Experimental Investigation of Design Parameters in an Impingement Starting System for Turboshaft Engines

This paper investigates the influence of different design parameters of a pneumatic system used to spin-up the gas generator of a helicopter turboshaft gas turbine. The system uses supersonic nozzles to impinge air on the outer section of the compressor' s radial end-stage. After identifying the relevant variables, Design of Experiments is used to vary and investigate their effects on the performance systematically and to discover possible interactions. The results of static experiments show good accordance with analytical calculations, however, acceleration experiments revealed interesting non-linear effects.The nozzle exit Mach number was identified as the most critical parameter. The Mach number is linked with the supply pressure and is, therefore, the reason for a design conflict. Prediction models are derived to get a database for the redesign of the impingement system.     «

This paper investigates the influence of different design parameters of a pneumatic system used to spin-up the gas generator of a helicopter turboshaft gas turbine. The system uses supersonic nozzles to impinge air on the outer section of the compressor' s radial end-stage. After identifying the relevant variables, Design of Experiments is used to vary and investigate their effects on the performance systematically and to discover possible interactions. The results of static experiments show go...     »