DOI QR코드

DOI QR Code

A Study on Quantification of Damping Efficiency of Acoustic Cavities by Absorption Coefficient

흡음 계수를 이용한 연소불안정 제어용 음향공의 감쇠 정량화

  • 차정필 (충남대학교 대학원 항공우주공학과) ;
  • 송재강 (충남대학교 대학원 항공우주공학과) ;
  • 김흥집 (한국항공우주연구원 연소기팀) ;
  • 고영성 (충남대학교 항공우주공학과)
  • Published : 2007.05.31

Abstract

A Helmholtz resonator as a stabilization device to control high-frequency combustion instabilities in liquid rocket engine is adopted and its damping capacity is verified by linear acoustic analysis and atmospheric acoustic tests. To compare the results of acoustic attenuation effect in accordance with uni-resonator's geometry, quantitative analyses were made in the cases of various orifice diameters and lengths. Next, in the experiments to compare the results of acoustic attenuation effect by a difference in the number of resonators, damping capacity of harmful resonant frequency was improved by the increase of the number of resonators. On the other hand, attenuation efficiency of the frequency tended rather to lower due to over damping from the point of view of absorption coefficient. As the result, tuning the suitable geometry for the resonator to the resonant frequency is required for the control using the resonator. Also, the design of resonator's geometry and the choice of its number are important to put up the optimal efficiency in consideration of restriction of its volume.

액체로켓엔진에서 발생하는 고주파 연소 불안정 제어를 위한 수동 안정화 제어 기구로 음향공을 적용하여, 선형 음향 해석 및 상온 음향 실험을 통해 감쇠 효과의 적합성을 검증하였다. 단일 음향공의 기하학적 형상에 따른 음향 감쇠 효과를 비교하기 위하여 오리피스 직경, 길이를 변화시킨 몇 가지 음향공 모델에 대해 유해 공진주파수 감쇠 효과를 정량적으로 비교, 분석하였다. 다음으로 음향공의 개수에 따른 음향 감쇠 효과를 비교하였다. 주파수 응답함수를 통한 유해주파수 감쇠 성능은 개수 증가에 따라서 우수해졌지만 흡음계수를 통한 최적의 효율 관점에서 볼 때 오히려 과도한 댐핑으로 인한 해당 주파수의 감쇠 효율이 낮아지는 경향이 발생한다. 결론적으로 음향공을 이용한 제어를 위해서는 유해주파수를 감쇠시킬 수 있는 기하학적 형상을 통한 정확한 동조가 필요하다. 또한, 부피의 제약을 고려한 최적의 효율을 발휘할 수 있는 음향공의 형상 설계와 개수의 선택이 절대적으로 필요함을 입증한다.

Keywords

References

  1. Harrje, D. J., and Reardon, F. H (eds), 'Liquid Propellant Rocket combustion instability', SP-194, NASA, 1972
  2. Natanzon, M. S., Combustion Instability, (Natanzon, M. S. and Culick, F. E. C., eds), 1996
  3. Christensen, E., and Nesman, T., 'Fastrac Rocket Engine Combustion Chamber Acoustic Cavities', The Tenth Annual Symposium of the Penn State University Propulsion Engineering Research Center, 1998, pp. 18-23
  4. McGough, C. B., McBride, J. M., and Hewitt, R. A, 'Acoustic Liner Feasibility Program', NASA CR-111405, 1970
  5. Cha, J. P., and Ko, Y. S., 'Geometric Effects on Damping Characteristics of Acoustic Cavity for the Control of Combustion Instabilities' Journal of the Korean Society for Aeronautical and Space Sciences, Vol. 34, No.6, 2006, pp. 59-66
  6. Kim, H. S., and Sohn, C. H., 'Experimental Study of Acoustic Damping Induced by Gas-Liquid Scheme Injectors in a Combustion Chamber' Journal of Mechanical Science and Technology, Vol. 20 No.6, 2006, pp. 896-904 https://doi.org/10.1007/BF02915952
  7. Laudien, E., Pongratz, R., and Preclik, D., 'Experimental Procedures Aiding the Design of Acoustic Cavities', in Liquid Rocket Engine Combustion Instability, Progress in Astronautics and Aeronautics, Vol. 169, AIAA, 1995, pp. 377-399
  8. Tsuji, T., Tsuchiya, T. and Kagawa, Y., 2002, 'Finite Element and Boundary Element Modelling for the Acoustic Wave Transmission in Mean Flow Medium', Journal of Sound and Vibration, Vol. 255, pp. 849-866 https://doi.org/10.1006/jsvi.2001.4189
  9. Kim, S.-K., Kim, H. J., and Sohn, C. H, 'Development of Analysis Code for Evaluation of Acoustic Stability of Rocket Engine Combustor with Various Designs', Journal of the Korean Society for Aeronautical and Space Sciences, Vol. 32, No. 6, 2004, pp. 110-116
  10. Saad, Y. and Schultz, M., 1986, 'GMRES: A Generalized Minimal Residual Algorithm for solving Nonsymmetric Linear Systems', SIAM Journal on Scientific and Statistical Computing, Vol. 7, pp. 856-869 https://doi.org/10.1137/0907058
  11. 손채훈, '배플이 장착된 로켓엔진 연소기의 음향장 해석', 대한기계학회논문집(B), 제 26 권, 제 1호, 2002, pp. 966-975
  12. 고영성, 이광진, 김홍집, '액체로켓엔진 연소실에서의 상온 음향 시험', 대한기계학회논문집 (B), 제 28권, 제 1호, 2003, pp. 16-23
  13. Kim, H. J., Kim, S.-K., and Seol, W. S., 'Acoustic Analysis for Design Optimization of Hub-Blade Baffle in Liquid Rocket Engine', Transactions of the KSME(B), Vol. 28, No. 8, 2004, pp. 945-952 https://doi.org/10.3795/KSME-B.2004.28.8.945
  14. ISO 10534-1, 'Acoustics - Determination of Sound Absorption Coefficient and Impedance in Impedance Tubes - Part 1: Method using standing wave ratio', 1996
  15. ISO 10534-2, 'Acoustics - Determination of Sound Absorption Coefficient and Impedance in Impedance Tubes - Part 2: Transfer function method', 1998

Cited by

  1. Aerodynamic Characteristics and Wing Tip Vortex Behavior of Three-Dimensional Symmetric Wing According to Heights vol.36, pp.12, 2012, https://doi.org/10.3795/KSME-B.2012.36.12.1161
  2. Damping Characteristic of Helmholtz Resonator according to Its Geometry and Sound Pressure Level vol.38, pp.10, 2010, https://doi.org/10.5139/JKSAS.2010.38.10.966