Experimental procedure for the characterization of turbocharger’s waste-gate discharge coefficient

José Ramón Serrano,Vishnu Samala,Tiseira Andrés,Francisco José Arnau

doi:10.1177/1687814017728242

José Ramón Serrano, Vishnu Samala + Show 2 more

Open Access

https://doi.org/10.1177/1687814017728242

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Abstract

Nowadays, the turbocharger has become one of the key components for automotive spark-ignition engine improvements (fed with both liquid and gaseous fuels), as a support for the boosting and downsizing concept to reduce fuel consumption and exhaust emission. In gasoline engines, the usage of the waste-gate valve typically regulates the maximum boost pressure in the turbocharger system, to protect the engine and the turbocharger at high engine speeds. To improve the transient response at low engine speeds, two-stage turbocharger is widely used. Two-stage systems are composed of several valves to regulate the flow to control the boosting of the system. Like a bypass valve between the turbines, a check valve is present between the compressor and a waste-gate valve for the low-pressure turbines. This article deals with a methodology for characterizing the discharge coefficient of an electronic waste-gate valve in the turbocharger. To estimate the gas flow over the same in one-dimensional models, an empirical model is correlated and validated. For this, a constant-stream experimental work has been carried out on a test rig at different valve position openings, with high turbine inlet temperatures. Finally, an optimal map of discharge coefficient has been drawn out through interpolation method, which can integrate into the full one-dimensional turbocharged engine model system, to calculate the actual mass flow through the waste-gate valve.

Highlights

Improving the performance of vehicle engines, like noise,[1] gaseous emissions control[2,3] as well as meeting future real driving emissions regulation[4] and reducing the fuel consumption[5] has become a key target for the automotive propulsion system
There is a continuous increment in vehicle performance and drive-ability,[6] and both needed to satisfy customer requirements
Only a small-size turbine can be driven to enough speed so that the compressor can supply the appropriate boost pressure to CMT-Motores Termicos, Universitat Politecnica de Valencia, Valencia, Spain

Summary

Introduction

Improving the performance of vehicle engines, like noise,[1] gaseous emissions control[2,3] as well as meeting future real driving emissions regulation[4] and reducing the fuel consumption[5] has become a key target for the automotive propulsion system. Turbocharger manufacturers[10] and one-dimensional (1D) engine simulation software[2,11] treat the rotor and internal waste-gate as two nozzles operating side by side and having the same temperatures and pressures in both the upstream and downstream of the turbine For both the rotor and waste-gate, the control volume has been obtained throughout the boundaries of the physical turbine, and no addition has been made for losses due to the flow dividing or combining at the inlet and outlet, respectively, within the turbine housing.[8] The mass flow rate across the turbine upon the opening of the waste-gate is taken as the sum of waste-gate mass flow rate, estimated by the discharge coefficient (obtained with no flow through rotor) and rotor mass flow rate (measured with waste-gate closed) along with expansion ratio throughout the turbine. The turbocharger is tested in a test rig in steady flow conditions at several opening and closing positions of the valve with high turbine inlet temperature

Methodology

Findings

Conclusion