کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
656354 1458042 2016 12 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Modeling of void fraction covariance in two-phase flows with phase change
ترجمه فارسی عنوان
مدلسازی کوواریانس کسری بی اعتبار در جریان های دوفازی با تغییر فاز
کلمات کلیدی
کوواریانس کسری بی اعتبار؛ ضخامت لایه حباب؛ تغییر فاز؛ کشیدن سطحی؛ سرعت نسبی؛ جریان دو فاز
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی جریان سیال و فرایندهای انتقال
چکیده انگلیسی


• Improvement of the area-averaged local relative velocity in gas-dispersed flow.
• Covariance in area-averaging total, group-1, and group-2 void fraction are addressed.
• Boiling and adiabatic condensing/flashing flows are considered.
• Easily implemented correlations are proposed for important void fraction covariances.

The void fraction covariance, which accounts for non-uniformity in the void fraction distribution in the one-dimensional two-fluid model, has been shown to be critical for accurate prediction of the area-averaged interfacial drag force. Defined as the ratio of area-averaged square of void fraction to the square of the area-averaged void fraction, the void fraction covariance, which historically has been treated as unity, is analyzed for gas-dispersed flows undergoing phase change. The covariance is shown to be very large in subcooled boiling where the void fraction is highly non-uniform, which highlights the benefit of the bubble layer thickness averaged two-fluid model. In condensing and flashing flow the void fraction covariance is shown to be significant, having a very large impact on the interfacial drag force as the void fraction increases. The void fraction covariance is studied for its impact on the classical area-averaged two-fluid model, bubble-layer averaged two-fluid model, and area-averaged multiple bubble group two-fluid model. A simple set of correlations are proposed for easy implementation into the existing drag equations, and are shown to agree very well with experimental data.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: International Journal of Heat and Mass Transfer - Volume 100, September 2016, Pages 231–242
نویسندگان
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