Study on mechanisms of wetting area formation and wetting front behavior during jet quenching of hot surface

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K06127
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Thermal engineering
• Research Institution: Saga University
• Principal Investigator: Mitsutake Yuichi 佐賀大学, 海洋エネルギー研究センター, 教授 (20253586)
• Research Collaborator: LIU Yang ; Monde Masanori ; Fukuda Akito ; Nakai Hiroshi ; Goto Takeshi
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 噴流冷却 / ぬれ / ウェッティングフロント / 遷移沸騰 / 衝突噴流

Outline of Final Research Achievements

An experimental study was conducted to elucidate characteristics of transient cooling heat transfer during impinging jet quenching on a hot surface being much higher than the boiling temperature. Since the quenching heat transfer is strongly governed with recovery of wetted area on the surface, measurement techniques with optical and thermal sensors were developed to characterize the wetting front (W.F.), that is specified the outer boundary of the wetted area. Characteristics of the transient behavior of the W.F. and heat transfer in the vicinity of the W.F. were clarified for different liquid temperatures, jet velocities and initial solid temperatures. A model to estimate the W.F. behavior was also proposed with coupling analysis of the transient heat conduction in the solid body with the heat transfer of the impinging jet flow on the surface. The model was verified with the experimental data.

Free Research Field

熱工学

Academic Significance and Societal Importance of the Research Achievements

工業的に幅広い応用分野を持つ高温面噴流冷却では，固液接触時の急速蒸気生成により安定なぬれ状態が生じない膜沸騰伝熱から，高温面のぬれ回復に伴って核沸騰あるいは単相熱伝達へ遷移し，ぬれ回復による沸騰遷移時に冷却速度が急増する．高温面上のぬれ面を規定するぬれ先端のウエッティングフロント（WF）の挙動は，冷却速度を予測する上で不可欠な情報となる．本研究で得られたWF位置の時間変化特性とその挙動予測モデルは，噴流による高温面冷却の応用分野，例えば鉄鋼材料の製造プロセスにおける温度制御の高精度化への寄与が期待される．