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Internal Flow and Spray Characterization of Multi-Hole Injectors: Comparison with Single-Hole Injectors

2020; American Chemical Society; Volume: 34; Issue: 6 Linguagem: Inglês

10.1021/acs.energyfuels.0c00473

1520-5029

Yu Jin, Pengbo Dong, Chang Zhai, Keiya Nishida, Yoichi Ogata, Xianyin Leng,

Rocket and propulsion systems research

Single-hole (SH) injectors were compared with multi-hole (MH) injectors to reveal the differences in nozzle internal flow and spray propagation. The multi-phase flow inside the nozzles was numerically investigated. The nonevaporating near-field spray images were captured to observe the spray dispersion profile near the nozzles using a microscopic imaging technique. Moreover, the laser diagnostics technique of laser absorption scattering (LAS) was implemented to measure the mixture concentration distribution under evaporating condition. The result indicates that a sharp change in the flow direction of MH injector can lead to the cavitation region downstream to the hole axis. However, the cavitation inside the SH injector only occurs on the wall of the hole. The unstable cavitation flow inside the MH nozzle hole is an important cause for spray perturbations in nozzle near-field. Furthermore, at the beginning of the needle raising process, the injection rate curve of SH injector with smaller discharge area rises faster than that of MH injector, caused by the higher sac pressure. The lower sac pressure, worse second breakup, and spray plumes interference result in the sprays of MH injector entraining less ambient gas per unit mass of fuel, compared with that of SH injectors. Moreover, the larger the hole diameter is, the larger the gap of evaporation ratio between the SH and MH injectors would be.