Experimental study on the cavity dynamics in high-speed oblique water-entry

2018 ◽  
Vol 50 (4) ◽  
pp. 045511 ◽  
Author(s):  
Chen Chen ◽  
Qingpeng Ma ◽  
Yingjie Wei ◽  
Cong Wang
Keyword(s):  
Experimental Study ◽  
High Speed ◽  
Water Entry

Experimental study on oblique water entry of projectiles

2016 ◽  
Vol 30 (28) ◽  
pp. 1650348 ◽  
Author(s):  
Chenggong Zhao ◽  
Cong Wang ◽  
Yingjie Wei ◽  
Xiaoshi Zhang ◽  
Tiezhi Sun
Keyword(s):  
Experimental Study ◽  
Impact Velocity ◽  
High Speed ◽  
Transition Point ◽  
Water Entry ◽  
High Speed Photography ◽  
Initial Water ◽  
Before And After ◽  
Velocity Attenuation ◽  
Cavity Evolution

An experimental study of oblique water entry of projectiles with different noses has been conducted using high-speed photography technology. The images of the initial water entry impact, cavity evolution, and the closure and shedding of vortices of cavity are presented in the paper. The results reveal that for high-speed oblique water entry (the initial impact velocity [Formula: see text][Formula: see text]50 m/s), the cavity attached to the projectile is symmetrical and free from the influence of gravity. The shedding of the water–vapor–air mixture in the tail of the cavity produces vortices which disappear in the rear of the projectile trajectory. Particular attention is given to the velocity attenuation of the projectile after water entry. The results show that there is a transition point at the time corresponding to the surface seal of the cavity during the velocity attenuation after oblique water entry, and the rates of velocity attenuation are different before and after this transition point. Additionally, the chronophotography of the cavity evolution shows that the time when the surface seal of the cavity occurs decreases with the increase of the initial impact velocity of the projectile.

Experimental Study of Water Entry and Exit of a Circular Cylinder at Free Surface: An Educational Approach

2012 ◽  
Author(s):  
Afshin Goharzadeh ◽  
Arman Molki
Keyword(s):  
Experimental Study ◽  
Free Surface ◽  
Circular Cylinder ◽  
Flow Visualization ◽  
High Speed ◽  
Mechanical Engineering ◽  
Water Entry ◽  
Experimental Setup ◽  
Entry And Exit ◽  
Educational Approach

This paper outlines a proposed experimental setup for characterizing the vertical motion of a horizontal circular cylinder through a free surface. Both water entry and exit are studied. The proposed experimental setup will enhance the student’s learning of the hydrodynamic impact phenomena. The experimental study is based on the flow visualization of free surface and surrounding water during the cylinder’s motion. The fluid flow phenomenon around the submerged cylinder is investigated using high-speed digital imaging and Particle Image Velocimetry (PIV). The proposed experiment is used as part of an undergraduate mechanical engineering fluid mechanics course taught at a university, which aims to educate young male and female engineers for the local oil and gas industry and particularly for the companies involved in sponsoring the institution. The details of the flow visualization system and teaching strategy for implementing this experiment in a Mechanical Engineering curriculum is discussed.

Experimental study on laminated glass responses of high-speed trains subject to windblown sand particles loading

2021 ◽  
Vol 300 ◽  
pp. 124332
Author(s):  
Gongxun Deng ◽  
Wen Ma ◽  
Yong Peng ◽  
Shiming Wang ◽  
Song Yao ◽  
...  
Keyword(s):  
Experimental Study ◽  
High Speed ◽  
Laminated Glass ◽  
Windblown Sand ◽  
High Speed Trains ◽  
Sand Particles

Experimental Study of Turbulent Macroinstabilities in an Agitated System with Axial High-Speed Impeller and with Radial Baffles

1996 ◽  
Vol 61 (6) ◽  
pp. 856-867 ◽  
Author(s):  
Oldřich Brůha ◽  
Ivan Fořt ◽  
Pavel Smolka ◽  
Milan Jahoda
Keyword(s):  
Experimental Study ◽  
Flow Field ◽  
High Speed ◽  
Experimental Results ◽  
Turbulent Regime ◽  
Frequency Of Occurrence ◽  
Visualization Method ◽  
Entire Flow

The frequency of turbulent macroinstability occurrence was measured in liquids agitated in a cylindrical baffled vessel. As it has been proved by preceding experimental results of the authors, the stochastic quantity with frequency of occurrence of 10-1 to 100 s-1 is concerned. By suitable choosing the viscosity of liquids and frequency of impeller revolutins, the region of Reynolds mixing numbers was covered from the pure laminar up to fully developed turbulent regime. In addition to the equipment making it possible to record automatically the macroinstability occurrence, also the visualization method and videorecording were employed. It enabled us to describe in more detail the form of entire flow field in the agitated system and its behaviour in connection with the macroinstability occurrence. It follows from the experiments made that under turbulent regime of flow of agitated liquids the frequency of turbulent macroinstability occurrence is the same as the frequency of the primary circulation of agitated liquid.

scholarly journals Study and Analysis of Anti Vibratory Passive and Active Methods Applied to Complex Mechanical System

2012 ◽  
Vol 7 (2) ◽  
Author(s):  
Cédric Lopez ◽  
François Malburet ◽  
André Barraco
Keyword(s):  
Experimental Study ◽  
Comparative Analysis ◽  
Mechanical System ◽  
High Speed ◽  
Test Bench ◽  
Minimization Method ◽  
Controlled System ◽  
Proper Frequency ◽  
Different Parts ◽  
Methods Of Control

This paper studies problematic of a mechanical system composed of different coupled parts submitted to a high speed shock and proposes analysis of anti vibratory passive and active methods based on an experimental and theoretical coupled approach. After a shock, different parts of the system oscillate. If one of them is excited at a particular frequency, such as its proper frequency, important oscillations appear and can lead to the deterioration of the system by introducing important stresses. In this paper, we propose an analysis in order to understand this kind of problem and what we can do to avoid it. Firstly, we discuss problematic and we expose the studied system. In a second time, we develop two approaches of modeling that allow us to understand the phenomenon by carrying out numerical simulations. Then cross checking of model is completed via experimental study on drop test bench. Passive minimization method of vibrations based on experimental and theoretical coupled approach is exposed. Finally, a comparative analysis of different methods of control and experimental results of controlled system are presented.

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