Analysis on thermal efficiency of non-compressor type pulse detonation turbine engines

Abstract

Endo et al. (2004) applied thermodynamic analysis to a simplified Pulse Detonation Turbine Engine (PDTE) system to estimate ideal performance; the theoretical thermal efficiency of a non-compressor type PDTE system is assumed to be 20% to 30% with an ethylene-oxygen mixture. Several experimental studies were conducted using a test apparatus composed of an automobile turbocharger connected to a single-tube pulse detonation engine (PDE). The results demonstrated that the measured thermal efficiency was 1% to 5%, far lower than the theoretical thermal efficiency. These studies covered the simplest PDTE system, in which the detonation wave from a PDE tube is directly incident to a turbine and can be considered as the lowest PDTE system performance. This study clarifies the reduced thermal efficiency by building a model simulating the inside of a turbine. The relationship between the turbine peripheral velocity and thermal efficiency of a non-compressor type PDTE with an ethylene-oxygen mixture was determined based on the premise of being constant turbine peripheral velocity during one PDE cycle. The PDTE test apparatus with a single-tube PDE connected automobile turbocharger was used to verify this model experimentally. The turbine peripheral velocity was changed by changing the PDTE operating frequency and was applied to the model to obtain the relationship with thermal efficiency. As PDTE operating frequency increased, the thermal efficiency of the model gradually approached the maximum value at a constant peripheral velocity during one PDE cycle as described above. Similar trends were observed in both tests and model predictions of thermal efficiency as a function of PDTE operating frequency i.e. turbine peripheral velocity. © 2011 The Japan Society for Aeronautical and Space Sciences.