on the expansion ratio of the turbine can be ignored.

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An investigation on unsteadiness of a mixed-flow turbine under pulsating conditions

Cited by 27 publications

References 19 publications

A Robust Adiabatic Model for a Quasi-Steady Prediction of Far-Off Non-Measured Performance in Vaneless Twin-Entry or Dual-Volute Radial Turbines

A Robust Adiabatic Model for a Quasi-Steady Prediction of Far-Off Non-Measured Performance in Vaneless Twin-Entry or Dual-Volute Radial Turbines

Unsteady Flow Loss Mechanism and Aerodynamic Improvement of Two-Stage Turbine under Pulsating Conditions

The influence of a radial turbine volute on back-disk impingement cooling performance

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