Turbocharger Matching

Abstract

Naturally aspirated diesel engines are capable of operating over wide speed ranges. The maximum useful speed will usually be limited by poor volumetric efficiency, the inertia of the reciprocating parts or, in the case of some small high-speed engines, high frictional losses and poor combustion. An engine that is designed for variable speed operation will usually exhibit some deterioration in performance both at extreme low and high speeds. This is due to high gas frictional losses in the inlet valves and the use of valve timing optimised in the mid-speed range and a gradual mismatch between fuel injector characteristics and swirl. However, the useful speed range can be wide, since reciprocating machinery is well suited to cater for a wide range of mass flow rate.