High-speed visualization of fuel spray impingement in the near-wall region using a DISI injector

N. Kawahara, K. Kintaka, Eiji Tomita

Research output: Chapter in Book/Report/Conference proceedingConference contribution


We used a multi-hole injector to spray isooctane under atmospheric conditions and observed droplet impingement behaviors. It is generally known that droplet impact regimes such as splashing, deposition, or bouncing are governed by the Weber number. However, owing to its complexity, little has been reported on microscopic visualization of poly-dispersed spray. During the spray impingement process, a large number of droplets approach, hit, then interact with the wall. It is therefore difficult to focus on a single droplet and observe the impingement process. We solved this difficulty using high-speed microscopic visualization. The spray/wall interaction processes were recorded by a high-speed camera (Shimadzu HPV-X2) with a long-distance microscope. We captured several impinging microscopic droplets. After optimizing the magnification and frame rate, the atomization behaviors, splashing and deposition, were recorded. Then, we processed the images obtained to determine droplet parameters such as the diameter, velocity, and impingement angle. Based on this information, the critical threshold between splashing and deposition was investigated in terms of the normal and parallel components of the Weber number with respect to the wall. The results suggested that, on a dry wall, we should set the normal critical Weber number to 300.

Original languageEnglish
Title of host publicationSelected Papers from the 31st International Congress on High-Speed Imaging and Photonics
EditorsTakeharu Goji Etoh, Hiroyuki Shiraga, Takeharu Goji Etoh
ISBN (Electronic)9781510611009
Publication statusPublished - 2017
Event31st International Congress on High-Speed Imaging and Photonics - Osaka, Japan
Duration: Nov 6 2016Nov 10 2016

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


Other31st International Congress on High-Speed Imaging and Photonics


  • Direct-injection spark-ignition engine
  • High-speed visualization
  • Splash
  • Spray impingement

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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