List of Articles Cavitation

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  1 - Reduction of cavitation in the hydraulic jump pond of the cooling tower by stepping the end sill
  Ehsan Behjati Amir Khosrojerdi Ali Saremi
  10.30495/wsrcj.2023.68060.11307
  Introduction: Cooling towers are an important and vital part of industrial units that are used for water cooling that is used in the cooling processes of systems in power plants, refineries and other industrial units. One of the important components of towers is the rel More

  Introduction: Cooling towers are an important and vital part of industrial units that are used for water cooling that is used in the cooling processes of systems in power plants, refineries and other industrial units. One of the important components of towers is the relaxation pool, the main role of which is to collect water for transfer to the system, the number of suction pools is usually designed according to the number of each pump. One of the important tasks of the relaxation pool structure in this structure is energy dissipation. In this regard, usually in this pond, the hydraulic structure of the hydraulic jump is used for energy dissipation. In the hydraulic jump process, the current changes from supercritical to subcritical. This causes a loss of flow energy. In cooling ponds, downstream slope is usually used to control the hydraulic jump. In cooling ponds, downstream slope is usually used to control the hydraulic jump. Various studies have shown that using stairs instead of ramps can greatly increase energy loss in the relaxation pool. In this study, by replacing the stepped surface with a sloping surface, the effects of this process on flow lines as well as its effects on cavitation are investigated.Method: In this research, the Fluent numerical model is used to numerically model the flow around the structure of the cooling tower calm pond. In this regard, the dimensions of the relaxation pool in the concrete cooling tower are very important from an engineering point of view and should be designed in such a way that the operating conditions of the pumps are safe. Existence of high velocities and pressure drop in the dischargers causes serious problems related to the occurrence of cavitation phenomenon. Since modeling a physical model usually requires a lot of time and money, a numerical model calibrated with laboratory data was used to follow this research. In this study, due to the recognition of destructive eddy currents created around the lower valve when the valve is opened, hydraulic optimization of the relaxation pool and the appropriate width of the relaxation pool in refineries is one of the objectives of this study.Results: The study of increasing the flow in numerical modeling showed that with increasing the flow due to the increase in energy loss due to the stepping of the end threshold, the water height in the calm pool decreases significantly. This drop is estimated at an average of about 67%. Also, the results of water level profiles showed that the threshold of the end of the pond in a stepped manner, has a greater drop than the sloping conditions. Also, in exchange for higher discharges, this drop will move to higher values. Therefore, in the numerical model, the flow conditions on the stairs were analyzed at minimum and maximum flow. Regarding the study of pressure drop in the relaxation pool, it can be stated that the development of flow in the pool section based on increasing the width and height of the duct increases the amount of velocity during the discharge, which has led to pressure drop. Conclusion: The results of the study of cavitation number along the pond indicate that for the ratio of water depth to the width of the pond less than 1.82, the possibility of cavitation during the pond will be reduced. Also, depleting blocks in the pond have a positive effect on improving hydraulic performance, which leads to increased energy dissipation and jump stabilization, reduced speed, length, height of hydraulic jump and also reduces the risk of cation compared to the case without depleting blocks. Manuscript profile
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  2 - تاثیر استغراق خروجی تخلیه‌کننده تحتانی بر میزان هوادهی بین دو دریچه اضطراری و سرویس در سدهای بلند
  مهدی جورابلو مهدی فولادی پناه فاطمه ناصری حامد سرکرده مرتضی ماروسی
  استفاده از تونل های تخلیه کننده تحتانی به منظور تخلیه و نیز تنظیم سطح آب مخزن از اهمیت بسیار زیادی در مدیریت عملکرد سد برخوردار هستند. میزان بازشدگی دریچه سرویس و دریچه اضطراری در تونل ها نقش مهمی در تغییرات فشار، سرعت و ضریب آبگذری و در نهایت عملکرد تونل دارند. در این More

  استفاده از تونل های تخلیه کننده تحتانی به منظور تخلیه و نیز تنظیم سطح آب مخزن از اهمیت بسیار زیادی در مدیریت عملکرد سد برخوردار هستند. میزان بازشدگی دریچه سرویس و دریچه اضطراری در تونل ها نقش مهمی در تغییرات فشار، سرعت و ضریب آبگذری و در نهایت عملکرد تونل دارند. در این تحقیق میزان هوادهی جریان بین دریچه سرویس و اضطراری در دو مدل فیزیکی سد کارون 4 و قیزقلعه سی با شرایط پایاب آزاد و مستغرق مورد بررسی قرار گرفت. در این راستا ضریب هوادهی برای هر مدل به صورت آزمایشگاهی اندازه گیری شد. همچنین به منظور بررسی نوسانات فشار حاصل از جت خروجی از دریچه ها در محل حوضچه آرامش، شبیه سازی عددی به کمک نرم افزار Flow3D انجام شد. نتایج نشان داد که استغراق خروجی اثر کاهنده به میزان 50 درصد بر هوادهی جریان دارد. این بدان معنی است که چنانچه تخلیه کننده در خروجی مستغرق باشد، امکان رخداد پدیده کاویتاسیون بیشتر خواهد بود و در نتیجه نیاز به سازه هوارسان با ابعاد بزرگتر می باشد. همچنین مشاهده شد با انجام هوادهی در جت میزان نوسانات در کف حوضچه کاهش پیدا می کند و امکان رخداد کاویتاسیون نیز از بین می رود.   Manuscript profile
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  3 - Design And Numerical Analysis of Propeller for Khazar Dredger
  احد عابدینی سهیل اسدی
  In this article, using a central composite design response surface methodology is that design of the optimal propeller geometry for khazar dredger will be discussed. B_Wageningen standard series is designed propeller-type licenses. To verify the performance and Check no More

  In this article, using a central composite design response surface methodology is that design of the optimal propeller geometry for khazar dredger will be discussed. B_Wageningen standard series is designed propeller-type licenses. To verify the performance and Check non-occurrence of cavitation ,the propeller designed using Computational Fluid Dynamics, numerical modeling and compare with B_Wageningen series. The results show the ability of response surface methodology in finding the optimal geometry propeller. Numerical solution of fluid flow, to prove non-occurrence of cavitation in the propeller designed for kazar dredger. Manuscript profile
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  4 - Design, Fabrication, and Assessment of a Hydrodynamic Reactor for Biodiesel Production
  Kimia Taki Bahram Hosseinzadeh Samani
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  5 - Physical Modelling of Self-Aeration in a Cavitating Sudden PIPE Expansion Flow
  H Hajikandi
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  6 - The Effect of Massage with Cavitation and Green Coffee on Leptin and ATGL Enzyme in Sedentary Obese Females
  Samaneh Zare Javad  Ramezani Somayeh   Khosravanian
  The prevalence of overweight and obesity is increasing in worldwide. Obesity is the root cause of many diseases, including chronic diseases such as diabetes, fatty liver, and cardiovascular diseases. Overweight and obesity is a complex process that is influenced by soci More

  The prevalence of overweight and obesity is increasing in worldwide. Obesity is the root cause of many diseases, including chronic diseases such as diabetes, fatty liver, and cardiovascular diseases. Overweight and obesity is a complex process that is influenced by social, cultural, behavioral, physiological, genetic and epigenetic factors. Therefore, the aim of this research was to determine the effect of 8 weeks of massage with cavitation device and green coffee supplement consumption on leptin hormone and ATGL enzyme levels in obese women. Sixty obese women with age range (20-35 years) and average body mass index (32 kg/m2) participated voluntarily in this research. Subjects were randomly divided into equal four groups; control group, cavitation massage group, green coffee supplement group, and cavitation massage with green coffee supplement groop (N= 4*15). Green coffee capsules with a dose of 200 mg were used. Training groups were massaged with a cavitation device for eight weeks, five sessions a week and according to the massage program. At the beginning of the study, fasting blood sampling was done from all groups. The sample was centrifuged at 4000 rpm for about 20 minutes, and after, the serum was prepared, the samples were immediately frozen at -70°C until the time of testing. The leptin hormone and ATGL enzyme levels of the subjects were measured by ELISA laboratory method, and at the end of eight weeks, blood sampling was done again with the same conditions as before, and the leptin hormone and ATGL enzyme levels of the subjects were measured again. Two-way analysis of variance test at 95% confidence level were used to compare the data and investigate the effect of supplementation and massage. Based on the results of this research, 8 weeks of massage with cavitation device and green coffee supplement in all treatment groups caused a significant decrease in leptin hormone level and a significant increase in ATGL enzyme level in obese women (P<0.05). In the simultaneous intervention group, the most changes were observed in leptin hormone and ATGL enzyme levels (p=0.0001). Massage with a cavitation device and green coffee supplement each have an effect on the level of leptin hormone and ATGL enzyme, but according to the results, the intervention of these two has more effects. Manuscript profile