ارزیابی آزمایشگاهی تاثیر رژیم های همرفت طبیعی، ترکیبی و اجباری بر نرخ تبخیر از سطوح مواج آب

نوع مقاله : مقاله پژوهشی

نویسنده

استادیار، دانشکده مهندسی، دانشگاه بجنورد

چکیده

در این مطالعه با استفاده از اندازه‌گیری‌های آزمایشگاهی در دامنه گستردهای از نسبت ارتفاع به دوره تناوب موج، دمای آب و سرعت هوا در حالتی که نسبت عدد گراشف به مربع عدد رینولدز بین 01/0 و 100 در نظر گرفته شده است، نرخ تبخیر در رژیم‌های همرفت طبیعی، ترکیبی و اجباری با هم مقایسه شده است. نتایج اندازه‌گیری شده نرخ تبخیر برای سطوح مواج نشان می‌دهد که با افزایش سرعت هوا، نرخ تبخیر افزایش می‌یابد در حالی‌که با افزایش نسبت ارتفاع به دوره تناوب موج، نرخ تبخیر رفتار متفاوتی را با تغییرات رژیم جریان همرفت نشان می‌دهد. در رژیم همرفت طبیعی، با افزایش نسبت ارتفاع به دوره تناوب موج، سطح تماس آب و هوا و القای آشفتگی به لایه مرزی بخار افزایش می‌یابد که این موضوع باعث افزایش نرخ تبخیر می‌شود و نسبت‌های ارتفاع به دوره تناوب موج بالاتر از 15/0 متر بر ثانیه، باعث افزایش بیشتر نرخ تبخیر می‌گردد. در حالی‌که در رژیم‌های همرفت ترکیبی و اجباری، علاوه بر وجود مناطقی مشابه رژیم همرفت طبیعی که سبب افزایش نرخ تبخیر می‌شود در ترکیب خاصی از سرعت جریان هوا و پارامترهای سطح مواج، کاهش غیرمنتظره نرخ تبخیر دیده می‌شود.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

An Experimental Assessment on the Effects of Forced, Free and Mixed Convection Regimes on the Water Evaporation Rate in Surface Gravity Waves

نویسنده [English]

  • Amin Jodat
Mechanical Engineering Department, University of Bojnord, Assistant Professor
چکیده [English]

experimental measurements have been done over a wide range of wave parameters, water temperatures and air velocities in different convection regimes. The measurements were performed on a large heated wave flume equipped with a wind tunnel. The effects of forced, free and mixed convection regimes on the water evaporation rate in surface gravity waves have been investigated. The results show that wave motion on the water surface increases the rate of evaporation for all airflow regimes. In addition, results reveal the evaporation rate increases with air velocity but increasing of the wavy surface parameter, has different effects on the evaporation rate. For the free convection regime, the evaporation rate increases by increasing the wavy parameter. For forced and mixed convection regime at medium values of wave parameters, the leeward airflow structures, which form a barrier for the vertical transport of vapor, decrease evaporation rate. Results reveal that the effect of induced turbulence at the wavy interfacial surfaces on the water evaporation increment is more than the effect of interfacial area increment percentage. Results reveal that the effect of induced turbulence at the wavy interfacial surfaces on the water evaporation increment is more than the effect of interfacial area increment percentage.

کلیدواژه‌ها [English]

  • Gravity waves
  • forced convection
  • free convection
  • mixed convection
  • evaporation
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