کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
657647 1458072 2014 9 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Analyzing guard-heating to enable accurate hot-film wall shear stress measurements for turbulent flows
ترجمه فارسی عنوان
آنالیز حرارت محافظ برای فعال کردن اندازه گیری های دقیق برشی دیوار داغ فیلم برای جریان های آشفته
کلمات کلیدی
آشفتگی، استرس برشی دیوار، حسگرهای حرارتی محافظ، آنمیومتری حرارتی، روش های تجربی، توسعه سنسور، نوسانات، انتقال حرارت متصل، تجزیه و تحلیل ابعادی، تحلیل عددی، مدلسازی آشفتگی، کنترل جریان فعال
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی جریان سیال و فرایندهای انتقال
چکیده انگلیسی

In this paper we examine guard-heated hot-film sensors for the measurement of wall shear stress fluctuations in turbulent flows, using analytical and numerical techniques. The new thermal sensor designs proposed here, seek to eliminate the most severe source of error in conventional single-element hot-film sensors – which is indirect heat transfer to the fluid flow through the solid substrate. Published studies of the single-element hot-film show that a significant portion of the heat generated in the hot-film travels through the substrate before reaching the fluid, which causes spectral and phase errors in the wall shear stress signal and can drastically reduce the spatial resolution of the sensor. In addition, heat conduction parallel to the surface, within the fluid near the sensor edges, can produce significant errors when sensors are made smaller to improve spatial resolution. Here we examine the effectiveness of forcing zero temperature gradient at the edges of the hot-film in eliminating these errors. Air and water flow over such guard-heated sensors are studied numerically to investigate performance and signal strength of the guard-heated sensors. Our results show, particularly for low-conductivity fluids such as air, that edge guard-heating needs to be supplemented by a sub-surface guard-heater. With this two-plane guard-heating, a strong non-linearity in the standard single-element designs can be corrected, and substrate conduction errors contributing to spectral distortion and phase errors can be eliminated.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Journal of Heat and Mass Transfer - Volume 70, March 2014, Pages 835–843
نویسندگان
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