Transactions of the Korean Society of Mechanical Engineers B (대한기계학회논문집B)

The Korean Society of Mechanical Engineers (대한기계학회)
권호 표지
DOI QR코드

DOI QR Code

Numerical Study of Flow Characteristics in Elementary Paths of Velocity-Control Trim

속도 제어형 트림의 단위 요소 유로의 유동특성에 관한 수치적 연구

  • Received : 2010.06.01
  • Accepted : 2010.12.14
  • Published : 2011.03.01
Download PDF
⟨ Previous Next ⟩

Abstract

We investigate the flow characteristics of elementary-flow paths with $90^{\circ}$ bends; a velocity-control trim consists of such paths. For geometric similarity, the width and length of each path are selected, and the number of bends is 0, 4, or 8. The flow tests are conducted with the same flow-path elements. The numerical results are in good agreement with the experimental data. In elements without bends, the volume flow rate decreases with the length of the flow path, with a constant pressure drop between the inlet and the outlet. However, in flow paths with $90^{\circ}$ bends, it increases and then decreases with the length of the flow path. For a fixed number of $90^{\circ}$ bends, better pressure-drop characteristics are observed as the length of the flow path increases. For a fixed flow-path length, a flow-path element with more bends has a smoother pressure drop along the path.

속도 제어형 트림을 구성하는 기본 유로 요소로서 $90^{\circ}$의. 굴곡을 갖는 유로를 선택하여 폭과 길이가 상사성을 가지도록 설정하고 0, 4, 8 회의 굴곡을 갖는 총 48개의 단위 유로 요소에 대해 유동 해석을 수행하였다. 먼저, 동일 요소에 대한 실험과 수치해석 결과를 비교하여 수치해석 접근방법의 타당성을 검증하였다. 일정한 차압에 대해 굴곡횟수에 따른 유량을 계산한 결과, 굴곡이 없으면 유로의 길이가 증가함에 따라 유량이 감소하였다. 굴곡이 있는 경우, 유로가 길어지면 유량이 증가하다가 감소하였다. 케비테이션의 억제의 관점에서 압력장을 분석하였고, 이로부터 동일한 굴곡횟수를 가질 경우 유로가 길수록 유로를 따라 발생하는 압력 강하 특성이 우수함을 알았다. 또한, 유로의 길이가 같은 경우에는 굴곡횟수가 많을수록 압력이 완만히 감소하는 특성을 가짐을 알 수 있었다.

Keywords

References

  1. Jang, H., Yoon, I. S. and Kim, Y. B., 2008, "The Intact Evaluation of High Pressure Control Valve Trim Parts," Proceedings of KSME Fall Conference, pp. 581-584.
  2. ANSI/ISA, 2002, "ANSI/ISA-S75: Flow Equations for Sizing Control Valves."
  3. Rahmeyer, W. J., Miller, H. L. and Sherikar, S. V., 1995, “Cavitation Testing Result for a Tortuous Path Control Valve," in Cavitation and Multiphase Flow (Edited by J. Katz and Y. Matsumoto), American Society of Mechanical Engineers, FED-Vol. 210, pp. 62-66.
  4. Cavallo, P. A., 2005, "Transient Simulations of Valve Motion in Cryogenic System," 35th AIAA Fluid Dynamics Conference and Exhibit, AIAA-2005-5152.
  5. Davis, J. A. and Stewart, M., 2002, "Predicting Globe Control Valve Performance Part Ⅰ:CFD Modeling," Journal of Fluid Engineering, Vol. 124, pp. 772-777. https://doi.org/10.1115/1.1490108
  6. Jang, H., Kim, Y. B., Kwon, K. J., I. S. Yoon, J. W. Yoon, 2009, "Development of the Control Valve Helical Trim Under High Pressure Drop for Nuclear Power Plant," Proceedings of KSME fall Conference, pp. 2309-2314.
  7. Yoon, I. S., Kim, Y. B., Jang, H., Hwang, J. H. and Kang, Y. M., 2008, "The Performance Comparison Evaluation of Control Valve Shape," Proceedings of KSME fall Conference, pp. 2771-2776.
  8. Yoon, J. Y., Byun, S. J., Yang, J. M. and Lee, D. H., 2001, "Numerical Analysis of the 3-D Flow Field in a Glove Valve Trim under High Pressure Drop," Transactions of Korean Fluid Machinery Association, Vol. 4, No. 3, pp. 14-20.
  9. Ahn, Y. J., Kim, B. J. and Shin, B. R., 2007, "Numerical Analysis on Flow Characteristics of High Pressure Drop Control Valve with Anti- Cavitation Trim," Journal of Korean Fluid Machinery Association, Vol. 10, No. 4, pp. 61-70. https://doi.org/10.5293/KFMA.2007.10.4.061
  10. Alexandrou, A., 2002, Principles of Fluid Mechanics, Prentice-Hall, New Jersey.
  11. Menter, F. R., Kuntz, M. and Langtry, R., 2003, "Ten years of Industrial Experience With the SST turbulence Model," in Turbulence Heat and Mass Transfer 4 (Edited by K. Hangalic, Y. Nagano, and M. Tummers), Begell House Inc., New York, pp. 625-632.
  12. Kim, T. Y., Lee, B. S. and Lee, D. H., 2005, "Study on the Unsteady Wakes Past a Square Cylinder near a Wall," Journal of Mechanical Science and Technology, Vol. 19, No. 5, pp. 1169-1181. https://doi.org/10.1007/BF02984039
  13. ANSYS Inc, 2009, CFX User Manual, Ver. 12, Southpointe.
  14. ANSYS Inc, 2009, CFX Advanced Turbulance Models, Southpointe.
  15. Mentor, F., Ferreira, J. C., Esch, T. and Konno, B., 2003, "The SST Turbulence Model with Improved Wall Treatment for Heat Tranfer Predictions in Gas Turbines," Proceedings of the International Gas Turbine Congress, IGTC-2003-TS-059.
  16. KS, 1999, "KS B 2101: Test Procedures for Flow Coefficient Valves."
  17. Skousen, P. L., 2005, Valve Handbook, Mc-Graw Hill, New York.
  18. Brennen, E. C., 1995, Cavitation and Bubble Dynamics, Oxford Univ. Press, Oxford.
  19. Franc, J. P.. Michel, J. P.. 2004, Fundamentals of Cavitation, Springer, New York.

Cited by

  1. Numerical Study on Cavitation Reduction in Velocity-Control Trim of Valve with High Pressure Drop vol.37, pp.9, 2013, https://doi.org/10.3795/KSME-B.2013.37.9.863