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가상경계 격자볼쯔만법을 이용한 프로펠러의 유동특성해석 방법에 관한 연구

Numerical Technique to Analyze the Flow Characteristics of a Propeller Using Immersed Boundary Lattice Boltzmann Method

  • 김형민 (경기대학교 기계시스템공학과)
  • Kim, Hyung Min (Dept. of Mechanical System Engineering, Kyonggi Univ.)
  • 투고 : 2016.02.05
  • 심사 : 2016.04.07
  • 발행 : 2016.07.01

초록

프로펠러에 의한 추력은 유체의 유입 속도와 익의 회전속도에 의해 생성되며 그 성능을 전진비, 추력계수, 동력계수와 같은 무차원수로 나타내고 있다. 이 연구에서 회전체의 성능을 분석하기 위한 수치적 방법으로 STL형식의 회전체 형상을 인식할 수 있는 가상경계법을 적용한 격자볼쯔만법을 제안한다. 이 가상경계법으로 프로펠러의 회전에 의한 유동을 구현하기 위해서 프로펠러의 표면 격자점에서 속도와 유동장의 격자점에서 유속의 차를 이용하여 계산한 체적력을 볼쯔만방정식의 외력항으로 적용하게 된다. 제안한 방법을 검증하기 위하여 4개의 익을 가지고 있는 프로펠러를 이용해 레이놀즈수가 100, 500, 1000이고 전진비가 0.2~1.4일 때 유동해석을 수행하였으며 그 결과로 부터 전형적인 프로펠러의 성능특성을 얻을 수 있었다. 높은 레이놀즈수와 전진비를 갖는 유동에서 해석 안정성을 확보하기 위해서는 익의 표면에 구성한 최대 격자의 크기와 유동장에 구성한 격자 크기의 비가 3 이하로 유지해야 하며 충분히 긴 후류영역을 확보할 필요가 있다.

The thrust force created by a propeller depends on the incoming flow velocity and the rotational velocity of the propeller. The performance of the propeller can be described by dimensionless variables, advanced ratio, thrust coefficient, and power coefficient. This study included the application of the immersed boundary lattice Boltzmann method (IBLBM) with the stereo lithography (STL) file of the rotating object for performance analysis. The immersed boundary method included the addition of the external force term to the LB equation defined by the velocity difference between the lattice points of the propeller and the grid points in the domain. The flow by rotating a 4-blade propeller was simulated with various Reynolds numbers (Re) (including 100, 500 and 1000), with advanced ratios in the range of 0.2~1.4 to verify the suggested method. The typical tendency of the thrust efficiency of the propeller was obtained from the simulation results of different advanced ratios. It was also necessary to keep the maximum mesh size ratio of the propeller surface to a grid size below 3. Additionally, a sufficient length of the downstream region in the domain was maintained to ensure the numerical stability of the higher Re and advanced ratio flow.

키워드

참고문헌

  1. "Ansys Fluent Theory Guide," Ansys, Inc, USA
  2. Wang, Y., Brasseur, J. G. and Banco, G. G., 2010, "Computational Modeling in Biomechanics," Springer Science Business, U.S.A.
  3. Kim, H. M., Myung S Jhon, 2007, "Numerical Study on Flow Over Oscillating Circular Cylinder Using Curved Moving Boundary Treatment," Trans. Korean Soc. Mech. Eng. B, Vol. 31, No. 11, pp. 895-903. https://doi.org/10.3795/KSME-B.2007.31.11.895
  4. Kim, H. M., 2008, "Numerical Study on Flow Moving Circular Cylinder Near the Wall Using Immersed Boundary Lattice Boltzmann Method," Trans. Korean Soc. Mech. Eng. B, Vol. 32, No. 12, pp. 924-930. https://doi.org/10.3795/KSME-B.2008.32.12.924
  5. Kim, H. M., 2009, "Numerical Study on Aerodynamci Characteristics of the Moving Circular Cylinder Near the Wavy Wall," Trans. Korean Soc. Mech. Eng. B, Vol. 33, No. 2, pp. 107-115. https://doi.org/10.3795/KSME-B.2009.33.2.107
  6. Kim, H. M., 2010, "Numerical Study on Turbulent Flow over Cylinder Using Immersed Boundary Lattice Boltzmann Method with Multi Relaxation Time," Korean Society of Computational Fluid Engineering, Vol. 15, No. 2, pp. 21-27.
  7. Kim, H. M., 2011, "Numerical Analysis of the Airfoil in Self-propelled Fish Motion Using Immersed Boundary Lattice Boltzmann Method," Korean society of computational fluid engineering, Vol. 16, No. 2, pp. 24-29. https://doi.org/10.6112/kscfe.2011.16.2.024
  8. Bhatnagar P. L., Gross, E. P. and Krook, M., 1954, "A Model for Collision Processes in Gases. I: Small Amplitude Processes in Charged and Neutral Onecomponent System," Phys. Rev. Vol. 94, pp. 511-525. https://doi.org/10.1103/PhysRev.94.511
  9. Chen, H., 1993, "Discrete Boltzmann Systems and Fluid Flow," Comp. Phys., Vol. 7, pp. 632-637. https://doi.org/10.1063/1.4823237
  10. He X., Zou Q., Luo L.-S. and Dembo, M., 1997, "Analytic Solutions of Simple Flow and Analysis of Non-slip Boundary Conditions for the Lattice Boltzmann BGK Model," J. Stat. Phys., Vol. 87, pp. 115-136. https://doi.org/10.1007/BF02181482
  11. Succi, S., 2001, "Lattice Boltzmann Equation for Fluid Dynamics and Beyond," Oxford University Press, USA.
  12. Buick, J. M. and Grated, C. A., 2000, "Gravity in a Lattice Boltzmann Model," Physical Review E, Vol. 61, No. 5, pp. 5307-5320. https://doi.org/10.1103/PhysRevE.61.5307