1999 Fiscal Year Final Research Report Summary
FLUID DYNAMIC, HEAT TRANSFER AND COMBUSTION OF LIQUID FUEL DROPLET COLLIDING WITH HEATED SUBSTRATEA
| Project/Area Number |
10650748
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
化学工学一般
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
FUKAI Jun KYUSHU UNIVERSITY, DEPARTMENT OF CHEMICAL SYSTEMS AND ENGINEERING, ASSOCIATE PROFESSOR, 大学院・工学研究科, 助教授 (20189905)
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| Co-Investigator(Kenkyū-buntansha) |
MOROZUMI Yoshio KYUSHU UNIVERSITY, DEPARTMENT OF CHEMICAL SYSTEMS AND ENGINEERING, RESEARCH ASSOCIATE, 大学院・工学研究科, 助手 (60304747)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Droplet / Impingement / Heated surface / Contact angle / Evaporating meniscus / Heat Transfer / Fluid Dynamics / Numerical Simulation |
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| Research Abstract |
The impingement of liquid droplets on hot solid surfaces is of interest in a number of industrial areas. It is of great importance to understand fluid dynamics of liquid droplets for further development of these industrial processes. The droplet impact dynamics is known to depend on the wall temperature. However, this reason has not been clarified.
This study attempts to explain the change in impact droplet dynamics with surface temperature through dynamic contact angle. Evaporating meniscus are macroscopically modeled to estimation dynamic contact angles during droplet impingement. The model was incorporated with the simulation code for the fluid dynamics and heat transfer. In the experiments, n-heptane and water droplets impacted a stainless-steel plate surface heated from room temperature to above the Leidenfrost temperature. Time variation of the spreading diameter, droplet height and apparent contact angle are measured. The numerical results are compared with the experimental resul
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ts, to discuss capability of the present mode. The efforts of this study are summarized bellow :
1. For n-heptane droplets, an increase in the wall temperature leads to decreases in the slat diameter and the time required to reach a maximum splat diameter. It also causes greater elongation of the droplet during the recoiling process. For water droplets, on the other hand, there is no effect of the wall temperature on the dimensions of the spreading droplet (though nucleate boiling depends on the wall temperature). The effect of the wall temperature is observed during the recoiling process.
2. The developed models are numerically solved using a finite element method. The model almost predicts the experimental time variation of the droplet dimensions for each wall temperature.
3. Equilibrium and nonequilibrium models for estimating the evaporation rate from meniscus are compared. As a result, the former model gives a better prediction as for the deformation process of the droplets.
4. The difference between the wall-temperature dependence of the deformation process of the two droplet is found to deduce from the difference between the temperatures at the droplet/substrate interface. Less
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