شبیه سازی گردابه های بزرگ جریان خنک کاری لایه ای تک مجرا و مجموعه سوراخ خنک کاری

نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانشکده مهندسی مکانیک، دانشگاه سمنان.

2 دانشگاه صنعتی مالک اشتر

چکیده

در این مطالعه جریان خنک­کاری لایه­ای بر روی یک صفحه تخت به منظور بررسی اثرات به‌کارگیری مجموعه سوراخ بر اثربخشی خنک­کاری لایه­ای با استفاده از رهیافت RANS و LES شبیه­سازی شده است. هندسه­های مورد مطالعه شامل تک سوراخ استوانه­ای با قطر mm 1/11 و یک مجموعه سوراخ با 14 سوراخ استوانه­ای 97/2 میلی‌متری می­باشند، به طوری که سطح مقطع خروجی لوله خنک­کاری در هر دو حالت یکسان است. این مجموعه سوراخ به شکل ذوزنقه­ای چیدمان شده است. شبیه­سازی عددی در نسبت چگالی 6/1، نسبت طول به قطر 4، زاویه 35 درجه و نسبت دمش 25/1 صورت گرفته است. نتایج به دست آمده نشان می­دهند که جایگزینی یک تک سوراخ با مجموعه سوراخ شکل داده شده، منجر به افزایش قابل توجهی در اثربخشی خنک­کاری لایه­ای در هر دو جهت طولی و عرضی می­گردد، به طوری که افزایش در حدود 94 درصدی در میانگین سطحی اثربخشی خنک­کاری لایه­ای را در پی دارد. این افزایش در پی تغییر در ساختار گردابه­ها حاصل می­گردد. در مجموعه سوراخ خنک­کاری، مقیاس گردابه­های سنجاقی شکل کوچکتر از گردابه­های تک سوراخ است و شکل­گیری آنها در مکانی دورتر از سوراخ خنک­کاری صورت می­گیرد. در ساختار مجموعه سوراخ جفت گردابه­های anti-jet تشکیل می­شوند که جهت چرخش این گردابه­ها بر خلاف جهت CRVP است.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Large eddy simulation of single and multi-holes of film cooling

نویسندگان [English]

  • Yaser Taheri 1
  • Mehran Rajabi Zargarabadi 1
  • Mehdi Jahromi 2
1 Faculty of Mechanical Engineering, Semnan University, Semnan, Iran
2 Malek Ashtar University of Technology, Tehran, Iran
چکیده [English]

  In this research, numerical studies have been performed by Reynolds averaged Navier Stokes (RANS) and large eddy simulations (LES) to investigate the effect of a novel film cooling design multi-holes on the film cooling effectiveness over a flat surface. A single cylindrical hole with 11.1 mm diameter and multi-holes (14 holes with a diameter of 2.97 mm) with fan configuration are considered for simulations. Numerical simulations are performed at a fixed density ratio of 1.6, length-to-diameter of 4, an inclined angle of 35o and blowing ratio 1.25. The results of the present study show that replacing a single hole with multi-holes results in a considerable increase in film cooling effectiveness in both axial and lateral directions, so that leads to an increase of about 94 percent in the area-averaged film cooling effectiveness. In the fan-shaped configuration, the scale of hairpin vortices is smaller than the single cylindrical hole, and forming of the vortices occurs in farther regions downstream of the hole. A pair of anti-jet vortices is formed in the structure of the multi-holes and the rotation direction of these vortices is opposite to the CRVP direction.
 

کلیدواژه‌ها [English]

  • film cooling
  • multi-holes
  • large eddy simulation
  • coherent structures

مراجع

  1. C. Han, S. Dutta, and S. V. Ekkad, "Gas turbine heat transfer and cooling technology", Taylor and Francis Publications, New York, USA, 2000.
  2. L. Johnson, and V. Shyam, "Large Eddy Simulation of a Film Cooling Flow Injected from an Inclined Discrete Cylindrical Hole into a Crossflow with Zero-Pressure Gradient Turbulent Boundary Layer", NASA/TM, No. E-18382, 2012
  3. Zolfagharian, M. Rajabi-Zargarabadi, A. S. Mujumdar, M. S. Valipour and M. Asadollahi, "Optimization of turbine blade cooling using combined cooling techniques" Engineering Applications of Computational Fluid Mechanics, vol. 3, Pp. 462-475, 2014.
  4. Rajabi‐Zargarabadi, and F. Bazdidi‐Tehrani, "Implicit algebraic model for predicting turbulent heat flux in film cooling flow" International Journal for Numerical Methods in Fluids, vol. 64, Pp. 517-531, 2010.
  1. [5]    S. R. Shine, S. Sunil Kumar, and B. N. Suresh, "Internal wall-jet film cooling with compound angle cylindrical holes", Energy Conversion and Management, vol. 68, Pp. 54-62, 2013.
  1. Moeini, and M. Rajabi Zargarabadi, "Genetic algorithm optimization of film cooling effectiveness over a rotating blade" International Journal of Thermal Sciences, vol. 125, Pp. 248-255, 2018.
  2. Azzi, and B. A. Jubran, "Numerical modeling of film cooling from converging slot-hole", Heat and Mass Transfer, vol. 43, Pp. 381–388, 2007.
  3. Nasir, S. V. Ekkad, and S. Acharya, "Effect of compound angle injection on flat plate surface film cooling with large stream wise injection angle", Experimental Thermal and Fluid Science, vol. 25, Pp. 23-29, 2001.
  4. W. Lee, J.J. Park, and J. S. Lee, "Slow visualization and film cooling effectiveness measurements around shaped holes with compound angle orientations", International Journal of Heat and Mass Transfer, vol. 45, Pp. 145-156, 2002.
  5. H. Kim, and K. Y. Kim, "Film-cooling performance of converged-inlet hole shapes", International Journal of Thermal Sciences, vol. 124, Pp. 196–211, 2018.
  6. J. Ely, and B. A. Jubran, "A numerical study on increasing film cooling effectiveness through the use of sister holes", ASME Paper, GT-50366, 2008.
  7. Saumweber, and A. Schulz, "Effect of geometry variations on the cooling performance of fan-shaped cooling holes", Proceedings of ASME Turbo Expo 2008, GT2008–51038, )2008(.
  8. S. Fua, W. S. Chaoa, M. Tsubokura, C. G. Lic, and W. H. Wangd, "Investigation of boundary layer thickness and turbulence intensity on film cooling with a fan-shaped hole by direct numerical simulation", International Communications in Heat and Mass Transfer, vol. 96, Pp. 12–19, 2018.
  9. Lee, K. D., and Kim, K. Y., "Shape optimization of a fan-shaped hole to enhance film cooling effectiveness", International Journal of Heat and Mass Transfer, vol. 53, Pp. 2996–3005, (2010).
  10. Fraas, T. Glasenapp, A. Schulz, and H. Bauer, "Optimized inlet geometry of a laidback fan-shaped film cooling hole – Experimental study of film cooling performance", International Journal of Heat and Mass Transfer, vol. 128, Pp. 980–990, 2019.
  11. M. M. Abdala, and F. N. M., Elwekeel "An influence of novel upstream steps on film cooling performance", International Journal of Heat and Mass Transfer, vol. 93, Pp. 86–96, 2016.
  12. Zhang, X. Wang, and J. Li, "The effects of upstream steps with unevenly spanwise distributed height on rectangular hole film cooling performance", International Journal of Heat and Mass Transfer, vol. 102, Pp. 1209–1221, 2016.
  13. Ye, C. Liu, H. Liu, H. Zhu, and J. Luo, "Experimental and numerical study on the effects of rib orientation angle on film cooling performance of compound angle holes", International Journal of Heat and Mass Transfer, vol. 126, Pp. 1099–1112, 2018.
  14. Leblanc, D. Narzary, and S. V. Ekkad, "Film cooling performance of an anti-vortex hole on a flat plate", AJTEC2011-44161, AJTEC, Hawaii, )2011(.
  15. Singh, B., Premachandran, and M. R. Ravi, "Experimental and numerical studies on film cooling with reverse/backward coolant injection", International Journal of Thermal Sciences, vol. 111, Pp. 390-408, 2017.
  16. Chi, J. Ren, H. Jiang, and S. Zang, "Geometrical optimization and experimental validation of a tripod film cooling hole with asymmetric side holes", Journal of Heat Transfer, vol. 138, 061701, 2016.
  17. Acharya, M. Tyagi, and A. Hoda, "Flow and Heat Transfer Predictions for Film Cooling", Heat Transfer in gas turbine systems, Annals of the New York Academy of Sciences, vol. 934, Pp. 100-125, 2001.
  18. Guo, W. Schroder, and M. Meinke, "Large-eddy simulations of film cooling flows", Computers & Fluids, vol. 35, Pp. 587-606, 2006.
  19. Zhong, C. Zhou, Z. Sun, and S. Chen, "Heat transfer mechanisms of inclined jets in cross flow with different holes", International Journal of Heat and Mass Transfer, vol. 131, Pp. 664-674, 2019.
  20. Hou, F. Wen, S. Wang, Y. Luo, and X. Tang, "Large eddy simulation of the trenched film cooling hole with different compound angles and coolant inflow orientation effects", Applied Thermal Engineering, vol. 163, 114397, 2019.
  21. Tyagi, and S. Acharya, "Large eddy simulation of film cooling flow from an inclined cylindrical jet", ASME Journal of Turbomachinery, vol. 125, Pp. 734-742, 2003.
  22. Sakai, T. Takahashi, and H. Watanabe, "Large-eddy simulation of an inclined round jet issuing into a crossflow", International Journal of Heat and Mass Transfer, vol. 29, Pp. 300-310, 2014.
  23. Zamiri, S. J. You, and J. T. Chung, "Large Eddy Simulation of Unsteady Turbulent Flow Structures and Film-Cooling Effectiveness in a Laidback Fan-Shaped Hole", Aerospace Science and Technology, 105793, 2020.
  24. Wang, F. Fan, J. Zhang, Y. Huang, and H. Feng, "Large eddy simulation of film cooling flow from converging slot-holes", International Journal of Thermal Sciences, vol. 126, Pp. 238–251, 2018.
  25. H. Leedom, and S. Acharya, "Large Eddy Simulation of Film Cooling Flow Field from Cylindrical and Shaped Holes", ASME Turbo Expo 2008, Paper No. GT2008-51009, June 9–13, Berlin, Germany, )2008(.
  26. Wang, J. Zhang, H. Feng, and Y. Huang, "Large Eddy Simulation of Film Cooling Flow from A Fanshaped Hole", Applied Thermal Engineering, vol. 129, Pp. 855-870, 2018.
  27. ANSYS Inc. ANSYS FLUENT theory guide, ANSYS FLUENT 16.0.0, Cononsburg, PA, USA, 2014.
  28. H. Shih, W. W. Liou, A. Shabbir, Z. Yang, and J. Zhu, "A New k-ε Eddy-Viscosity Model for High Reynolds Number Turbulent Flows - Model Development and Validation", Computers Fluids, vol. 24, Pp. 227–238, 1995.
  29. Smagorinsky, "General circulation experiments with the primitive equations: I. The basic experiment", Mon Weather Rev, vol. 91, Pp. 99-164, 1963.
  30. L. Schmidt, B. Sen, and D. G. Bogard, "Film cooling with compound angle holes: adiabatic effectiveness", Journal of Turbomachinery, vol. 118, Pp. 807-813, 1996.
  31. A. Haven, and M. Kurosaka, "Kidney and anti-kidney vortices in crossflow jets", Journal of Fluid Mechanic, vol. 352, Pp. 27-64, 1997.
  32. K. Walters, and J. H. Leylek, "A detailed analysis of film-cooling physics: Part I –streamwise injection with cylindrical holes", ASME Journal of Turbomachinery, vol. 122, Pp. 102-112, 2000.
  33. Kohli, and D. G. Bogard, "Turbulent transport in film cooling flows", Journal of Heat Transfer, vol. 127, Pp. 513-520, 2005.
  34. F. Fric, A. Roshko, "Vortical structure in the wake of a transverse jet", Journal of Fluid Mechanics, vol. 279, Pp. 1-47, 1994.
  35. Muldoon, and S. Acharya, "Numerical investigation of the dynamical behavior of a row of square jets in cross flow over a surface", ASME paper no. 99-GT-127, )1999(.
ارسال نظر در مورد این مقاله
CAPTCHA Image

فایل ها

هم رسانی

ارجاع به این مقاله

آمار