Abstract




 
   

IJE TRANSACTIONS A: Basics Vol. 32, No. 1 (January 2019) 137-145    Article in Press

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  ON NUMERICAL INVESTIGATION OF SEMI-EMPIRICAL RELATIONS REPRESENTING LOCAL NUSSELT NUMBER AT LOWER NOZZLE-TARGET SPACING’S
 
S. Mohd Umair, N. P. Gulhane, A. R. A. Al-Robaian and S. A. Khan
 
( Received: November 16, 2018 – Accepted in Revised Form: January 03, 2019 )
 
 

Abstract    Examining the cooling rate using impingement of air jet finds a wide application in electronic packaging and micro-scale fluid heat interaction systems, While the prediction of Nusselt profile at low nozzle-target spacing is a big issue. The plot of area average Nusselt number magnitude against the nozzle-target spacing (Z/d) shows a gradual decrement in the profile upto Z/d = 1 and beyond that is steady. The present work aims in anticipating the profile of Nusselt number using semi-empirical relations. These semi-empirical relations are derived using using regression analysis which is carried out between Re, Z/d and local Nusselt number.The data required for regression are obtained through computation. Numerical simulations are accomplished for different impinging and geometric parameters. The semi-empirical power law relations are correlated between Z/d and Re. These are predicted differently for four distinct region of heat sink (stagnant point, near jet region, far jet region, near wall region). The developed correlations are found to bear negative exponent with Z/d and positive exponent with Re. The negative power of r/d and Z/d varies from 0.23 – 0.64 and 0.0025 – 0.38, respectively, While the exponents of Re varies in the positive range of 0.4-0.76

 

Keywords    Local Nusselt Number, Prandtl Number, Nozzel, Numerical Simulation, Heat Sink, Gamma–theta Model

 

چکیده   

بررسی میزان خنک کننده با استفاده از نفوذ جت هوا، کاربرد وسیعی در بسته بندی های الکترونیکی و سیستم های متقابل حرارتی مایع در مقیاس کوچک را در بر می گیرد، در حالی که پیش بینی پروفیل Nusselt در فاصله بین فاصله بین هدف نازل یک موضوع بزرگ است. قطر محدوده متوسط Nusselt بزرگ در برابر فاصله بین هدف نازل Z / D)) نشان می دهد کاهش تدریجی در مشخصات تا Z / d = 1 و فراتر از آن ثابت است. هدف این مقاله پیش بینی پروفیل عدد نوستل با استفاده از روابط نیمه تجربی است. این روابط نیمه تجربی با استفاده از تحلیل رگرسیون که بین Re، Z / d و شماره Nusselt محلی انجام می شود، به دست آمده است. داده های مورد نیاز برای رگرسیون از طریق محاسبه به دست می آیند. شبیه سازی عددی برای پارامترهای مختلف و پارامترهای هندسی انجام می شود. روابط قانون قانون نیمه تجربی بین Z / d و Re رابطه دارد. این ها برای چهار منطقه مجزا گرمادهی (نقطه رکود، نزدیکی جت منطقه، منطقه جت دور و نزدیک منطقه دیوار) متفاوت است. همبستگی های توسعه یافته نشان دهنده میزان منفی با Z / d و مثبت با Re است. قدرت منفی r / d و Z / d به ترتیب از 0.23 - 0.64 و 0.0025 - 0.38 در تغیر است، در حالیکه شاخص های Re در محدوده مثبت 0.4-0.76 تغیر می نمایند.

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