Unified length scale of spray structure by unlike impinging jets

Chihiro Inoue, Yuta Takeuchi, Koji Nozaki, Takehiro Himeno, Toshinori Watanabe, Go Fujii, Yu Daimon

Research output: Contribution to journalArticlepeer-review

6 Citations (Scopus)


In bi-propellant thrusters, impinging type injectors are widely used to deliver propellants to a combustion chamber. By impinging the jet streams of fuel and oxidizer, the spray spreads while the two liquids mix. To design the injectors, several correlations related to injection conditions have been proposed (e.g., Rupe factor), and practically utilized over the last half-century. However, the physical meanings of the past correlations are not well understood, because the essential scale of the spray structure is elusive. In this paper, we derive the global length scale of the spray produced by impinging injectors of unlike doublet, fuel-oxidizer-fuel triplet, and oxidizer-fuel-oxidizer triplet in a consistent manner. The unified length scale is found representing the spray width ratio of oxidizer to fuel evidenced by comprehensive cold-flow tests including several past studies, covering various parameters such as injector types, nozzle diameters, physical properties of working liquids, and injection velocities. Finally, we clearly provide the physical meaning based on practical correlations in a phenomenological sense.

Original languageEnglish
Pages (from-to)213-218
Number of pages6
JournalTransactions of the Japan Society for Aeronautical and Space Sciences
Issue number4
Publication statusPublished - 2019

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering
  • Space and Planetary Science


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