Abstract
Abstract Radial flow turbines are extensively used in turbocharging technology due to their unique capability of handling a wide range of exhaust gas flow. The pulsating flow nature of the internal combustion engine exhaust gases causes unsteady operation of the turbine stage. This paper presents the impact of the pulsating flow of various characteristics on the performance of a radial flow turbine. A three-dimensional computational fluid dynamic model was coupled with a one-dimensional engine model to study the realistic pulsating flow. Applying square wave pulsating flow showed the highest degree of unsteadiness corresponding to 92.6% maximum mass flow accumulation due to the consecutive sudden changes of the mass flowrates over the entire pulse. Although sawtooth showed a maximum mass flow accumulation value of 88.9%, the mass flowrates entailed gradual change and resulted in the least overall mass flow accumulation over the entire pulse. These two extremes constrained the anticipated performance of the radial flow turbine that operates under realistic pulsating flow. Such constraints could develop an operating envelope to predict the performance and optimize radial flow turbines’ power extraction under pulsating flow conditions.
Highlights
Turbocharging technology is the most feasible to recover the waste energy in internal combustion engines (ICE)and its role in engine downsizing is indispensable [1, 2]
This work investigated the performance of radial flow turbine working under unsteady mass flow condition in the turbocharging application
A 3D computational fluid dynamic model for a radial turbine stage was developed and validated against experimental results provided by the manufacturer
Summary
Turbocharging technology is the most feasible to recover the waste energy in internal combustion engines (ICE)and its role in engine downsizing is indispensable [1, 2]. The turbocharger turbines’ primary challenge is the high level of unsteadiness of the exhaust gasses flow, which is developed by the interaction between individual pulses produced by a finite number of cylinders and their propagation through the exhaust manifold [4, 5]. Such a high level of unsteadiness lead to unpredictable off-design operation. The experimental investigation of the pulsating flow effect on the turbine stage performance is virtually challenging due to the high operating temperature of the exhaust gases [6]. Conventional approaches, such as mean-line modelling and quasi-steady flow assumptions, could not capture these changes due to the complexity of pulsating flow admission [7,8,9]
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