Effects of Orifice Internal Flow on Transverse Injection into Subsonic Crossflows

아음속 유동장에 수직분사시 오리피스 내부유동 효과에 대한 연구

  • 김정훈 (서울대학교 기계항공공학부) ;
  • 안규복 (서울대학교 기계항공공학부) ;
  • 윤영빈 (서울대학교 기계항공공학부)
  • Published : 2003.03.01

Abstract

Effects of the orifice internal flow such as cavitation and hydraulic flip on transverse injection into subsonic crossflows have been studied. The liquid column breakup length and the liquid column trajectory were measured by changing the orifice diameter (d), the orifice length/orifice diameter (L/d), the injection pressure and the shapes (sharp and round) of orifice entrance, and were compared with previous results. It is found that cavitation bubbles, which occur inside the sharp-edged orifice, make the liquid jet very turbulent and especially in the orifices with L/d = 5 hydraulic flip appear as cavitation bubbles are emitted from the orifice. The breakup length is shorter as cavitation bubbles grows and hydraulic flip appears. However, the liquid column trajectories normalized by the effective diameter and the effective momentum ratio have a similar tendency irrespective of cavitation and hydraulic flip.

본 연구에서는 캐비테이션과 수력튀김과 같은 유동 현상이 수직 분사된 액체 제트의 분열에 미치는 영향을 살펴보았다. 오리피스 지름, 오리피스의 길이대 지름비, 오리피스 입구의 형상 그리고 배출 압력을 변화시켜가며 내부 유동 변화를 살피고 수직분사시 액주의 분열 거리와 제적을 구하여 기존의 연구 결과와 비교하고 분석하였다. 실험 결과 곡률이 없는 경우(sharp edged)의 오리피스에서는 어느 정도 이상의 압력에서 모두 캐비테이션이 발생하였고 곡률이 없는 경우 중 길이대 지름비가 작은 오리피스에선 캐비테이션 성장에 의한 수력튀김(hydraulic flip)현상도 관찰할 수 있었다 수직분사시 캐비테이션이 성장할수록 그리고 수력튀김 현상이 나타날 때 액주의 분열거리는 상당히 감소한다는 것을 알 수 있었다. 하지만 곡률이 있는 경우와 없는 경우 모두 유량 계수를 고려한 유효지름과 유효 모멘텀 플럭스 비에 대해 거의 같은 궤적 형상을 나타낸다는 것을 알 수 있었다.

Keywords

References

  1. Chen, T. H., Smith, C. R., Schommer, D. G., and Nejad, A. S., 'Multi-Zone Behavior of Transverse Liquid Jet in High-Speed Flow,' AIAA Paper 93-0453, Jan. 1993
  2. Schetz, J. A., and Padhye, A., 'Penetration and Breakup of Liquids in Subsonic Airstreams,' AIAA Journal. Vol. 15, No. 10, pp. 1385-1390, 1977 https://doi.org/10.2514/3.60805
  3. Wu, P. -K., Kirkendall, K. A., Fuller, R. P., and Nejad, A. S., 'Breakup Processes of Liquid Jets in Subsonic Crossflows,' Journal of Propulsion and Power, Vol. 13, No.1, pp. 64-73, 1997 https://doi.org/10.2514/2.5151
  4. Nguyen, T. T., and Karagozian, A. R. 'Liquid Fuel Jet in Subsonic Crossflow,' Journal of Propulsion and Power, Vol. 8, No.1, pp. 21-29, 1992 https://doi.org/10.2514/3.23437
  5. Schetz, J. A., Kush, E. A., Joshi, P. B., 'Wave Phenomena in Liquid Jet Breakup in a Supersonic Crossflow,' AIAA Journal, Vol. 18, No.7, pp. 774-778, 1980 https://doi.org/10.2514/3.7687
  6. Wotel, G. J., Gallagher, K. E., Caron, S. D., Rosfjord, T. J., Hautman, D. J., and Spadaccini, L. J., 'High Speed Turboramjet Combustor Technology Program,' Wright Lab., TR-91-2043, WrightPatterson AFB, OH, 1991
  7. Geery, E. L. and Margetts, M. J., 'Penetration of a high Velocity Gas Stream by a Water Jet,' Journal of Spacecraft, Vol. 6, No.1, pp. 79-81, 1969 https://doi.org/10.2514/3.29538
  8. Inamura, T. and Nagai, N., 'Spray Characteristics of Liquid Jet Traversing Subsonic Airstream,' Journal of Propulsion and Power, Vol. 13, No.2, pp. 250-256, 1997 https://doi.org/10.2514/2.5156
  9. Inamura, T., Trajectory of a Liquid Jet Traversing Subsonic Airstreams,' Journal of Propulsion and Power, Vol. 16, No.1, pp. 155-157, 2000 https://doi.org/10.2514/2.5547
  10. Thomas, R. H. and Schetz, J. A., 'Distribution Across the Plume of Transverse Liquid and Slurry Jets in Supersonic Airflow,' AIAA Journal, Vol. 23, No. 12, pp. 1892-1901 https://doi.org/10.2514/3.9193
  11. Ingebo, R. D., 'Aerodynamic Effects of Combustor Inlet-Air Pressure on Fuel Jet Atomization,' AIAA Paper 84-1320, June 1984
  12. Nejad, A. S. and Schetz, J. A., 'Effects of Properties and Locations in the Plume on Droplet Diameter for Injection in a Supersonic Stream,' AIAA Journal, Vol. 21, No.7, pp. 956-961, 1983 https://doi.org/10.2514/3.8183
  13. Vennard, J., Elementary Fluid Mechanics, Wiley, New York, 3rd ed., pp. 216-219
  14. Celia Soterious, Richard Andrews, and Mark Smith, 'Direct Injection Diesel Sprays and the Effect of Cavitation and Hydraulic Flip on Atomization,' SAE Paper No. 950080, 1995
  15. Nurick, W. H., 'Orifice Cavitation and Its Effects on Spray Mixing', Journal of Fluid Engineering, Vol. 98, pp. 681-687, 1976 [14]Vennard, J., Elementary Fluid Mechanics, Wiley, New York, 3rd ed., pp. 216-219 https://doi.org/10.1115/1.3448452
  16. N. Tamaki, M. Shimizu, K. Nishida and H. Hiroyasu, 'Effect of Cavitation and Internal Flow on Atomization of a Liquid Jet,' Atomization and Sprays, Vol. 8, pp. 179-197, 1998
  17. Wu, p. -K., Kirkendall, K. A., Fuller, R. P., and Nejad, A. S., 'Spray Structures of Liquid Jets Atomized in Subsonic Crossflows,' Journal of Propulsion and Power, Vol. 14, No.2, pp. 173-182, 1998 https://doi.org/10.2514/2.5283