Integration of meanline and one-dimensional methods for prediction of pulsating performance of a turbocharger turbine

Abstract Stringent emission regulations are driving engine manufacturers to increase investment into enabling technologies to achieve better specific fuel consumption, thermal efficiency and most importantly carbon reduction. Engine downsizing is seen as a key enabler to successfully achieve all of these requirements. Boosting through turbocharging is widely regarded as one of the most promising technologies for engine downsizing. However, the wide range of engine speeds and loads requires enhanced quality of engine-turbocharger matching, compared to the conventional approach which considers only the full load condition. Thus, development of computational models capable of predicting the unsteady behaviour of a turbocharger turbine is crucial to the overall matching process. A purely one-dimensional (1D) turbine model is capable of good unsteady swallowing capacity predictions, however it has not been fully exploited to predict instantaneous turbine power. On the contrary, meanline models (zero-dimensional) are regarded as a good tool to determine turbine efficiency in steady state but they do not include any information about the pressure wave action occurring within the turbine. This paper explores an alternative methodology to predict instantaneous turbine power and swallowing capacity by integrating one-dimensional and meanline models. A single entry mixed-flow turbine is modelled using a 1D gas dynamic code to solve the unsteady flow state in the volute, consequently used as the input for a meanline model to evaluate the instantaneous turbine power. The key in the effectiveness of this methodology relies on the synchronisation of the flow information of different time scales. The model is validated against experimental data generated at Imperial College London under steady and pulsating flow conditions. Three rotational speeds (27.0, 43.0, and 53.7  rps / K ) and four pulse flow frequencies (20 to 80 Hz) are considered for performance validation. In addition to the turbine performance, the common level of unsteadiness is also compared based on Strouhal number evaluations. Furthermore, comparisons are made with the quasi-steady assumption in order to understand the strengths and weaknesses of the current method for effective unsteady turbine performance prediction.

[1]  Zhengping Zou,et al.  Leading-edge redesign of a turbomachinery blade and its effect on aerodynamic performance , 2012 .

[2]  Ricardo Martinez-Botas,et al.  The development of a dynamometer for torque measurement of automotive turbocharger turbines , 2007 .

[3]  N Karamanis,et al.  Mixed-flow turbines for automotive turbochargers: Steady and unsteady performance , 2002 .

[4]  Haruo Yoshiki,et al.  A Study on Performance of Radial Turbine under Unsteady Flow Conditions , 1979 .

[5]  Ugur Kesgin,et al.  Effect of turbocharging system on the performance of a natural gas engine , 2005 .

[6]  Srithar Rajoo,et al.  Numerical Assessment of Unsteady Flow Effects on a Nozzled Turbocharger Turbine , 2012 .

[7]  Aaron Costall,et al.  A one-dimensional study of unsteady wave propagation in turbocharger turbines , 2007 .

[8]  Ricardo Chacartegui,et al.  Real time simulation of medium size gas turbines , 2011 .

[9]  Laszlo Fuchs,et al.  Numerical Computation of the Pulsatile Flow in a Turbocharger With Realistic Inflow Conditions From an Exhaust Manifold , 2009 .

[10]  Ricardo Martinez-Botas,et al.  The Pulsating Flow Field in a Mixed Flow Turbocharger Turbine: An Experimental and Computational Study , 2005 .

[11]  Ricardo Martinez-Botas,et al.  Performance prediction of a nozzled and nozzleless mixed-flow turbine in steady conditions , 2011 .

[12]  Andrew P. S. Wheeler,et al.  Design of high-efficiency turbomachinery blades for energy conversion devices with the three-dimensional prescribed surface curvature distribution blade design (CIRCLE) method , 2012 .

[13]  Joon Hock Yeo,et al.  Pulsating flow behaviour in a twin-entry vaneless radial inflow turbine , 1990 .

[14]  Shinri Szymko,et al.  The development of an eddy current dynamometer for evaluation of steady and pulsating turbocharger turbine performance , 2006 .

[15]  N. D. Whitehouse,et al.  Estimating the Effects of Altitude, Ambient Temperature and Turbocharger Match on Engine Performance , 1963 .

[16]  Ugur Kesgin,et al.  Study on the design of inlet and exhaust system of a stationary internal combustion engine , 2005 .

[17]  José Ramón Serrano,et al.  Impact of two-stage turbocharging architectures on pumping losses of automotive engines based on an analytical model , 2010 .

[18]  Ricardo Martinez-Botas,et al.  Unsteady Performance of a Double Entry Turbocharger Turbine With a Comparison to Steady Flow Conditions , 2012 .

[19]  Dimitrios C. Rakopoulos,et al.  Evaluation of the effect of engine, load and turbocharger parameters on transient emissions of diesel engine , 2009 .

[20]  Federico Millo,et al.  Analysis of different exhaust gas recirculation architectures for passenger car Diesel engines , 2012 .

[21]  Ricardo Martinez-Botas,et al.  Detailed Study of Pulsating Flow Performance in a Mixed Flow Turbocharger Turbine , 2005 .

[22]  De Winterbone,et al.  Theory of Engine Manifold Design: Wave Action Methods for IC Engineers , 2001 .

[23]  Ricardo Martinez-Botas,et al.  Mixed Flow Turbines: Inlet and Exit Flow Under Steady and Pulsating Conditions , 2001 .

[24]  Srithar Rajoo,et al.  Unsteady Performance Prediction of a Single Entry Mixed Flow Turbine Using 1-D Gas Dynamic Code Extended With Meanline Model , 2012 .

[25]  Rafea Mohamed Abd El-Maksoud,et al.  Two operating modes for turbocharger system , 2012 .

[26]  Ricardo Martinez-Botas,et al.  Assessment of Unsteady Behavior in Turbocharger Turbines , 2006 .

[27]  Ricardo Martinez-Botas,et al.  Fundamental Characterization of Turbocharger Turbine Unsteady Flow Behavior , 2007 .

[28]  Srithar Rajoo,et al.  Unsteady Effect in a Nozzled Turbocharger Turbine , 2010 .

[29]  Srithar Rajoo,et al.  Engine turbocharger performance prediction: One-dimensional modeling of a twin entry turbine , 2012 .

[30]  Luis Miguel García-Cuevas,et al.  Characterization of a radial turbocharger turbine in pulsating flow by means of CFD and its application to engine modeling , 2013 .

[31]  Srithar Rajoo,et al.  Single entry mixed flow turbine performance prediction with 1-d gas dynamic code coupled with mean line model , 2012 .

[32]  A. J. Glassman,et al.  FORTRAN program for predicting off-design performance of radial-inflow turbines , 1975 .

[33]  Peter L Meitner,et al.  Computer code for off-design performance analysis of radial-inflow turbines with rotor blade sweep , 1983 .

[34]  Ricardo Martinez-Botas,et al.  Experimental Evaluation of Turbocharger Turbine Performance Under Pulsating Flow Conditions , 2005 .