Research Development of Variable Nozzle Turbocharger Part 1: A New Axially Movable Turbocharger

As an effective means of improving engine output, turbocharging has been widely used in engines. However, due to the inherent mismatch of a turbocharger to a reciprocating machine, a turbocharged machine does have some drawbacks,such as the reduction in transient performance, low torque backup, low torque and etc. One solution to these problems is to dynamically vary the size of the turbine stage, reducing the swallowing capacity of the turbine at lower gasflows and increasing the swallowing capacity at high gasflows. A turbocharger fitted with such a turbine is called “Variable Geometry” turbocharger.

In general, there are two types of variable nozzle turbocharger. One is the traditional gas turbine approach of using a set of individually pivotable nozzle guide vanes (1) (2), and the other is with axial movable nozzle vanes (3) (4) (5). But both types are too complicated and costly to be used in small type engine.The present paper deals with a turbocharger with simple axial movable nozzle vanes, and also controbutes the the performance data of this kind of turbocharger and the experimental engine.