نوع مقاله : علمی- ترویجی

نویسندگان

1 دانشجوی دکتری، پژوهشگاه هوافضا وزارت علوم تحقیقات و فناوری، تهران، ایران

2 استادیار، پژوهشگاه هوافضا، وزارت علوم تحقیقات و فناوری، تهران، ایران

چکیده

این مقاله شامل بررسی و مقایسه روش‌های محاسبه ضریب انتقال حرارت جابجایی در محفظه احتراق و در نازل همگرا-واگرا می‌باشد. به این منظور، ابتدا تاریخچه‌ای از روش‌های مختلف محاسبه ضریب انتقال حرارت جابجایی بیان شده و سپس جریان داخلی نازل به روش صریح مک-کورمک حل شده است. روش‌های بارتز، استانتون، پریکسورن و آدمی در بین روش‌های مطرح این حوزه انتخاب شده و با استفاده از CFD در نازل باتس (BATES) مقایسه شده است. در ادامه، در یک موتور سوخت جامد، با در نظر گرفتن پارامترهای جریان در محفظه موتور، ضریب انتقال حرارت جابجایی محاسبه و نشان داده شده که هر چه به سمت نازل حرکت شود، با افزایش سرعت، ضریب انتقال حرارت افزایش می‌یابد. این بررسی نشان می‌دهد که ماکزیمم ضریب انتقال حرارت جابجایی در روش‌های تحلیلی در گلوگاه نازل اتفاق می‌افتد، در حالیکه آنالیز CFD نشان می‌دهد که حداکثر ضریب انتقال حرارت در بالادست نازل است. اگرچه CFD از دقت بالاتری برای محاسبه ضریب انتقال حرارت، نسبت به روش‌های تحلیلی، برخوردار است، اما نیازمند زمان محاسباتی بسیار است. بنابراین، در طراحی اولیه می‌توان از روش‌های تحلیلی به علت زمان محاسبات سریع استفاده نمود، به ویژه در گلوگاه. در نهایت، با بررسی انجام شده، نشان داده شد که راهکار ابتکاری ترکیب روش‌های آدمی و بارتز کمترین خطا را نسبت به CFD دارد.

کلیدواژه‌ها

عنوان مقاله [English]

Investigation of Calculation Methods for Convective Heat Transfer Coefficient in Combustion Chambers and in Converging-Diverging Nozzles

نویسندگان [English]

  • Mohammad Razmjooei 1
  • Zaheer Sabohi 2

1 ph.D student. Aerospace Research Institute, Ministry of Science, Research and Technology, Tehran, Iran

2 Assistant Professor, Aerospace Research Institute, Ministry of Research and Technology, Tehran, Iran

چکیده [English]

This paper reports a review and comparison of the methods used for calculating convective heat transfer coefficient in combustion chambers and in diverging-converging nozzles. Therefore, a history of applying different methods for calculating the convective heat transfer coefficient is explained first. Then, the nozzle flow is numerically solved, using the explicit McCormack method. In a Bates nozzle, The methods of Bartz, Stanton, Preiskorn, and Adami were selected among the proposed methods and were compared with CFD. Convective heat transfer coefficient of a solid fuel engine was calculated by taking into account the flow parameters in the engine chamber. Consequently, it was found that as wet move to the nozzle, heat transfer coefficient increases with velocity of the flow. This results revealed that in analytical methods, the maximum convective heat transfer coefficient occurs in the nozzle throat, while CFD results show that the maximum occurs upstream of the nozzle throat. These methods require less computational time than CFD, however CFD has to be considered more accurately. As a result, during a preliminary design procedure, the much faster and slightly less precise method can be used, in particular at the throat where the relative difference between the methods is quite low. Finally, it was shown that the innovative approach of combining Adami and Bartz methods has the lowest possible error, compared to the CFD.

کلیدواژه‌ها [English]

  • Convective Heat Transfer Coefficient
  • Combustion Chamber
  • Converging-Diverging Nozzle
  • Internal Flow
  • Throat
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