دانلود رایگان مقاله لاتین مدل صیقلی از لحاظ فیزیکی از سایت الزویر
عنوان فارسی مقاله:
مدل صیقلی از لحاظ فیزیکی مدرن و ارتقاء یافته برای افزودنی حباب جت هوا
عنوان انگلیسی مقاله:
An Enhanced Physically Based Scour Model for Considering Jet Air Entrainment
سال انتشار : 2016
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مقدمه انگلیسی مقاله:
1. Introduction
Many empirical engineering methods are available to estimate scour formation downstream of plunging jets. Nevertheless, such empirical formulations are site-specific and not applicable to a wider range of cases [1]. As a matter of fact, the scouring process at plunge pool floors is a result of the interactions of the three phases involved: water, rock, and air. Moreover, the highly turbulent nature of the flow and the resulting pressure fluctuations on the water-rock interface and inside rock fissures make appropriate scaling impossible in hydraulic modeling. Therefore, the applicability of Froude-based reduced-scale models is extremely limited. The Comprehensive Scour Model (CSM) was first proposed by Bollaert and Schleiss [2,3]. It has the advantage of considering the physical phenomena involved in the scour of the rock impacted by plunging water jets. The model was developed as a result of experiments with plunging jets of near-prototype velocities impacting on closed-end and open-end fissures at the pool bottom. As such, the model reproduces the characteristics of the pressure signals of prototype jets, thus minimizing scale effects. Furthermore, Manso et al. [4,5] proposed adaptations to the CSM that took into account the influence of the pool bottom geometry and the resulting induced flow patterns. The present study proposes adaptations to the CSM in order to consider the effect of jet air entrainment as obtained by a systematic experimental campaign. The experimental setup and test program are presented in detail by Duarte [6]. The large facility was built at the Laboratory of Hydraulic Constructions of the École polytechnique fédérale de Lausanne. The vertical jets were issued from a dj = 72 mm diameter outlet nozzle, where compressed air was added to the water flow. Near-prototype air-water jet velocities up to 22.1 m·s–1 were reproduced. The jets impinged into a 3 m diameter cylindrical basin. Plunging and submerged jets were tested. The pool depths, Y, were 30 cm, 50 cm, and 80 cm deep, resulting in relative pool depths Y/dj of 4.2, 6.9, and 11.1, respectively. On the bottom of the pool, a metallic system to represent fully
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کلمات کلیدی:
Physically Based Model for Evaluation of Rock Scour ... - ResearchGate https://www.researchgate.net/.../37445945_Physically_Based_Model_for_Evaluation_of... Therefore, a model to evaluate the ultimate depth and time evolution of scour ... An Enhanced Physically Based Scour Model for Considering Jet Air Entrainment. Influence of Air Entrainment on Rock Scour ... - Semantic Scholar https://pdfs.semanticscholar.org/c782/39daac4f2db05feec21f6f4ed96322232017.pdf by RXM DUARTE - 2014 - Cited by 5 - Related articles Two numerical models reproduce the dynamic ejection of rock blocks. ... developed previously in the framework of this research at the LCH, in order to consider ... Keywords: Air entrainment, rock scour, plunge pool, high-velocity jets, fluid- ... Sprayed Concrete Lined Tunnels - Page 1769 - Google Books Result https://books.google.com/books?isbn=0415365465 Alun Thomas - 2008 - Technology & Engineering As disintegration of the jet at the lip of the flip bucket in the model is realized weakly ... Moreover eroded materials removed from the scour hole may be transported ... The degree of air entrainment and the disintegration of the jet occur in a very ... with flip buckets differ, as they do not consider the effective parameters in jet ... Mechanism of rock-bed scour due to impinging jet www.tandfonline.com/doi/pdf/10.1080/00221680903565879 by A Li - 2010 - Cited by 10 - Related articles The physical mechanism of rock disintegration and scour pool forming are analysed herein by considering the frac- ture-structure of ... Schleiss (2003, 2005) studied the effect of air entrained in the water and proposed the two-phase transient hydraulic model. ..... Considering the three surrounding fracture cells (i.e. j ¼ 1, 3),. scour and dynamic pressure of impinging jets with and without aeration vzb.baw.de/publikationen/tc213/0/LS_21.pdf by Z DONG - Related articles impinging jets with air entrainment would weaken scour capacity of the jet; ... the model and prototype data, we can find the maximum error is up high to ... whether we have been poorly considering the other factors that stand for important ...
