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بررسی آزمایشگاهی اثر زبری بستر بر روی توزیع سرعت در بدنه جریان غلیظ
عنوان (انگلیسی): Laboratory Investigation of Bed Roughness Effects on Velocity Distribution in the Body of Gravity Currents
نشریه: پژوهش آب ايران
شماره: پژوهش آب ايران (دوره: ۱۰، شماره: ۳)
نویسنده: کاهه، مهدی ، قمشی، مهدی ، موسوی جهرمی، سید حبیب
کلیدواژه‌ها : ناحیه جت و دیواره ، توزیع سرعت ، جریان غلیظ ، زبری بستر
کلیدواژه‌ها (انگلیسی): Gravity Current , Jet and Wall Region , Bed Roughness , Velocity Distribution
چکیده:

در این تحقیق اثر زبری بستر بر روی توزیع سرعت در بدنه جریان غلیظ مورد به عنوان دو عامل موثر مطالعه قرا گرفت. برای این‌منظور آزمایشاتی به صورت جریان غلیظ نمکی در 3 دبی ورودی 7‎/0،‏ 1 و 3‎/1 لیتر بر ثانیه و محدوده شیب 0 تا 2‎/2 درصد صورت پذیرفت. برای زبر کردن بستر از ذرات شن طبیعی با اندازه‌های 0،‏ 4،‏ 7،‏ 12 و 16 میلی‌متر استفاده شد. همچنین به منظور بررسی اثر تغییرات غلظت جریان ورودی بر مشخصات جریان غلیظ،‏ از سه غلظت 10،‏ 16 و 20 گرم بر لیتر استفاده شد. نتایج نشان می‌دهد که ارتفاع سرعت حداکثر در پروفیل سرعت بدنه با افزایش زبری کف افزایش می‌یابد. ارتفاع نسبی محل سرعت حداکثر hm/h در ks/h برابر مقدار ثابت 3‎/0 است و با افزایش زبری نسبی ks/h،‏ ارتفاع نسبی محل سرعت حداکثر hm/h ،‏ به سمت عددی ثابت 65‎/0 همگرا می‌شود. نتایج نشان می‌دهد که زبری مهمترین عامل در توزیع سرعت درناحیه جت و دیواره می‌باشد به‌طوری‌که بررسی تشابه توزیع سرعت بدنه در جریان غلیظ در ناحیه جت و دیواره،‏ به ترتیب با توزیع‌های نیمه گوسی و توانی،‏ نشان می‌دهد که ضرائب توزیع سرعت در بدنه با افزایش زبری بستر تغیر می‌کند.

چکیده (انگلیسی):

The hydraulic properties of gravity currents are affected by slope and bed roughness. In this study to determine the bed roughness effect on the velocity distribution of gravity currents body, a series of gravity currents experiments was performed on beds with rough natural element size of 4, 8, 12 and 15 mm. The experiments of saline gravity currents with three inflow discharges equal to 0.7, 1 and 1.3 (lit/s) and three concentrations of 10, 16 and 20 (gr/lit) were carried out on slope beds from about 0 to 2.2%. In all experiment, the velocity distribution in body of gravity current was acquired by an Ultra-Sonic Doppler Velocimeter device. The results show that by increasing of bed roughness size, the height of maximum velocity location in the velocity distribution of gravity currents body rise up. The relative height of maximum velocity location , when , is equal to 0.3, and by increasing , the value of converge to constant of 0.65. Also, the results of this study show that bed roughness is one of the most important factor on velocity distribution. The similarity of the velocity distribution, in both jet and wall flow region, by Semi-Gaussian and power distribution equations show that the coefficient of velocity distribution is varied by increasing bed roughness.The hydraulic properties of gravity currents are affected by slope and bed roughness. In this study to determine the bed roughness effect on the velocity distribution of gravity currents body, a series of gravity currents experiments was performed on beds with rough natural element size of 4, 8, 12 and 15 mm. The experiments of saline gravity currents with three inflow discharges equal to 0.7, 1 and 1.3 (lit/s) and three concentrations of 10, 16 and 20 (gr/lit) were carried out on slope beds from about 0 to 2.2%. In all experiment, the velocity distribution in body of gravity current was acquired by an Ultra-Sonic Doppler Velocimeter device. The results show that by increasing of bed roughness size, the height of maximum velocity location in the velocity distribution of gravity currents body rise up. The relative height of maximum velocity location , when , is equal to 0.3, and by increasing , the value of converge to constant of 0.65. Also, the results of this study show that bed roughness is one of the most important factor on velocity distribution. The similarity of the velocity distribution, in both jet and wall flow region, by Semi-Gaussian and power distribution equations show that the coefficient of velocity distribution is varied by increasing bed roughness.The hydraulic properties of gravity currents are affected by slope and bed roughness. In this study to determine the bed roughness effect on the velocity distribution of gravity currents body, a series of gravity currents experiments was performed on beds with rough natural element size of 4, 8, 12 and 15 mm. The experiments of saline gravity currents with three inflow discharges equal to 0.7, 1 and 1.3 (lit/s) and three concentrations of 10, 16 and 20 (gr/lit) were carried out on slope beds from about 0 to 2.2%. In all experiment, the velocity distribution in body of gravity current was acquired by an Ultra-Sonic Doppler Velocimeter device. The results show that by increasing of bed roughness size, the height of maximum velocity location in the velocity distribution of gravity currents body rise up. The relative height of maximum velocity location , when , is equal to 0.3, and by increasing , the value of converge to constant of 0.65. Also, the results of this study show that bed roughness is one of the most important factor on velocity distribution. The similarity of the velocity distribution, in both jet and wall flow region, by Semi-Gaussian and power distribution equations show that the coefficient of velocity distribution is varied by increasing bed roughness.The hydraulic properties of gravity currents are affected by slope and bed roughness. In this study to determine the bed roughness effect on the velocity distribution of gravity currents body, a series of gravity currents experiments was performed on beds with rough natural element size of 4, 8, 12 and 15 mm. The experiments of saline gravity currents with three inflow discharges equal to 0.7, 1 and 1.3 (lit/s) and three concentrations of 10, 16 and 20 (gr/lit) were carried out on slope beds from about 0 to 2.2%. In all experiment, the velocity distribution in body of gravity current was acquired by an Ultra-Sonic Doppler Velocimeter device. The results show that by increasing of bed roughness size, the height of maximum velocity location in the velocity distribution of gravity currents body rise up. The relative height of maximum velocity location , when , is equal to 0.3, and by increasing , the value of converge to constant of 0.65. Also, the results of this study show that bed roughness is one of the most important factor on velocity distribution. The similarity of the velocity distribution, in both jet and wall flow region, by Semi-Gaussian and power distribution equations show that the coefficient of velocity distribution is varied by increasing bed roughness.

فایل مقاله : ‏67 دریافت تاكنون
صاحب امتیاز:
دانشگاه شهرکرد
مدیر مسئول:
دکتر حسين صمدی
سردبیر:
دکتر منوچهر حيدرپور
مدیر داخلی:
دکتر محمدعلی نصراصفهانی