Influence of speed and frequency towards the automotive turbocharger turbine performance under pulsating flow conditions

Padzillah, Muhamad Hasbullah; Rajoo, Srithar; Martinez-Botas, Ricardo

doi:10.1016/j.enconman.2014.01.047

Cited by 40 publications

(12 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In fact, the hysteresis loop at pulsating condition is caused by both the filling-empty effect and wave dynamics in the compressor. This phenomenon has been previously observed and comprehensively studied in the turbine exposed to pulsating incoming flow in literatures [20,21]. In the studies, it has been confirmed that the mass imbalance in the turbine is a reasonable criteria to evaluate the unsteadiness of the turbine performance under pulsating incoming flow [13].…”

Section: Instantaneous Flow and Performance At Pulsating Backpressuresupporting

confidence: 53%

Experimental study on performance of centrifugal compressor exposed to pulsating backpressure

Shu

Yang

Zhang

et al. 2019

Aerospace Science and Technology

View full text Add to dashboard Cite

Pressure fluctuations in intake manifold of Internal Combustion Engine introduce a pulsating boundary condition to the centrifugal compressor. In this study, the performance of centrifugal compressor exposed to pulsating backpressure is experimentally investigated. Unsteady performance and surge characteristic of the compressor at different pulsating conditions are analyzed. Results show that instantaneous performance of the compressor forms a hysteresis loop encapsulating steady performance. A correlation of compressor unsteadiness with pulse frequency, magnitude, and local slope of the characteristic curve is obtained based on measurements. Cycle-average performance of the compressor is notably lower than that at constant conditions. Specifically, the averaged peak efficiency at pulsating condition drops 3%~7%. Fast Fourier Transformation method is applied to study surge characteristics at pulsating conditions. Results manifest that compressor surge is postponed remarkably by pulsating backpressure at all conditions. As the compressor approaches to small mass flow rate, flow fluctuations decay quickly and then increase dramatically when the surge happens, forming the variation with 'V-shape' for frequency domains. This phenomenon is resulted from the influence of the slope of characteristic curve on the filling-empty and compressor stability. Smaller slope produces less filling-empty and hence smaller size of the loop, but reduces the stability of compressing system and initiates surge.

show abstract

Section: Instantaneous Flow and Performance At Pulsating Backpressuresupporting

confidence: 53%

Experimental study on performance of centrifugal compressor exposed to pulsating backpressure

Shu

Yang

Zhang

et al. 2019

Aerospace Science and Technology

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%

“…Unsteady turbine performance is significantly influenced by the pulse amplitude and frequency. Average turbine efficiency improves with higher pulse frequency [11,12]. However, the pulse amplitude shows a disadvantageous impact on turbine performance.…”

Section: Introductionmentioning

confidence: 99%

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

Zhao

Zhuge

et al. 2019

Entropy

View full text Add to dashboard Cite

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.

show abstract

“…An oversimplified model may not represent the real engine any more. The inflow conditions into the turbocharger turbine can crucially effect its performance [9]. Usually, the valve timing and the valve opening-speed is studied and optimized by one-dimensional simulations, where the quality of the flow field and therefore the inflow conditions into the turbocharger turbine are not accounted for.…”

Section: Introductionmentioning

confidence: 99%

Flow effects due to pulsation in an internal combustion engine exhaust port

Semlitsch¹,

Wang²,

Mihăescu³

2014

Energy Conversion and Management

View full text Add to dashboard Cite

In an internal combustion engine, the residual energy remaining after combustion in the exhaust gasses can be partially recovered by a downstream arranged device. The exhaust port represents the passage guiding the exhaust gasses from the combustion chamber to the energy recovering device, e.g. a turbocharger. Thus, energy losses in the course of transmission shall be reduced as much as possible. However, in one-dimensional engine models used for engine design, the exhaust port is reduced to its discharge coefficient, which is commonly measured under constant inflow conditions neglecting engine-like flow pulsation. In this present study, the influence of different boundary conditions on the energy losses and flow development during the exhaust stroke are analyzed numerically regarding two cases, i.e. using simple constant and pulsating boundary conditions. The compressible flow in an exhaust port geometry of a truck engine is investigated using three-dimensional Large Eddy Simulations (LES). The results contrast the importance of applying engine-like boundary conditions in order to estimate accurately the flow induced losses and the discharge coefficient of the exhaust port. The instantaneous flow field alters significantly when pulsating boundary conditions are applied. Thus, the induced losses by the unsteady flow motion and the secondary flow motion are increased with inflow pulsations. The discharge coefficient decreased about 2% with flow pulsation. A modal flow decomposition method, i.e. Proper Orthogonal Decomposition (POD), is used to analyze the coherent structures induced with the particular inflow and outflow conditions. The differences in the flow field for different boundary conditions suggest to incorporate a modeling parameter accounting for the quality of the flow at the turbocharger turbine inlet in one-dimensional simulations.

show abstract

Influence of speed and frequency towards the automotive turbocharger turbine performance under pulsating flow conditions

Cited by 40 publications

References 11 publications

Experimental study on performance of centrifugal compressor exposed to pulsating backpressure

Experimental study on performance of centrifugal compressor exposed to pulsating backpressure

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

Flow effects due to pulsation in an internal combustion engine exhaust port

Contact Info

Product

Resources

About