|Budget Amount *help
¥3,400,000 (Direct Cost : ¥3,400,000)
Fiscal Year 1998 : ¥700,000 (Direct Cost : ¥700,000)
Fiscal Year 1997 : ¥2,700,000 (Direct Cost : ¥2,700,000)
Enhancement of the mixing and diffusion of jet flow itself or between jet flow and the ambient is very important because of the improvement of heat transfer characteristics of impinging jet, combustion efficiency of burner and chemical reaction, efficient diffusion of warmed waste water, and so on. The entertainment of air bubble into water by plunging jet is also influenced by the fluctuation of water jet surface. In this study, in order to enhance the fluctuation of jet flow, about resonance jet, control of annular jet by coaxial round jet their flow caracteristics was made clear by the measurement of mean and fluctuating velocity components, and about plunging jet the relation between fluctuation of water jet surface and amount of entraind air was also examined. Major results are as follows.
1. Resonance jet : (1) The turbulence intensity, spread of jet and decrease of jet center line velocity are larger than those of jet from orifice. (2) The dominant resonance frequency increases w
ith increasing volume of resonance room and velocity. (3) The flow characteristics, dominant frequency, mean and fluctuating velocity profiles and spread of jet, can be controlled by changing the volume of resonance room.
2. Plunging jet : (1) The flow pattern of impinging jet can be classified into three groupes. (2) In the case of pipe nozzle with highly fluctuated water jet surface the amount of entrained air is larger than that of orifice and aeration can be done efficiently. (3) Using a fluctuation enhancement element the amount of entrained air is larger than that of the pipe nozzle and aeration can be done more efficiently.
3. Control of annular jet by coaxial round jet : (1) The turbulence intencity near nozzle exit of double coaxial jet is relatively enhanced comparing with the jet from round nozzle. (2) The flow characteristics, mean and fluctuating velocity components, of annualr jet can be controlled by coaxial round jet.
The flow characteristics of jet flow is influenced by the fluctuation, turbulence, and it was shown that the fluctuation can be enhanced and controlled by a few simple methods. Less