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
 
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