Reactive Experimental PIV Analysis of Pulsating Flow Exiting from Cyclic Deflagrative Pressure Gain Combustion

In spite of the intense research interest in the integration of Pressure Gain Combustion (PGC) systems with a turbomachinery module, limited studies have been conducted regarding the experimental investigation of the strong spatio temporal perturbations of these unconventional machines outflow. This paper focuses on experimentally characterizing the perturbing exhaust flow of a Constant Volume Combustor (CVC). Preceding numerical analysis offers a transition duct able to attenuate the CVC produced unsteadiness and connect this PGC with a turbomachinery module. In fact, the transition duct is manufactured, while a pair of windows are introduced allowing for high frequency Particle Image Velocimetry (PIV) analysis. In addition, fast response pressure sensors in the combustion chamber, upstream and downstream of the transition duct, are implemented. A parametric analysis of the rotational frequency of the inlet outlet rotary valve pair is conducted. The perturbing outflow of this PGC is characterized and experimentally visualized for the first time. Moreover, the attenuation performance of the transition duct on the CVC produced unsteadiness is evaluated for different cycle frequencies. The transition duct is proved to be able to alleviate the spatial and time dependent unsteadiness by CVC, offering crucial evidence and conclusions for the future industrial integration of the CVC with a High Pressure Turbine stage.