افزایش اثربخشی خنک کاری لایه ای پره توربین در حال چرخش با استفاده از سوراخ تزریق شکل داده شده

نوع مقاله: پژوهشی

نویسندگان

دانشگاه سمنان

چکیده

در تحقیق حاضر افزایش اثربخشی خنک کاری لایه ای پره توربین با استفاده از مجرای گسترش یافته طولی انجام شده است. در این راستا خنک کاری لایه ای پره توربین در سه سرعت چرخش صفر، 300 و 500 دور بر دقیقه با استفاده از دو نوع سوراخ استوانه ای و سوراخ گسترش یافته طولی مورد بررسی قرار گرفته است. تحلیل عددی سه بعدی میدان جریان و انتقال حرارت آشفته خنک کاری لایه ای در پره توربین با استفاده از مدل های اصلاح شده رینولدز پایین k-ε انجام شده است. برای خنک کاری با سوراخ استوانه ای، نتایج شبیه سازی عددی تحقیق حاضر در سرعت های دورانی مختلف با مقادیر تجربی موجود مقایسه شده است. نتایج عددی بدست آمده نشان می دهد که مدل های رینولدز پایین توانایی قابل قبولی در پیش بینی اثربخشی خنک کاری لایه ای در پره توربین دارد. نتایج به دست آمده نشان می دهد که افزایش سرعت دورانی پره به واسطه ایجاد شتاب کریولیس، منجر به انحراف جریان هوای خنک کننده از روی خط مرکزی می شود. انحراف جریان هوای خنک کننده باعث کاهش میزان اثربخشی در خط مرکزی پره به ویژه در پایین دست سوراخ تزریق می شود. همچنین تزریق هوای خنک از طریق سوراخ گسترش یافته طولی منجر به کاهش اختلاط هوای خنک و جریان هوای گرم می شود. مقایسه نتایج نشان می دهد که اثربخشی خنک کاری سوراخ گسترش یافته طولی به طور محسوسی بیشتر از اثربخشی سوراخ استوانه ای است.

کلیدواژه‌ها


عنوان مقاله [English]

Film cooling effectiveness enhancement of rotating turbine blade using Shaped holes

نویسنده [English]

  • Mehran Rajabi Zargarabadi
چکیده [English]

This study is aimed to increase the effectiveness of film cooling in rotating blades by performing forward diffused shaped hole. For both cylindrical and forward diffused holes three different rotational speed of zero, 300 and 500 rpm have been investigated. Three-dimensional numerical simulation of turbulent flow and heat transfer in rotating reference frame are performed using modified low Reynolds k-ε model. Comparison show that low Reynolds models have acceptable ability to predict the effectiveness of film cooling of the rotating blade. The results show that by increasing the rotational speed the Coriolis acceleration consequences the deviation of the cooling air from the central line. In rotating blade, the effectiveness of the central line, especially downstream of the injection holes is reduced. Also injection of cooling air through the forward diffused hole lead to reduce the mixing of cooling air with main stream flow. Comparison of the results shows that the effectiveness of the forward diffused hole is considerably higher than the cylindrical hole.

کلیدواژه‌ها [English]

  • turbine blade
  • Film cooling
  • Turbulent heat transfer
  • Rotation speed
  • Shaped hole
 
[1] Bogard. D. G., Thole, K. A. (2006).  “Gas Turbine Film Cooling”. Journal of Propulsion and Power, Vol. 22, pp. 249–270.
[2] Bazdidi-Tehrani, F., Andrews, G.E. (1994). “Full Coverage Discrete Hole Film Cooling: Investigation of the Effect of Variable Density Ratio,” ASME Journal of Engineering for Gas Turbines and Power, Vol. 116, pp. 587-596.
[3] Amer, A.A., Jubran, B.A., Hamdan, M.A. (1992). “Comparison of Different Two Equation Turbulence Models for Prediction of Film Cooling From Two Rows of Holes”. Numerical Heat Transfer, Part A, Vol. 21, pp.143-162.
[4] Rajabi-Zargarabadi M., Bazdidi-Tehrani, F. (2010). “Implicit Algebraic Model for Predicting Turbulent Heat Flux in Film Cooling Flow”, International Journal. Numer. Meth. Fluids, Vol. 64, pp. 517–531.
[5] M. Taeibi-Rahni, M., Ramezanizadeh, D.D., Ganji, A., Darvan, E., Ghasemi, Soheil Soleimani, H., Bararnia. (2011). “Comparative Study of Large Eddy Simulation of Film Cooling Using a Dynamic Global-Coefficient Subgrid Scale Eddy-viscosity Model With RANS and Smagorinsky Modeling”. International Communications in Heat and Mass Transfer, Vol. 38, May, pp.  659-667.
[6] Lakehal, D., Theodoridis, G., Rodi, W. (1998). “Computation of Film Cooling of a Flat Plate by Lateral Injection from a Row of Holes”. Int. J. Heat & Fluid Flow, Vol. 19, pp. 418-430.
[7] Nemdili, W., Azzi, A., Theodoridis, G., Jurban, B.A. (2008). “Reynolds Stress Transport Modeling of Film Cooling at the Leading Edge of a Symmetrical Turbine Blade”. Heat Transfer Engineering, Vol. 29, pp. 950–960.
[8] Guoqiang Xu, Jianqin Zhu , Zhi Tao. (2010). “Application of the TLVA Model for Predicting Film Cooling Under Rotating Frames”. International Journal of Heat and Mass Transfer, Vol. 53, pp. 3013–3022.
[9] Ki-Don Lee, Kwang-Yong Kim. (2011). “Surrogate Based Optimization of a Laidback Fan-shaped Hole for Film-cooling”. International Journal of Heat and Fluid Flow, Vol. 32, pp. 226-238.
[10] Yao Yu, Zhang Jing-zhou, Tan Xiao-ming. (2014). “Numerical Study of Film Cooling from Converging Slot-hole on a Gas Turbine Blade Suction Side”. International Communications in Heat and Mass Transfer, Vol. 52, pp. 61–72.
[11] Zhi Tao, Zhenming Zhao, Shuiting Ding, Guoqiang Xu, Hongwei Wu. (2009). “Suitability of Three different two-equation turbulence models in predicting effusion cooling performance over a rotating blade”. International Journal of Heat and Mass Transfer, Vol 52, pp. 1268-1275.
[12] Walters, D.K., Laylek, J.H. (1996). “A Detailed Analysis of Film Cooling Physics: Part III- Streamwise Injection with Cylindrical Holes”. ASME Journal of Turbomachinary, Vol.122, pp. 122-132.
[13] Boussinesq, J. (1877). “Essay on the theory of water flow”. Memories of Science Academy (Paris), Vol. 23, pp. 601-680.
[14] Wang, S.J., Mujumdar, A.S. (2005). “A Comparative Study of Five Low Reynolds Number k-ε Model for Impingement Heat Transfer”. Applied Thermal Engineering, Vol. 25, pp. 31-44.
[15] Chang, K.C., Hsieh, W.D., Chen, C.S. (1995). “A Modified Low-Reynolds Number Turbulence Model Applicable to Recirculating Flow in Pipe Expansion”. Transactions of the ASME, Journal of Fluids Engineering, Vol. 117, pp. 417–423.
[16] Hsieh, W.D., K.C. Chang. (1998). “Calculation of Wall Heat Transfer in Pipe-expansion Turbulence Flows”. International Journal of Heat and Mass Transfer, Vol. 43, pp. 144-131.
[17] Abe, K., Kondoh, T., Nagano, Y. (1994). “A New Turbulence Model for Predicting Fluid Fow and Heat Transfer in Separating and Reattaching Flows I: Flow Field Calculations”. International Journal of Heat and Mass Transfer, Vol. 37, pp. 139-151.
[18] Launder, B.E., Sharma, B.I. (1974). “Application of the Energy-dissipation Model of Turbulence to the Calculation of Flow Near a Spinning Disc”. Letters in Heat and Mass Transfer, Vol. 1, pp. 131–138.
[19] Weigand, B., Ferguson, J. R., Crawford, M. E. (1997). “An Extended Kays and Crawford Turbulent Prandtl Number Model”. International Journal of Heat and Mass Transfer, Vol. 40, pp. 4191-4196.
[20] Jischa, M., Rieke, H. B. (1982). “Modeling Assumptions for Turbulent Heat Transfer”. Proc. Seventh Int. Heat Transfer Conference of Muchen, Vol. 3, pp. 257-262.
[21] So, R. M. C., Sommer T. P. (1994). “A Near-wall Eddy Conductivity Model for Fluids with Different Prandtl Numbers”. International of Heat and Mass Transfer, Vol. 116, pp. 884-854.
[22] Mohamad, G. Ghorab. (2013). “Cooling Performance and Flow-field Analysis of a Hybrid Scheme with Different Outlet Configurations”. Thermal Engineering, Vol. 61, pp. 799-816.
[23] Mohamad, G. Ghorab. (2014). “Film Cooling Effectiveness and Heat Transfer Analysis of a Hybridscheme with Different Outlet Configurations”. Thermal Engineering, Vol. 63, pp.  200-217.
[24] Montomoli, F., D’Ammaro, S. Uchida. (2013). “Numerical and Experimental Investigation of a New Film Cooling Geometry with High P/D Ratio”. International Journal of Heat and Mass Transfer, Vol. 66, pp. 366–375.
[25] Cun-liang Liu, Hui-ren Zhu, Zong-wei Zhang, Du-chun Xu. (2012). “Experimental Investigation on the Leading Edge Film Cooling of Cylindrical and Laidback Holes With Different Hole Pitches”. International Journal of Heat and Mass Transfer, Vol. 55, pp. 6832–6845.
[26] Cun-liang Liu, Jin-long Liu, Hui-ren Zhu, A-sai Wu, Yi-hong He, Zhi-xiang Zhou. (2015). “Film Cooling Sensitivity of Laidback Fan-shape Holes to Variations in Exit Configuration and Mainstream Turbulence Intensity”. International Journal of Heat and Mass Transfer, Vol. 89, pp. 1141–1154.