Sharif Digital Repository

In this work, the cone-jet mode of electrospray is simulated by a two phase solver in OpenFoam software. For this aim firstly, breakup of a liquid jet is examined without applying any electric potential to the injecting capillary and results are compared with other works to evaluate the two phase solver. Next with applying electric potential, the whole evolution of cone-jet in time is simulated. One of the most important issues in this mode is the minimum potential that needs to form a stable cone-jet in different flow rates. These minimum voltages are obtained in various flow rates and compared with other experimental and computational works. Result shows that with increasing flow rate the... 

In the present study liquid thermophysical properties in electrospray has been studied. Other parameters such as electrical configuration do not change during this study. For this purpose Alcoholic fuels have been chosen because of their high energy density and their polarity that make them suitable for electrospraying. Electrical conductivity, surface tension, viscosity, density and permittivity are the most effective liquid properties in the electrospraying. The visualization method used for this study is shadowgraphy and light scattering method. In this study the range of flow rate and voltage is acquired for each operational mode and Q-V diagram has been obtained for all liquids... 

Liquid jet behavior in an intense electric field is studied experimentally and numerically.Imaging is used in experiments to charactrize jet behavior. Electrospray of ethanol using a simple needle in a wide range of operating conditions is investigated. Liquid meniscus is captured using a high-speed camera and different electrospray modes are described based on involved forces. A new nozzle is invented that broadens the stability margins of the useful cone-jet mode. The physical mechanisms of the new cone-jet is discussed and it is characterized using appropriate dimensionless parameters. A simple jet in presence of a gaseous crossflow and a normal electric field is also studied. The liquid... 

Electrospray is an interesting method to produce spray. This study has an insight on electrospraying phenomenon and its effective parameters. All modes, the forces and the situation to establish has been investigated for ethanol. Suitable configuration is introduced and for different flow rates and voltages the phenomenon is studied. Images are captured by two camera (high speed camera and high resolution camera) by using two method (shadowgraphy and light scattering). In the respect of producing fine and monodisperse droplets in cone-jet mode the stability of this mode is imported to enlarge. The special nozzle is design to increase stability of cone-jet mode even 70 times of using... 

The purpose of this project is investigating the effect of cross flow and electric field on a liquid simple-jet experimentally. In this research the effect of parameters such as liquid to air momentum ratio, electric field on jet trajectory, penetration and the lenght of breakup point with respect to the jet outlet were studied. The air was produced by a blower in a duct with square test section of 8 cm sides. The air velocity varied from 1 m/s to 11 m/s. Liquid ethanol was injected into the duct with a needle with outer diameter of 0/62 mm and inner diameter of 0.4 mm and 28 mm length. The velocity of jet was 0/62 m/s while the change of liquid to air momentum ratio was from 3 to 260 The... 

The electrospray technique involves the production of small charged droplets through the application of electrohydrodynamic forces. Under well-defined operating conditions, multiple flow modes can be observed, among which the stable jet-cone mode has received significant attention from the research community. This mode is desirable due to its uniform droplet diameter, reduction in droplet rebound when impacting hot surfaces, and potential for utilizing two-phase heat transfer for cooling purposes. In this study, a comprehensive experimental investigation was conducted to evaluate the cooling of hot surfaces through the use of electrospray in the steady cone-jet mode. The fundamental... 

Electrospray is one of the liquid spraying methods. This study has an insight on Electrospray phenomenon and its effective parameters. First, there is a short introduction of phenomenon, then, how it works and effective factors related to the procedure are described. All modes, the forces and the situation to establish has been investigated for ethanol sprayed from hemispherical nozzle. Suitable configuration is introduced and for different flow rates and voltages the phenomenon is studied. One of the innovations of this study is the imaging technique used to captured high-quality images. In fact, captured images by means of high-power light-emitting diode (LED) synchronized with digital...