Preface 1.General Considerations 2.Basic Processes in Atomization 3.Drop Size Distributions of Sprays 4.Atomizers 5.Flow in Atomizers 6.Atomizer Performance 7.External Spray Charcteristics 8.Drop Evaporation 9.Drop Sizing Methods Index

Atomization and Sprays

Journal of Colloid and Interface Science. Editorial.

Combined effect of influence of nano additives, combustion chamber geometry and injection timing in a DI diesel engine fuelled with ternary (diesel-biodiesel-ethanol) blends

A technique is described that measures the instantaneous three-dimensional temperature distribution in water using two-color laser-induced fluorescence (LIF). Two fluorescent dyes, Rhodamine B and Rhodamine 110, are used as temperature indicators. A laser light sheet scanned across the entire measurement volume excites the fluorescent dye, and an optical system involving a color beam splitter gives the intensity distribution of the individual fluorescent dyes on two separate monochrome CCD cameras. The ratio of these fluorescence intensities at each point of the image is calibrated against the temperature to eliminate the effect of the fluctuation of illuminating light intensity. A stable thermally stratified layer was measured by this system to evaluate the total accuracy of the measurement system. The random error of the measurement was ±1.4 K with 95% confidence. Measurements of thermal convection over a heated horizontal surface show temperature iso-surfaces having typical structures such as plumes, ridges and thermals.

Whole Field Measurement of Temperature in Water Using Two-Color Laser Induced Fluorescence

IT is not often that a reissue of the collected papers of an outstanding scientific man has been called for. Some of the papers cannot fail to have historical value because of the part which their original publication played in the development of science; but that value alone would not be sufficient to secure the demand. The work involved must be of present-day importance. Therefore its consequences must still be in process of development; and it follows that if, as in the present case, the republication follows the first publication after an interval of half a century, the main papers involved must have been of very epoch-making type. The condition of present value is a sufficient test; but the most essential condition is that of permanent value. Present value persisting after the lapse of fifty years suggests permanence, and at least points to some enduring quality—the direct impress of the distinctive personality of the man. The Scientific Papers of James Clerk Maxwell. Edited By W. D. Niven. (Photographic Reprint by arrangement with the Cambridge University Press.) Vol. 1. Pp. xxxii + 607. Vol. 2. Pp. viii + 806. (Paris: J. Hermann, 1927.) 3 livres 6.

The Scientific Papers of James Clerk Maxwell

A computational model for the evaporation of urea-water-solution droplets exposed to a hot air stream

Multi-dimensional computational fluid dynamics simulations were carried out on the intake manifold and cylinder of a four-stroke single cylinder two-wheeler engine. The complex geometry of the manifold and the engine cylinder, and the motion of the intake valve were taken into consideration. Both air flow and two-phase calculations were done to predict the trajectory of the liquid fuel and identify regions of impingement which could lead to film formation and high emissions at startup. The results show that the present geometry of the manifold is non-optimum as large recirculation zones are present. The two-phase simulations show that fuel transport is significantly affected due to the recirculation under idling conditions and significant impingement occurs. The numerical results obtained could be utilized to improve the flow in the manifold for lowering emissions.Copyright © 2005 by ASME

Multi-Dimensional, Transient Fluid Flow Simulations in the Manifold of a Four-Stroke Single-Cylinder Engine

Computational Fluid Dynamics simulations are performed to study mixture preparation in the intake manifold of a small engine with Port Fuel Injection. Data from laser-based experiments on two injectors are used as inputs to the spray sub-model. The results reveal improved in-cylinder fuel distribution when the spray is directed onto the intake valve. The Sauter Mean Diameter of the spray is observed to have an insignificant effect during open valve injection, while the targeting is found to have a large influence. The methodology developed as part of this work can be used to further optimize injection parameters in such engines.

Modelling of mixture preparation in a small engine with port fuel injection

Liquid atomization is a problem with applications in many fields. In the present study, an air-assisted impinging jet atomizer has been utilised and its spray characteristics have been studied at various conditions, using water as the liquid and nitrogen as the atomizing gas. Two configurations were studied: one having a central gas jet above two impinging liquid jets, and another having a central liquid jet targeted by two inclined gas jets. Backlit imaging and particle/droplet imaging and analysis techniques were utilised to characterise the sprays. It was observed that the configuration with a central gas jet and impinging liquid jets resulted in better atomization that the other case. It was observed that both the breakup length of the sheet and the resulting droplet sizes, reduced with an increase in the gas flow rate. The diameter of the gas jet orifice was also found to play an important role in changing the spread of the spray, the droplet sizes, and the radial distribution of droplet sizes. Overall, it is observed that by varying the gas-to-liquid ratio and nozzle orifices, it is possible to obtain a fine atomization of the spray using the air-assisted impinging jet configuration even at low injection pressures of below 0.4 MP a. Introduction Air-assisted atomization, in which kinetic energy of air is used to aid liquid breakup, has been used to atomize various kinds of liquids [ 1], [2], [3]. In most of these studies, either an annular/central liquid sheet is blasted with air jets, or gas is allowed to mix with the liquid inside the atomizer to form a spray. This method requires a large amount of gas to achieve droplet sizes of the order of 50 μm. Beck et al. [ 4] achieved a Sauter mean diameter (SMD) of 75 μm with water at a gas to liquid ratio (GLR) of the order of 1.0. On the other hand, impinging jet atomization has been used in rocket engines due to its good atomization and mixing characteristics [ 5], [6]. Impinging jet experiments with water by Shen et al. [ 7] showed that jet velocities of the order of 12.5 m/s was required to obtain an SMD in the range of 300 μm. In the present study, a liquid sheet is formed using two impinging liquid jets, and an air jet is directed on to this sheet to aid the atomization process. This combined effect of impinging jet and air assisted atomization helps in achieving smaller droplets at low liquid injection velocities. Experimental Setup and Methods The experimental setup consists of two parts, a liquid and gas supply system to the atomizer, and the optical setup to measure spray characteristics. In the supply system, high pressure nitrogen from a gas bottle is regulated to the gas reservoir tank and part of it is used to compress the liquid in the liquid reservoir. Liquid and gas flow rates are controlled using needle valves in their respective lines. The gas flow rate is measured using a thermal mass flow meter, while the liquid flow is measured using a gear flow meter. Digital pressure gages placed close to the atomizer measure the injection pressure. The spray is injected in a quiescent ambient condition. The spray is collected into a tank with a small exhaust fan at the bottom which creates sufficient suction to remove the mist without affecting the spray. The atomizer used in the present study consists of two liquid nozzles with an orifice of 0.76 mm in diameter, and a gas nozzle with an orifice diameter of 1.1 mm. The gas jet is placed over the impinging point of liquid jets at a distance of 7 mm, and making equal angles with them. The liquid jets impinge and form a liquid sheet in the plane perpendicular to that containing the axes of the injectors, and the gas supplied through the gas orifice is used to assist in the break-up of this sheet. The optical setup for spray characteristic measurements is based on the backlit direct imaging method. It uses a pulsed Nd:YAG laser along with a fluorescent diffuser as a light source to back-illuminate the spray, and a CCD camera with a resolution of 2048 X 2048 pixels to record the spray images. A pulse duration of around 10 ns is used. The schematic of the experimental setup is shown in Fig. 1. In the present study, two types of image-based measurements are performed, one to study the spray structure and the other for droplet size measurements. For the spray structure measurements, images are taken from the exit of the orifice to 80 mm downstream. Small portions of the spray are imaged using a long distance microscope for droplet size measurements. ∗Corresponding author: ammohan@mecheng.iisc.ernet.in

T.N.C. Anand

Papers

A computational model for the evaporation of urea-water-solution droplets exposed to a hot air stream

Multi-Dimensional, Transient Fluid Flow Simulations in the Manifold of a Four-Stroke Single-Cylinder Engine

Modelling of mixture preparation in a small engine with port fuel injection

Experimental spray characterisation of air-assisted impinging jets

Study of primary breakup of molten tin during powder production in free-fall configuration