Effects of thermal and compositional gradients and turbulence transport on detonation formation

Tianhan Zhang, Weiqi Sun, Liang Wang, Yiguang Ju

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

Abstract

The effects of thermal and fuel stratification and turbulent transport on knocking formation are numerically modeled in the negative temperature coefficient (NTC) region using dimethyl ether/air mixtures with a detailed chemistry. The critical conditions of knocking formation with thermal and fuel concentration gradients are examined. The effects of turbulence timescales on knocking development and knocking strength are explored. The results show that either a thermal gradient, concentration gradient, or combine gradients can initiate knocking. A unified criterion and diagram for knocking formation including both thermal and fuel concentration gradients as well as the normalized length scale of gradient fields is demonstrated. The results show that turbulence transport can delay knocking/detonation transition and dramatically reduce detonation strength due to turbulent mixing. It is found that when turbulence timescale is much shorter than the ignition delay time of the gradient field, the knocking formation will be suppressed. The present research provides important insights of knocking formation and control of knocking using stratifications and turbulence in the real engines.

Original languageEnglish (US)
Title of host publicationAIAA Scitech 2019 Forum
PublisherAmerican Institute of Aeronautics and Astronautics Inc, AIAA
ISBN (Print)9781624105784
DOIs
StatePublished - Jan 1 2019
EventAIAA Scitech Forum, 2019 - San Diego, United States
Duration: Jan 7 2019Jan 11 2019

Publication series

NameAIAA Scitech 2019 Forum

Conference

ConferenceAIAA Scitech Forum, 2019
CountryUnited States
CitySan Diego
Period1/7/191/11/19

All Science Journal Classification (ASJC) codes

  • Aerospace Engineering

Keywords

  • Concentration gradient
  • Knocking and detonation
  • Temperature gradient introduction
  • Turbulent transport

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