Experimental study on the acoustic field caused by the interference of supersonic jet with a perforated plate—The optical measurement of sound absorption

2019 ◽  
Vol 146 (4) ◽  
pp. 3000-3000
Author(s):  
Yo Murata ◽  
Kaku Murayama ◽  
Tatsuya Ishii ◽  
Koji Okamoto ◽  
Hirofumi Daiguji ◽  
...  
Akustika ◽  
2020 ◽  
Vol 36 (36) ◽  
pp. 22-24
Author(s):  
Anatoly Kochergin ◽  
Valeeva Ksenia

The paper considers an acoustic field created by a supersonic jet (CES) of a rocket engine freely flowing into flooded space. The acoustic field was presented in the form of a diagram of noise isobars, from which it can be seen that the acoustic field is formed by two effective noise sources: the nearest one, lying at a distance of 5-10 calibers from the nozzle cut and the far one, lying at a distance of 15-30 calibers from the nozzle cut.


Author(s):  
Vladimir Golubev ◽  
Anstasios Lyrintzis ◽  
Reda R. Mankbadi ◽  
Konstantin A. Kurbatskii ◽  
Barrett Guenthoer

2018 ◽  
Vol 43 (17) ◽  
pp. 8524-8533 ◽  
Author(s):  
Quan Li ◽  
Xuxu Sun ◽  
Shouxiang Lu ◽  
Zhi Zhang ◽  
Xing Wang ◽  
...  

Author(s):  
A’rasy Fahruddin

HHO merupakan gas hasil elektrolisa air yang dapat digunakan sebagai bahan bakar tambahan pada motor bakar. Penelitian ini bertujuan mengetahui karakteristik generator HHO menggunakan elektroda pelat berlubang. Elektroda yang dipakai berupa pelat aluminium dengan ukuran 60 x 60 x 0.5 mm3 dengan variasi tanpa lubang, 4 lubang, 6 lubang, dan 9 lubang. Masing-masing lubang berdiameter 4 mm. Variasi tegangan input 3,5; 6; 7,5; 9 Volt. Karakteristik yang diuji meliputi daya input, debit, dan efisiensi generator HHO. Hasil yang didapatkan dari penelitian ini adalah bahwa debit gas HHO yang terbesar dihasilkan dengan elektroda 9 lubang yaitu sebesar 5,77 cc/min dengan daya input 4,59 Watt. Sedangkan efisiensi generator tertinggi juga dihasilkan dengan elektroda 9 lubang yang mampu mencapai efisiensi 63,16 % dengan daya input 0,52 Watt.


Materials ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 120 ◽  
Author(s):  
Marta Kałuża ◽  
Jacek Hulimka ◽  
Jan Kubica ◽  
Marcin Tekieli

In typical technical applications, steel components are usually connected by welding or with mechanical connectors. An alternative solution, typical in the aviation and automotive industry, but not widespread in engineering structures, is to join thin sheet metal using adhesives. The article presents an experimental study of adhesive joints used in overlap connections subjected to static tension. A methacrylate adhesive, selected experimentally from a range of adhesives, which combines the optimum strength and strain properties, was tested. The laboratory tests were carried out on double-lap specimens made of high-strength Domex 700 steel. On the basis of the experimental results, the behavior of the specimens and their failure mechanism, depending on the anchorage lengths used (200, 300 and 400 mm), are described. The tests confirmed the effectiveness of the selected methacrylate adhesive in a practical application. It was shown that with the appropriate anchorage length (adequate to the type of steel components and the joint geometry) between 300 and 400 mm, the capacity of the adhesive joint is higher than the capacity of a single steel component. Two types of specimen behavior were recognized: Quasi-brittle, which occurs at the anchorage length of 200 mm, and ductile, observed for 300 mm and 400 mm anchoring. In addition, thanks to the optical measurement method used, a detailed strain distribution on the specimen surface was determined. The data will be used for subsequent validation of an analytical and numerical model.


Author(s):  
Himanshu Tyagi ◽  
Rui Liu ◽  
David S.-K. Ting ◽  
Clifton R. Johnston

The study of vortex shedding from a sphere assumes an important role because of its relevance to numerous aerodynamic and hydrodynamic applications. Parameters such as coefficient of drag and static pressure distribution are largely influenced by vortex shedding, and it is found by past studies that the freestream turbulence can interact and alter the vortex formation and shedding drastically. Most of these studies, however, were conducted in the low Reynolds number regime and the vortex shedding results had been described only qualitatively. To better understand the aerodynamics of a sphere in turbulent flow, an experimental study was initiated in a low speed wind tunnel to quantify the vortex shedding characteristics. The Reynolds number of the flow, based on the diameter of the sphere (d), was set at 3.3 × 104, 5 × 104 and 6.6 × 104 by varying the mean flow velocity. The sphere was placed at 20D (= 7.5d) downstream from a perforated plate, where D = 37.5 mm is the size of the holes in the perforated plate, uniquely designed for generating near-isotropic turbulence. Hot-wire measurements were taken at 10D (= 3.75d), 20D (= 7.5d) and 30D (= 11.25d) downstream of the sphere in absence and presence of the perforated plate. The vortex shedding frequency was deduced from the instantaneous flow velocity data.


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