A detailed one-dimensional model to predict the unsteady behavior of turbocharger turbines for internal combustion engine applications

Abstract

This article describes an investigation of the unsteady behavior of turbocharger turbines by one-dimensional modeling and experimental analysis. A one-dimensional model has been developed to predict the performance of a vaneless radial-inflow turbine submitted to unsteady flow conditions. Different from other approaches proposed in the literature, the turbine has been simulated by separating the effects of casing and rotor on the unsteady flow and by modeling the multiple rotor entries from the volute. This is a simple and effective way to represent the turbine volute by a network of one-dimensional pipes, in order to capture the mass storage effect due to the system volume, as well as the circumferential variation of fluid dynamic conditions along the volute, responsible for variable admittance of mass into the rotor through blade passages. The method developed is described, and the accuracy of the one-dimensional model is shown by comparing predicted results with measured data, achieved on a test rig dedicated to the investigation of automotive turbochargers. The validation of the code is presented and an analysis of the flow unsteadiness, based on a variety of parameters, is proposed.

A novel pulse-adaption flow control method for a turbocharger turbine: Elastically restrained guide vane

“…19 and Piscaglia et al. 20,21 also show that the CFD is a useful tool in investigating how the turbocharger turbine performs under pulsating flow conditions.…”

Dimensionless quantification of small radial turbine transient performance

“…In reality, however, flow conditions are highly transient on-engine, with the turbine typically operating under unsteady conditions rather than the design states, making the turbocharger performance prediction challenging. 1 The pulsating character of the system due to the reciprocating movement of the piston and opening and closure of the valves is a major underlying cause of the unsteady behaviour of the flow. 2,3 Both 1D and 3D methodologies have been used to analyse turbocharger transient performance, complemented by specialist experimental techniques to capture and measure performance characteristics under these conditions.…”

“…For fluid mechanics, the degree of influence of unsteady flow is reflected by the Strouhal number. 1,22 Research by Costall et al 9,10 has highlighted that an increase in pulse frequency and, hence, the Strouhal number will result in a large difference between the steady and unsteady performances of the turbine. These findings show a strong connection between the Strouhal number and unsteady effects.…”

Experimental validation of a one-dimensional twin-entry radial turbine model under non-linear pulse conditions

“…With this purpose, Winterbone et al 5 and Winterbone and Pearson 6 performed a rigorous review on the topic. Investigators have also performed different experiments for pulsating flow in single-entry turbines, such as Torregrosa et al 7 or Serrano et al 8 for unsteady and off-design performance, Torregrosa et al 9 for diesel engines or Hohenberg et al 10 Piscaglia et al 11 show an interesting approach measuring the instantaneous pressure, temperature and mass flow in different points in the turbine inlet duct and the turbine outlet duct. Galindo et al 12 present a similar experimental methodology as the one presented in this article, being applied for a variable geometry turbine (VGT).…”