Computational Study of a Radial Flow Turbine Operates Under Various Pulsating Flow Shapes and Amplitudes

Rezk, Ahmed; Sharma, Sidharth; Barrans, Simon; Hossain, Abul Kalam; Lee, Samuel P.; Imran, Muhammad

doi:10.1115/1.4050968

Cited by 7 publications

(3 citation statements)

References 35 publications

(45 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Despite that, internal combustion engine exhaust gases have a pulsating flow nature which causes unsteady behavior of the turbine stage. Rezk et al (2021) presented the realistic effects of the pulsating flow of different characteristics on the performance of a radial turbine by coupling a 3-D CFD model with a 1-D engine model. Also, Mosca et al (2021) used unsteady CFD to study the effects of the parameterized characteristics of the mass flow pulse.…”

Section: Introductionmentioning

confidence: 99%

CFD Study of the Impacts of a Turbocharger’s Various Wastegate and Bypass Configurations on the Efficiency and the Flow Field of its Radial Turbine

2023

JAFM

View full text Add to dashboard Cite

Turbocharger systems enhance the engine power and efficiency, reduce its pollution, and downsize the engine volume. As the significance of exploiting turbochargers in gasoline engines is surging among automobile manufacturers, the necessity of improvement in the system components becomes more critical. This paper investigates the impacts of a turbocharger turbine bypass and wastegate geometry alterations on the performance and the flow field characteristics via numerical simulations. The numerical method verification and mesh independence study are performed for the original geometry. The simulation results of the altered geometries indicate that better alignment between the bypassed and the bulk flows leads to higher efficiency of the turbocharging system. In addition, the bent or elbow-shaped and protruded turbine walls immediately downstream of the wheel are found to be unfavorable. It is also uncovered that if the wastegate shape and the housing walls are designed in such a way that the effects of ensuing vortices are minimized, it improves the stage efficiency, which is desirable for two-stage turbochargers. Furthermore, a novel manufacturable design is proposed in this study, which increases the efficiency and useful power by 19.9% and 6.7%, respectively.

show abstract

Section: Introductionmentioning

confidence: 99%

CFD Study of the Impacts of a Turbocharger’s Various Wastegate and Bypass Configurations on the Efficiency and the Flow Field of its Radial Turbine

2023

JAFM

View full text Add to dashboard Cite

show abstract

“…This is motivated by the fact that the higher is the amplitude, the larger is the amount of mass flow which is found at a condition far from the cycle-averaged steady condition. Recently, Lee et al [21] and Rezk et al [22] investigated the effects of different pulse shapes on the turbine performance. In these numerical studies, the square profile was shown to have the largest detrimental effect on the turbine efficiency compared to realistic, sinusoidal, and triangular profiles.…”

Section: Introductionmentioning

confidence: 99%

Turbocharger Radial Turbine Response to Pulse Amplitude

Mosca

Lim

Mihăescu

2022

Journal of Energy Resources Technology

View full text Add to dashboard Cite

Under on-engine operating conditions, a turbocharger turbine is subject to a pulsating flow and, consequently, experiences deviations from the performance measured in gas-stand flow conditions. Furthermore, due to the high exhaust gases temperatures, heat transfer further deteriorates the turbine performance. The complex interaction of the aerothermodynamic mechanisms occurring inside the hot-side, and consequently the turbine behavior, is largely affected by the shape of the pulse, which can be parameterized through three parameters: pulse amplitude, frequency, and temporal gradient. This paper investigates the hot-side system response to the pulse amplitude via Detached Eddy Simulations (DES) of a turbocharger radial turbine system including exhaust manifold. Firstly, the computational model is validated against experimental data obtained in gas-stand flow conditions. Then, two different mass flow pulses, characterized by a pulse amplitude difference of 5%, are compared. An exergy-based post-processing approach shows the beneficial effects of increasing the pulse amplitude. An improvement of the turbine power by 1.3%, despite the increment of the heat transfer and total internal irreversibilities by 5.8% and 3.4\%, respectively, is reported. As a result of the higher maximum speeds, internal losses by viscous friction are responsible for the growth of the total internal irreversibilities as pulse amplitude increases.

show abstract

“…This is motivated by the fact that the higher is the amplitude, the larger is the amount of mass flow which is found at a condition far from the cycle-averaged steady one. Recently, Lee et al [20] and Rezk et al [21] investigated the effects of different pulse shapes on turbine performance. The square profile was found to have the largest detrimental effect on the turbine efficiency compared to realistic, sinusoidal, and triangular profiles.…”

Section: Introductionmentioning

confidence: 99%

Influence of Pulse Characteristics on Turbocharger Radial Turbine

Mosca

Lim

Mihăescu

2021

Journal of Engineering for Gas Turbines and Power

View full text Add to dashboard Cite

Due to the reciprocating engine, a pulsating flow occurs in the turbine turbocharger, which experiences conditions far from the continuous flow scenario. In this work, the effects of the characteristics of the mass flow pulse, parameterized through amplitude, frequency and temporal gradient, are decoupled and studied via unsteady Computational Fluid Dynamics calculations under on-engine operating conditions. Firstly, the model is validated based on comparisons with experimental data in steady flow conditions. Then, the effect of each parameter on exergy budget is assessed by considering a +/-10% variation with respect to a baseline pulse. The other factors defining the operating conditions (e.g. mass flow, shaft speed and inflow exergy) are kept the same as the baseline. The adopted approach enables to completely isolate the effects of each parameter in contrast with previous literature studies. Based on the results observed, pulse amplitude is identified as the primary parameter affecting the hot-side system response in terms of turbine performance, heat transfer and entropy generation, while frequency and temporal gradient show a smaller influence compared to it. As the pulse amplitude increases, the turbine work is reported to improve up to 9.4%. Smaller variations are observed for the frequency and temporal gradient analysis. With a 10% increase of the pulse frequency the turbine work is registered to improve by 5.0%, while the same percentage reduction of the temporal gradient leads to an increase of turbine work equal to 3.6%.

show abstract

Computational Study of a Radial Flow Turbine Operates Under Various Pulsating Flow Shapes and Amplitudes

Cited by 7 publications

References 35 publications

CFD Study of the Impacts of a Turbocharger’s Various Wastegate and Bypass Configurations on the Efficiency and the Flow Field of its Radial Turbine

CFD Study of the Impacts of a Turbocharger’s Various Wastegate and Bypass Configurations on the Efficiency and the Flow Field of its Radial Turbine

Turbocharger Radial Turbine Response to Pulse Amplitude

Influence of Pulse Characteristics on Turbocharger Radial Turbine

Contact Info

Product

Resources

About