Effect of jet inclination angle on the flow field within a hybrid solar receiver combustor

This paper reports on a systematic numerical study that investigates the interaction of four isothermal jets within an annular chamber under conditions relevant to a Hybrid Solar Receiver Combustor (HSRC). The HSRC features a cavity that is operable as a combustion chamber, an aperture to admit concentrated solar radiation into the chamber, multiple burners to direct a flame into the chamber, and a heat exchanger within it to absorb the heat from both energy sources (depending on the mode of operation). The HSRC geometry is simplified in this study to include a cylindrical cavity with four jets, representing the burners, which are configured in an annular arrangement and aligned at an angle to the axis. The aperture to the cavity is closed while the four jets interact with each other and with the cavity wall. The jet inclination angle (αjet) was varied from 0° to 90°, while the jet Reynolds number and the number of jets were fixed at Rej = 15,000 and 4, respectively. The numerical study utilised the commercial Computational Fluid Dynamics (CFD) code ANSYS CFX. The results show that the αjet significantly influences the flow field with smaller αjet (0° ≤ αjet < 10°) leading to a strong inward annular recirculation while larger αjet (10° ≤ αjet < 90°) generates an outward annular recirculation with a strong back-flow through the aperture plane. Four flow regimes were identified, namely: inward recirculation dominant flow (0° ≤ αjet < 10°); outward recirculation dominant flow(10° ≤ αjet < 40°); outward recirculation with back-flow(40° ≤ αjet < 60°); and jet impinging flow (60° ≤ αjet < 90°). The findings are presented and discussed with relevance to heat transfer within the HSRC.