Visualization of Angular Particle-Bubble Surface Interaction using a High Speed Video Camera

Flotation is an important process in mining industries. This process employs the bubble and hydrophobic properties of a particle to separate valuable mining particles from impurities. The most important phenomenon in determining flotation efficiency is the bubble-particle interaction; therefore, understanding this phenomenon is very important. The aim of this research is to study the mechanism of bubble-particle interactions with and without the addition of a collector. The experimental setup consists of a water container, bubble generator, particle feeding system, and an image capturing system. The water container is made from transparent material of a size large enough so that the wall’s effects on bubbles and particles can be neglected. Air bubbles are generated by a bubble generator which consists of a small nozzle and programmable syringe pump. A high speed video camera and halogen lamp backlighting system are used as image capturing devices. Observation of the images reveals that bubble-particle interaction follows the stages of bubble-particle collision, particle attached to the bubble, and particle detached from the bubble. The addition of a collector to the liquid affects the bubble-particle interactions

The effect of plasma actuator utilization to the reduction of aerodynamic drag of cylinder and box models

Aerodynamics drag reduction has an advantage in terms of conversion and conservation energy. Many technologies have been developed in order to reduce the aerodynamics drag, one of them is plasma actuator. Plasma actuator as an alternative kind of active flow control is very promising and powerful in modifying the flow comprehensively. By using ion particles, plasma actuator becomes the forefront in terms of modify a flow and becomes a reliable solution in order to overcome the problems which arise in other types of active control such as installation problems, excessive moving parts which are difficult to control and others. Plasma actuator consists of two sheets of copper electrodes separated by a dielectric material made of acrylic. The final output of the plasma actuators is the ion wind which generated from the movement phenomenon of the air flow around the actuator and was the result of the ionization process in the air so that the air molecules was induced and became unstable. This paper presented two test models, a cylinder which the actuator was placed at the point of separation and a box with two plasma actuators placed at the leading edge and trailing edge to test the ability of plasma to reduce aerodynamic drag effect. The experimental results showed that the plasma actuator with a cylinder model with the 90 degree position can produce aerodynamic drag reduction by 20% while for a box model with a flow rate of 2 [m/s] generated 14.16% reduction of aerodynamic drag.papers presented to the 12th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Costa de Sol, Spain on 11-13 July 2016

Modification of Flow Structure Over a Van Model by Suction Flow Control to Reduce Aerodynamics Drag

Automobile aerodynamic studies are typically undertaken to improve safety and increase fuel efficiency as well as to  find new innovation in automobile technology to deal with the problem of energy crisis and global warming. Some car companies have the objective to develop control solutions that enable to reduce the aerodynamic drag of vehicle and  significant modification progress is still possible by reducing the mass, rolling friction or aerodynamic drag. Some flow  control method provides the possibility to modify the flow separation to reduce the development of the swirling structures around the vehicle. In this study, a family van is modeled with a modified form of Ahmed\u27s body by changing the orientation of the flow from its original form (modified/reversed Ahmed body). This model is equipped with a suction on the rear side to comprehensively examine the pressure field modifications that occur. The investigation combines computational and experimental work. Computational approach used  a commercial software with standard k-epsilon flow turbulence model, and the objectives was  to determine the characteristics of the flow field and aerodynamic drag reduction that occurred in the test model. Experimental approach used load cell in order to validate the aerodynamic drag reduction obtained by computational approach. The results show that the application of a suction in the rear part of the van model give the effect of reducing the wake and the vortex formation. Futhermore, aerodynamic drag reduction close to 13.86% for the computational approach and 16.32% for the experimental have been obtained

The Effect of Orifice Shape on Convective Heat Transfer of an Impinging Synthetic Jet

A greater heat load due to the miniaturization of electronic products causes the need for a new cooling system that works more efficiently and has a high thermal capacity. A synthetic jet is potentially useful for the cooling of electronic components. This paper reports the results of our experimental studies and the influence of orifice shape for Impinging Synthetic Jet cooling perfomance. The effect of shape of the orifice of an impinging synthetic jet assembly on the apparatus cooling of a heated surface is experimentally investigated. It will be seen that the characteristics of convective heat transfer will occur by moving the piezoelectric membrane. The prototype of the synthetic jet actuator is coupled with two piezoelectric membranes that operate by 5 volt electrical current and create a sinusoidal wave. The orifice shapes considered are square and circular. The results show the significant influence of orifice shape and sinusoidal wave frequencies on the heat transfer rate that were obtained. The temperature drop with a square orifice is found to be larger than that with circular shapes. A square orifice has a larger covered area if compared to the circular orifice at the same radius, thus resulting in a larger entrainment rate that leads to an increase of heat transfer performance

Characteristics of Vortex Ring Formation by Synthetic Jet Actuators in Different Cavities

This paper presents a baseline study of the development of turbulent flow separation for controlling aerodynamic phenomena, especially in the design of the vehicle body. The purpose of this study was to analyze the performance of synthetic jet actuators (SJAs) as one of the tools that can be used in reducing the flow controller separation area on the bluff body model of the vehicle. To get maximum results in the performance of the SJA, this research starts with characterizing the actuator, including changes in the shape of the cavity and orifice diameter. Cavity shapes tested were half-ball (B), tube (T) and cone (K), while orifice diameters of 3, 5 and 8 mm were examined. The study was conducted using both computational and experimental approaches. Results from both types of research methods were compared and displayed in graphical form. These results serve as a reference for determining future research. The experimental results, in the form of the flow rate for each type of cavity, determined the ability of different cavity conditions to form vortex rings, whereas in CFD simulations, the formation of vortex rings was demonstrated via the visualization of flow contours. Vortex rings occurred in cavity conditions B3, T3, T5, K3 and K5. Vortex rings were not formed on any type of cavity with an orifice having a diameter of 8 mm

Drag reduction by combination of flow control using inlet disturbance body and plasma actuator on cylinder model

Flow past a cylinder is one of the things that is very applicable in everyday life. But behind those facts, there is a problem in it namely the drag force which is adverse and needs to be reduced. This research was conducted to find solutions to reduce drag by using a mix of passive flow control of inlet disturbance body and active flow control from plasma actuators. This research uses a test model in the form of a cylinder of a diameter of 120 mm with Reynolds Number 15000, 41000, 62000 and was expected to reduce drag after a given combination of flow control. From the results shown, either inlet disturbance of body and plasma actuators as well as a combination of both the flow of control is capable of performing the reduction coefficient of drag up to 70,22% on a variation of the Reynolds Number 62000

MODIFICATION OF FLOW STRUCTURE OVER A VAN MODEL BY SUCTION FLOW CONTROL TO REDUCE AERODYNAMICS DRAG

Automobile aerodynamic studies are typically undertaken to improve safety and increase fuel efficiency as well as to  find new innovation in automobile technology to deal with the problem of energy crisis and global warming. Some car companies have the objective to develop control solutions that enable to reduce the aerodynamic drag of vehicle and  significant modification progress is still possible by reducing the mass, rolling friction or aerodynamic drag. Some flow  control method provides the possibility to modify the flow separation to reduce the development of the swirling structures around the vehicle. In this study, a family van is modeled with a modified form of Ahmed's body by changing the orientation of the flow from its original form (modified/reversed Ahmed body). This model is equipped with a suction on the rear side to comprehensively examine the pressure field modifications that occur. The investigation combines computational and experimental work. Computational approach used  a commercial software with standard k-epsilon flow turbulence model, and the objectives was  to determine the characteristics of the flow field and aerodynamic drag reduction that occurred in the test model. Experimental approach used load cell in order to validate the aerodynamic drag reduction obtained by computational approach. The results show that the application of a suction in the rear part of the van model give the effect of reducing the wake and the vortex formation. Futhermore, aerodynamic drag reduction close to 13.86% for the computational approach and 16.32% for the experimental have been obtained.Keywords: active flow control, aerodynamic drag reduction, reversed Ahmed body, suctio

Sistem Fluida 'Prinsip Dasar dan Penerapan Mesin fluida,Sistem Hidrolik dan Sistem Pneumatik'

xiv, 274 hlm .;25 c

Statistik untuk sains dan teknik

vi, 230 halaman : 24 c

Sistem fluida : prinsip dasar dan penerapan mesin fluida, sistem hidrolik, dan sistem pneumatik/ Harinaldi

274 hal.: ill.; 23 cm