scholarly journals High Speed PIV Measurements in Water Hammer

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Roberto Capanna ◽  
Philippe M. Bardet
Keyword(s):  
Experimental Study ◽  
High Speed ◽  
State Of The Art ◽  
Water Hammer ◽  
Compressed Air ◽  
Piv Measurements ◽  
Laser Measurements ◽  
Relaxation Coefficient ◽  
The Impact ◽  
Metal Wall

An experimental study addressing the challenge to measure relaxation coefficient of very fast phenomena such as water hammers is presented. An acrylic projectile containing water is accelerated and impacts a metal wall creating a water hammer. State of the art laser measurements techniques will be deployed in order to achieve such goal. A compressed air custom built cannon is used to accelerate the projectile and create the impact leading to the water hammer. First experimental results for Shadowgraphy and PIV measurements are presented and discussed with focus on the future development for the presented facility.

Interfacial Heat Transfer During Droplet Impact on a Solid Surface: Comparison of High-Resolution Laser Measurements With Finite-Element Simulations

2007 ◽  
Author(s):  
Rajneesh Bhardwaj ◽  
Jon P. Longtin ◽  
Daniel Attinger
Keyword(s):  
Heat Transfer ◽  
Fluid Dynamics ◽  
Finite Element ◽  
High Speed ◽  
Element Model ◽  
Deposition Process ◽  
Interfacial Heat Transfer Coefficient ◽  
Interfacial Heat Transfer ◽  
Laser Measurements ◽  
The Impact

The objective of this work is to understand the coupling of fluid dynamics and heat transfer during the impact of a millimeter-size water droplet on a flat, solid glass substrate. In this work, a finite-element model is presented which simulates the transient fluid dynamics and heat transfer during the droplet deposition process, considering Laplace forces on the liquid-gas boundary, and the dynamics of wetting. A novel, experimental laser-based method is used to measure temperatures at the solid-liquid interface. This method is based on a thermoreflectance technique and provides unprecedented temporal and spatial resolutions of 1 microsecond and 20 micrometer, respectively. Matching between simulations, temperature measurements and high-speed visualization allows the determination of the interfacial heat transfer coefficient.

Experimental Study on the Response Characteristics of Oilcans under High-Velocity Fragment Impact

2012 ◽  
Vol 510 ◽  
pp. 500-506
Author(s):  
Chang Hai Chen ◽  
Xi Zhu ◽  
Hai Liang Hou ◽  
Li Jun Zhang ◽  
Ting Tang
Keyword(s):  
Experimental Study ◽  
High Velocity ◽  
High Speed ◽  
Room Temperature ◽  
Experimental Results ◽  
Fuel Oil ◽  
High Speed Camera ◽  
Response Characteristics ◽  
Fuel Oils ◽  
The Impact

To explore the deflagration possibility of the warship cabin filled with fuel oil under impact of high-speed fragments in the condition of room temperature, experiments were carried out employing the small aluminium oilcans filled with fuel oil. Response processes of the oilcans were observed with the help of a high-speed camera. The disintegration as well as flying scattering of the oilcans were analyzed. The reasons for atomization of the fuel oils were presented. Finally, the deflagration possibility of warship oil cabin was analyzed. Results show that the pressure inside the oilcan is quite great under the impact of the high-speed fragment, which makes the oilcan disintegration and flying scattering. Simultaneously, fuel oils inside the oilcans are atomized quickly followed by ejected in front and back directions. Under the same condition as in present tests, deflagration will not occur for fuel oils used by warships. Experimental results will provide valuable references for the deflagration analysis of warship fuel oil cabins subjected to the impact of high-velocity fragments.

Experimental Study on Mechanical Properties of Polyethylene HDPE in Conditions of Hydraulic Impact Simulation

2015 ◽  
Vol 240 ◽  
pp. 149-154 ◽  
Author(s):  
Szymon Imiełowski ◽  
Apoloniusz Kodura ◽  
Aniela Glinicka ◽  
Cezary Ajdukiewicz
Keyword(s):  
Mechanical Properties ◽  
Young’S Modulus ◽  
High Speed ◽  
Young's Modulus ◽  
Water Hammer ◽  
Pipe Material ◽  
Wear Process ◽  
Impact Simulation ◽  
Hydraulic Impact ◽  
The Impact

Experimental research on mechanical properties of hardened polyethylene HDPE, is developed in the paper. The conditions of hydraulic impact simulation, caused by sudden opening or closing of the valve or by working pomp were adopted in the model. The created in such conditions shock wave moves at a high speed causing additional dangerous dynamic loadings, which lead to faster pipe wear process. The aim of this study is to determine Young's modulus of the pipe material in the cyclic load conditions. The assumed amplitude and frequency of the applied load relates to variation of the impact wave pressure also the speed of the disturbances propagation are taken from experimental measurement of the real water hammer. The measured Young's modulus is higher than that obtained from a static tensile test. The presented study arises from the need to verify the actual value of pipe material mechanical properties, i.e. longitudinal stiffness, for designing of hydraulic pipes under conditions of water hammer.

scholarly journals Behavioral Effects of Mortality Salience: An Experimental Study

2018 ◽  
Vol 8 (4) ◽  
pp. 65
Author(s):  
Leila E. Zein ◽  
Hussein Akil ◽  
Said Hussein
Keyword(s):  
Experimental Study ◽  
State Of The Art ◽  
Terror Management Theory ◽  
Mortality Salience ◽  
Terror Management ◽  
Behavioral Effects ◽  
Management Theory ◽  
Consumer Behaviors ◽  
Consumption Choices ◽  
The Impact

The study is intended to explain the effect of Mortality Salience (MS) on consumer behaviors. In a first part, we present a state of the art of Terror Management Theory (TMT) and its contributions in management sciences by focusing on the impact of MS on consumption. In a second part, we illustrate the results of an experiment testing the effect of death reminders on consumption choices. The results of the experiment show that the reminders of death generate, for the most part of participants, pro-materialistic consumption choices. Based on these results, we highlight the effect the death reminders can generate on Lebanese consumers.

Development of High-Speed Industrial Turbo Blowers With Foil Air Bearings

2003 ◽  
Author(s):  
JongSik Oh ◽  
HeonSeok Lee
Keyword(s):  
High Speed ◽  
State Of The Art ◽  
Aerodynamic Performance ◽  
Compressed Air ◽  
Target Market ◽  
Test Results ◽  
Air Bearings ◽  
Production Lines ◽  
High Efficient ◽  
The World

In the paper, the development of high-speed industrial turbo blowers with foil air bearings is presented as a first successful commercialization in the world. Their target market is various from wastewater treatment to cement factory processes which require compressed air ranging between 0.6 and 0.8 bar gauge. Employing the state-of-the-art technology of the high-speed BLDC motors, the bump-type foil air bearings and the high-efficient turbo impellers/diffusers, so much compact, efficient and silent blower machines of a single stage are now available in the market, aiming to replace the existing inefficient, bulky and noisy ones, such as roots blowers. The first production lines are established for 75 and 150 hp class blowers. Rotational speeds up to 40,000 rpm are realized directly from the high-speed BLDC motors without any gear boxes, and no lubrication oil is required. A brief introduction of design, manufacture and test results is presented for mechanical, electrical and aerodynamic performance.

The Effect of Mach Number on the Loss Generation of LP Turbines

2012 ◽  
Author(s):  
Raúl Vázquez ◽  
Diego Torre
Keyword(s):  
Mach Number ◽  
Total Pressure ◽  
High Speed ◽  
State Of The Art ◽  
Pressure Coefficient ◽  
Airfoil Surface ◽  
High Lift ◽  
Pressure Losses ◽  
Coefficient Distribution ◽  
The Impact

The effect of Mach number on the loss generation of Low Pressure (LP) Turbines has been investigated experimentally in a pair of turbine high-speed rigs. Both rigs consist of a rotor-stator configuration. All the airfoils are high lift, high aspect ratio and high turning blades that are characteristic of state of the art LP Turbines. Both rigs are identical with exception of the stator. Two sets of stators have been manufactured and tested. The aerodynamic shape of both stators have been designed in order to achieve the same spanwise distribution of Cp (Compressible Pressure coefficient) over the airfoil surface, each one to its corresponding design Mach number (0.61 and 0.88 respectively). The aim of this experiment is to obtain the sensitivity of profile and endwall losses to Mach number by means of a back-to-back comparison between both sets of airfoils. Because the two sets of stators maintain the same pressure coefficient distribution, Reynolds number and velocity triangles, each one to its corresponding design Mach number; one can state that the results are only affected by the compressibility. Experimental results are presented and compared in terms of area average, radial pitchwise average distributions and exit plane contours of total pressure losses. To complete the paper, the impact of the results on the design of LP Turbines is discussed and presented.

scholarly journals Wrapping up a century of splashes

2016 ◽  
Vol 800 ◽  
pp. 1-4 ◽  
Author(s):  
Devaraj van der Meer
Keyword(s):  
High Speed ◽  
Vacuum Chamber ◽  
State Of The Art ◽  
Classical Problem ◽  
Liquid Pool ◽  
Scientific World ◽  
The Impact ◽  
Shed Light

Few fluid phenomena are as beautiful, fragile and ephemeral as the crown splash that is created by the impact of an object on a liquid. The crown-shaped phenomenon and the physics behind it have mesmerised and intrigued scientists for over a century, and still the scientific world has not yet uncovered all of the secrets of the splash. This is exemplified in a particularly striking manner in Marston et al. (J. Fluid Mech., vol. 794, 2016, pp. 506–529) where a 6 m tall vacuum chamber is employed to study the splash formed upon impact of a sphere onto a deep liquid pool, at both atmospheric and reduced ambient pressures. They shed light into the classical problem of the surface seal and study the buckling of the splash. With an almost magical touch they devise a method to create a splash without the liquid and the sphere ever coming into contact. The images that accompany the paper – taken with state-of-the-art high-speed cameras – are as stunning as the physics that is uncovered in them.

scholarly journals Compressible air entrapment in high-speed drop impacts on solid surfaces

2013 ◽  
Vol 716 ◽  
Author(s):  
Yuan Liu ◽  
Peng Tan ◽  
Lei Xu
Keyword(s):  
High Speed ◽  
Solid Substrate ◽  
Compressed Air ◽  
Viscous Drag ◽  
High Speed Photography ◽  
Air Entrapment ◽  
Large Pressure ◽  
Drop Impacts ◽  
Air Film ◽  
The Impact

AbstractUsing high-speed photography coupled with optical interference, we experimentally study the air entrapment during a liquid drop impacting a solid substrate. We observe the formation of a compressed air film before the liquid touches the substrate, with internal pressure considerably higher than the atmospheric value. The degree of compression highly depends on the impact velocity, as explained by balancing the liquid deceleration with the large pressure of the compressed air. After contact, the air film expands vertically at the edge, reducing its pressure within a few tens of microseconds and producing a thick rim on the perimeter. This thick-rimmed air film subsequently contracts into an air bubble, governed by the complex interaction between surface tension, inertia and viscous drag. Such a process is universally observed for impacts above a few centimetres high.

scholarly journals Problems of an experimental study of a reverse flow in the turbulent channel flow

2021 ◽  
Vol 2057 (1) ◽  
pp. 012097
Author(s):  
D I Zaripov
Keyword(s):  
Experimental Study ◽  
Measurement Error ◽  
Channel Flow ◽  
Spatial Resolution ◽  
High Speed ◽  
High Spatial Resolution ◽  
Reverse Flow ◽  
Turbulent Channel Flow ◽  
Measurement Methods ◽  
Piv Measurements

Abstract The problems of experimental study of the near-wall reverse flow (NWRF) phenomenon observed in a turbulent channel flow are discussed. Until now, the problem of detecting the NWRF events has been associated with the lack of spatial resolution of measurement methods. The present study, using the example of high-speed PIV measurements, shows that problems associated with the influence of the measurement error arise even when a high spatial resolution is achieved.

Sign in / Sign up

Export Citation Format

Share Document