Journal of the Korean Society of Propulsion Engineers (한국추진공학회지)

The Korean Society of Propulsion Engineers (한국추진공학회)
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Effect of Orifice Geometry on Flow Characteristics of Liquid Jet from Single Hole Nozzle

오리피스 형상에 따른 단공노즐 액체제트의 유동특성

  • Song, Yoonho (School of Mechanical Engineering, Chungbuk National University) ;
  • Hwang, Donghyun (School of Mechanical Engineering, Chungbuk National University) ;
  • Ahn, Kyubok (School of Mechanical Engineering, Chungbuk National University)
  • Received : 2016.10.31
  • Accepted : 2017.01.25
  • Published : 2017.10.01
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Abstract

Effects of cavitation and hydraulic flip in circular and elliptical nozzles on the flow characteristics have been studied. Spray tests were conducted using injectors with different ratios of an orifice length(L) to a diameter(d) and of a major axis diameter(a) to a minor axis diameter(b). With the increment of an injection pressure drop, discharge coefficients slightly decreased in cavitation flows, and those suddenly dropped and were almost constant in hydraulic flip flows. For elliptical nozzles with L/b > 8 and L/a < 8, discharge coefficients and flow patterns showed different results from those in previous circular nozzles. When a flow in the elliptical nozzle was under steady condition, as the liquid column went downstream from the nozzle, its spray angle a little decreased in the plane of a major axis and increased in the plane of a minor axis.

본 연구에서는 원형 노즐과 타원형 노즐을 이용하여 공동현상과 수력튀김 현상이 유동특성에 어떠한 영향을 미치는지 파악하고자 하였다. 이를 위해 오리피스 길이 대 직경비(L/d)와 타원형 노즐의 종횡비(a/b)가 서로 다른 분사기들을 제작하여 분무실험을 수행하였다. 분사압력 증가에 따라 공동현상이 발생할 경우 유량계수가 서서히 감소하였으나 수력튀김 영역에서는 유량계수가 급격히 떨어진 후 일정한 값을 유지함을 확인하였다. 하지만 타원형 노즐에서 장축지름(a)과 단축지름(b) 대비 오리피스 길이의 비인 L/b가 8 이상, L/a가 8 이하인 경우, 유량계수 및 액체제트 형상은 기존의 원형 노즐과는 상당히 다른 결과를 나타내었다. 정상유동 상태인 경우 타원형 노즐에서 분사된 액주는 원형 노즐과는 달리 하류로 가면서 장축에서는 분무각이 감소하였으며 단축에서는 분무각이 커지는 모습을 보였다.

Keywords

References

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  1. Spray Characteristics of Liquid Jets in Acoustically-Forced Crossflows vol.22, pp.2, 2018, https://doi.org/10.6108/KSPE.2018.22.2.001
  2. Effect of Orifice Geometry on Column Trajectories of Liquid Jets in Crossflows pp.2093-2480, 2019, https://doi.org/10.1007/s42405-018-0130-3