مقایسه نتایج مطالعات طراحی شده با روش های تاگوچی و فاکتوریل کامل در بررسی پارامتریک الگوی جریان حول آبشکن

در مطالعه پدیده‌های هیدرولیکی که تابع متغیرهای مختلف با سطوح تغییر متفاوت هستند، باید تمام ترکیبات ممکن (فاکتوریل کامل) آنها بررسی شود. اگر تعداد متغیرها اندک و شمار سطوح آنها کم باشد، انجام مطالعات به تعداد فاکتوریل کامل منطقی است. گاهی اوقات به دلیل مسائل اقتصادی و یا زمانی امکان انجام تعداد زیاد مطالعات وجود ندارد. روش تاگوچی که برای طراحی مطالعات به کار می‌رود، به جای استفاده از ترکیبات فاکتوریلی کامل از ترکیبات فاکتوریلی جزئی بهره می‌برد. این روش تعداد مطالعات را کاهش داده ضمن آنکه مقایسه موزون تمام متغیرها را تضمین می‌کند. هدف از پژوهش حاضر بررسی تاثیر استفاده از روش تاگوچی در مقدار بهینه بدست آمده برای پارامترهای طول آبشکن و موقعیت آن در قوس 90 درجه، در اعداد فرود مختلف، بر هیدرودینامیک جریان حول آبشکن است. همچنین مقایسه‌ای بین نتایج روش تاگوچی با روش فاکتوریل کامل در تعداد مطالعات، تعیین سطح بهینه هریک از پارامترها و زمان انجام مطالعات صورت گرفته است. بدین منظور برای هریک از پارامترهای طول و موقعیت آبشکن در قوس و عدد فرود، سه سطح تغییر درنظر گرفته شده است. مطالعات با روش‌های تاگوچی و فاکتوریل کامل طراحی شده و از مدل عددی ssiim برای انجام آن‌ها استفاده شده است. نتایج نشان داد روش تاگوچی، با 9 مطالعه به جای 27 مطالعه، با دقت خوب و نزدیک به نتایج طرح فاکتوریل کامل، ترکیب بهینه پارامترهارا پیش بینی نموده است. همچنین استفاده از روش تاگوچی منجر به کاهش حدود 66 درصدی در زمان مطالعات شده است.

Comparison of the results of studies designed by Taguchi and full factorial methods for parametric investigation of flow pattern around spur dike

Full factorial investigation is necessary in the study of the hydraulic phenomena which are function of different variables with different levels. It is logical to use the full factorial method when the number of variables and their levels are low. However, sometimes due to lack of time and shortage of financial restrictions, using the full factorial method is not possible. The Taguchi method, which is used for design of experiments, uses the fractional factorial instead of full factorial. This method not only decrease the number of studies but also guaranties the correlated comparison of all variables. In this paper the Taguchi method is used for finding the optimized hydraulic parameters like length and location of spur dike in different Froude Numbers in 90 degree bend. Furthermore, the comparison between the Taguchi method and full factorial is done for the number of investigations, finding the optimized level for each parameter and the time needed for study. In order to get the results, the parameters of length, location of spur dike in 90 degree bend, and the Froude Number are considered with three different levels. The SSIIM numerical model is applied to simulate the studies designed by Taguchi and full factorial methods. The results show that the Taguchi method, could predict the optimum parameters only with 9 studies whereas with full factorial method 27 studies was necessary. Also, using Taguchi method leads to more than 66% decrease in the total running time. For studies designed by Taguchi method, the optimum value of length of spur dike is the as one designed by Full factorial method. Also, the length of spur dike is the most effective parameter on flow pattern around spur dike and the position of spur dike and Froude Number are next in rank, respectively. These results are the same for two methods used to design of studies. Using 9 studies designed by Taguchi method, investigation of the effect of other parameter such as the angle of the spur dike is possible without changing the number of studies, whereas 81 studies should be done by full factorial method. Full factorial investigation is necessary in the study of the hydraulic phenomena which are function of different variables with different levels. It is logical to use the full factorial method when the number of variables and their levels are low. However, sometimes due to lack of time and shortage of financial restrictions, using the full factorial method is not possible. The Taguchi method, which is used for design of experiments, uses the fractional factorial instead of full factorial. This method not only decrease the number of studies but also guaranties the correlated comparison of all variables. In this paper the Taguchi method is used for finding the optimized hydraulic parameters like length and location of spur dike in different Froude Numbers in 90 degree bend. Furthermore, the comparison between the Taguchi method and full factorial is done for the number of investigations, finding the optimized level for each parameter and the time needed for study. In order to get the results, the parameters of length, location of spur dike in 90 degree bend, and the Froude Number are considered with three different levels. The SSIIM numerical model is applied to simulate the studies designed by Taguchi and full factorial methods. The results show that the Taguchi method, could predict the optimum parameters only with 9 studies whereas with full factorial method 27 studies was necessary. Also, using Taguchi method leads to more than 66% decrease in the total running time. For studies designed by Taguchi method, the optimum value of length of spur dike is the as one designed by Full factorial method. Also, the length of spur dike is the most effective parameter on flow pattern around spur dike and the position of spur dike and Froude Number are next in rank, respectively. These results are the same for two methods used to design of studies. Using 9 studies designed by Taguchi method, investigation of the effect of other parameter such as the angle of the spur dike is possible without changing the number of studies, whereas 81 studies should be done by full factorial method.