Abstract

On vehicles equipped with a turbocharged engine, there is a risk of compressor surge. This surge generates instabilities that lead to driving inconvenience, or even mechanical failure of the supercharging system. In general, the surge appears rather in transient operation: sudden closing of the throttle valve on gasoline engine, regulation of the EGR on diesel engine linked also to turbine regulation (VNT device or Waste Gate). On a turbocharger test stand, we set up the surge line in a “conventional way”: stationary experiments. Then we set up this line in transient conditions for different positions of an electric throttle placed upstream the compressor. It appears that: the surge limit is pushing back to lower flow rates when it is determined in transient; the surge limit is pushing back to lower flow rates when closing the throttle valve. The tests were carried on by the transient analysis of the surge during a quick closing-opening of the electric throttle valve.

Highlights

  • Most automotive engines are turbocharged to reduce CO2 emission and fuel consumption

  • The manufacturer ensures that the engine operates out of the surge phenomenon zone of the compressor in stationary regime

  • The surge limit appears for lower flow rates when it is determined in transient;

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Summary

Introduction

Most automotive engines are turbocharged to reduce CO2 emission and fuel consumption. The manufacturer ensures that the engine operates out of the surge phenomenon zone of the compressor in stationary regime To achieve this condition, the manufacturer keeps a margin from surge limit defined by the turbocharger supplier. The surge limit has been researched in numerous studies seeking to determine a criterion to detect the occurrence of surge [1, 2] and on the validity of this limit on engine operation. These studies were mainly carried out for stationary operating regimes. Appearance of surge is studied for a quick closing of the throttle valve

Test bench description
Definition of the surge limit in stationary test
Definition of the surge limit in transient test
Surge limits comparison
Surge limit evolution closing-opening
Findings
Conclusion
Full Text
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