Heat transfer enhancement of round impinging jet by orifice nozzle (Effects of contraction area ratio)
✍ Scribed by Mizuki Kito; Toshihiko Shakouchi; Tatsuji Sakamoto; Koichi Tsujimoto; Toshitake Ando
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 786 KB
- Volume
- 37
- Category
- Article
- ISSN
- 1099-2871
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✦ Synopsis
The effects of the nozzle contraction ratio on the flow and heat transfer characteristics of an orifice impinging jet were investigated in this experiment. The nozzle diameter was d o = 10.0 mm = const., and the contraction area ratio CR = (d o /d i ) 2 , where d i is the inner pipe diameter was varied from CR = 1.00 to 0.11 and the nozzle-plate distance was varied from H/d o = 2.0 to 5.0. The nozzle Reynolds number was Re = 1.5 × 10 4 = const. The flow characteristics were clarified by measuring the pressure and velocity distributions on the plate and flow visualization. The Nusselt number obtained from measuring the temperature distribution on the plate of an orifice impinging jet with a CR of 0.11 and 0.69 were respectively larger by 19% and 9% than those of a pipe impinging jet (CR = 1.00), because the centerline velocity of the orifice jet was larger than that of the pipe jet. Under the same operation power, an orifice impinging jet has improved heat transfer characteristics.