Dissertation
Dissertation > Mathematical sciences and chemical > Mechanics > Fluid Mechanics > Jet

Study on Quasi-Two-Dimensional Submerged Vertical Supersonic Gas Jets

Author GuoQiang
Tutor ShiHongHui
School Zhejiang University of Technology
Course Fluid Machinery and Engineering
Keywords Quasi-two-dimensional submerged vertical gas jets Flow visualization Dynamical instability of flow Relevance analysis Dimensional analysis
CLC O358
Type Master's thesis
Year 2010
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The technology of gas jets is in extensively adopted in aerospace engineering、chemical industry、metallurgy etc. Gas jets in air has already been studied widely and deeply, and currently submerged gas jets are also attached more attention, and now gas-liquid two-phase、the violently interaction between gas and water and the dynamical instability of flow are becoming the focal points of the study of the subject ; Especially for the submerged gas jets at supersonic conditions, the problem of flow instability are caused by couple effect between complex shock-wave system and gas-liquid adulterateion will become more complicated,so the flow intability study including experimental study and numerical simulation study on it need further works.This thesis has studied the quasi-two-dimensional submerged vertical supersonic gas jets through experiment and numerical evaluation. This thesis mainly includes seven parts as following: (1)The pure gas under-expanded jets have been studied as preparatory study by commercial software Fluent and correlation theory,the results testify that there is complex shock-wave system existing in the jet potential core zone;(2)A convenient and repeatable experimental system for studying on submerged vertical supersonic gas jets has established, and we find shock-wave feedback and bulging phenomenon in jet potential core zone through visualization study of dynamical characteristic of vertical gas jets; (3) The statistics analysis of experimental result indicates that shock-wave feedback, the frequency and intensity of shock-wave feedback decrease obviously with the increasing the under-expanded level and the velocity Mach of jet, but the intensity of single shock-wave feedback event has strong randomness; (4)By comparing the characteristic of shock-wave feedback occurred in free surface condition and non-free surface condition, we discovery the effect of non-free surface operating condition to the flow instability of jet potential core zone is barely existing; (5) The study on the relationship between low-frequency and high-amplitude high-shock-wave feedback and low-frequency and high-amplitu- de bulge testifies that there is a kind of relevance surely existed between them; (6) Dimensional analysis result indicates that the dynamical characteristic of the submerged jet is associated with the value of dimensionaless parameters: modified Froude Number Fr′,Euler number Eu and modified Strouhal number (pl/pg)1/2St, and the experimental result proves the feasibility of them; (7) The full developed flow region has been studied experimental, the last part is to discuss the wobble characteristic of gas jets.The thesis has done in-depth studies of dynamical characteristic of gas-liquid and enriched the contents of gas-liquid two-phase subject, and the work will be a very solid foundation for further research study.

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