Nozzle Orifice Diameter Research Articles

95/05049 Spray-tip droplet SMDs of intermittent high-pressure sprays of diesel fuel compared with coal-water slurry sprays

An experimental study investigated droplet-size characteristics near the spray tip of intermittent sprays of diesel fuel from an electronically controlled accumulator injection system. A modified laser-diffraction particle-analysing technique (Malvern 2600C system) optically synchronised the data taken with the spray penetration, so that the Sauter Mean Diameter (SMD) could be measured at low obscurations without multi-scattering bias. Measurements were made at axial locations 60, 80, 100 and 120 mm downstream of the injector orifice with 0.2 and 0.4 mm diameter orifices. Injection pressures studied were 28, 56, and 83 MPa g, and measurements took place in both pressurised (2.07 MPa g) and unpressurised chamber conditions. The spray-tip SMD increased with ambient gas density and axial measurement location, and fell inversely with injection pressure. Dependence of SMD on nozzle orifice diameter was negligible for fully developed sprays. A regression equation for the SMD (μm) was found as SMD = 1.402ΔP -0.451 ρ a 0.1588 X 0.8977 where ΔP is in MPa gauge, ρ a is the ambient gas density in kg m -3 , and x is the axial measurement location in mm. These results show characteristics consistent with previous studies where coal-water slurry was the atomised liquid. Quantitatively, under identical injection conditions the droplet SMDs of diesel sprays were always smaller than those of coal-water slurry. Parametric comparisons for the two types of injected fuels are presented.

Free expansion study of liquid nitrogen

The phenomenas involved in the free expansion of liquid/superc ritical hydrogen are of great importance in many space applications. In this study, liquid nitrogen was substituted for hydrogen due to practical reasons. An experimental setup was designed to study the free expansion process when liquid/supercritical nitrogen is injected into an evacuated chamber. The effects of nozzle size, upstream pressure, and downstream pressure were studied. During the experiment, three different nozzle sizes were tested. When the pressure inside the expansion chamber was below the triple point, the nitrogen injected into the chamber solidified in two different forms. For the smallest nozzle, the solid formation occurred inside the nozzle, whereas, for the larger nozzles, the fluid solidified after being sprayed into the expansion chamber. No solidification was observed at chamber pressures higher than the triple point pressure. It was also found that supercritical nitrogen acts like a liquid in the free expansion process. Nomenclature Cd = coefficient of discharge d = nozzle orifice diameter g = gravitational acceleration L = length m = mass flow rate mN2 = mass of liquid nitrogen P = pressure Pc = critical pressure R = gas constant of nitrogen T = temperature t = time U = internal energy V = volume of the expansion chamber p = density

Diesel-Combustion Characteristics at Spool-Acceleration-Type High-Pressure Injection.

This paper describes the injection characteristics of a high-pressure fuel injection system using spool acceleration, named KD-3, and its potential for improvement of diesel combustion. The injection characteristics were investigated at various operating positions of shuttle valve limiter and operating source pressures. Engine tests were performed using high-speed direct-injection diesel engine having a high-swirl deep-bowl combustion chamber for several nozzle orifice diameters at various injection timings, engine speeds and engine loads. From the results, it was found that the injection pressure decreases with a decrease in injection fuel quantity. It should be noted that this method is useful for reduction of smoke at high loads and of NOx and noise at middle and low loads. The results also show that a smaller nozzle orifice spoils brake specific fuel consumption, due to an increasing in driving torque of this injection system.

Irrigation System Simulator for Small Plot Chemigation Research

An irrigation simulator was developed for small plot irrigation and chemigation research. The simulator was designed as a linear move system to simulate water rates (2.5 to 25 mm) of any section of a center pivot system. Water rates are selected by a combination of nozzle orifice diameter, nozzle spacing, water pressure, and transport velocity. Metering pumps inject liquid chemical treatments into two manifolds that carry water and treatment to two 4.6-m spray boom sections located in tandem on a 10.7-m truss. The system successfully chemigated plant nutrients, herbicides (pre- and post-emergence), fungicides, insecticides, and nematicides to a wide variety of crop species. The data were invaluable for determining preliminary information for chemigation research on center pivot systems.

The behavior of metal jet in the in-rotating-water spinning method.

To understand the formation of rapidly solidified metal wire directly from the molten state by the In-Rotating-Water Spinning Method, some experiments have been done by the use of Pb-Sb alloy. In the experiments, the behavior of molten metal jet in rotating water was directly observed to reveal that the jet orbit closely relates with the cross-sectional shape, longitudinal shape and continuity of wires obtained.Under the experimental conditions adopted in this study, it has been confirmed that the apparent properties of the wire are influenced mainly by both the jet velocity and the water-drum velocity. With increasing ratio of the jet velocity to the water velocity, molten metal jet penetrates deeper into rotating water. The range showing the optimum conditions for the production of long-continued straight wire has also been determined.Furthermore, the theoretical methods to estimate the jet velocity at the nozzle outlet and the jet orbit in water have been developed. The jet velocity of molten metal can well be predicted by the use of the equivalent nozzle orifice diameter obtained from the water experiment on the characteristics of nozzle. The calculated jet orbit agrees well with the observed results.

SPRAY DRYING CHARACTERISTICS BY A CENTRIFUGAL PRESSURE NOZZLE WITH LARGE ORIFICE DIAMETER

Abstract A study was made of a centrifugal pressure nozzle with large orifice diameter (8-10 nun) for producing dry milk in capacity of 2-3 tons per hour to develop some performance data on spray distribution, drop size distribution, and capacity with changing spray drying conditions such as nozzle pressure, orifice diameter and spray angle. Experimental results were shown as follows. (1) A centrifugal pressure nozzle of large capacity such as 5,000- 5,500 l/hr at 150 kg/cm2 spray pressure and 110°s ray angle was designed by using the nozzle parameter Si/dedi√di/di. (2) Atomization characteristics were greatly affected by the ratio of orifice diameter (de) to the length (L) of the nozzle core. The smaller the ratio, around 0.125, the better are the atomizing effects. (3) The large orifice can be used at least 3,000 hr in the spray drying operation for milk without any wear in the orifice although it is only made of stainless steel. As a result, a spray dryer of large capacity for dry milk has been operate...

Low Pressure Air Jet Seed Selection for Planters

ABSTRACT THE ability of low pressure air nozzles to remove (select) seeds from the seed cells of a pressurized drum planter was determined for ranges of seed density, seed drum angular velocity, and nozzle orifice diameter and supply pressure. An 8-mm diameter nozzle orifice provided the best selection. When used with nozzle supply pressures greater than 9.7 kPa, this orifice size selected plastic spheres with equal or greater accuracy than conventional seed release wheels. The data gathered were used to predict the performance improvement of a planter using such a nozzle and feedback to provide replacement seeds for skips occurring before seed release wheel selection.

Mechanism of alumina buildup in tundish nozzles during continuous casting of aluminum-killed steels

During continuous casting of aluminum-killed steels, the pouring rate through the tundish nozzle often diminishes, posing serious operating problems. This happens because a buildup of microscopic alumina particles at the nozzle orifice effectively decreases the nozzle orifice diameter and causes constriction of the liquid-steel pouring stream. There are two major aspects of the constriction problem: (1) the source of the depositing particles, and (2) the mechanism by which the particles deposit at the nozzle orifice. Detailed microscopic examination of the buildup of alumina particles in nozzles from various casting trials and petrographic examination of the nozzle refractory indicated that the particles depositing at the nozzle orifice were already present in the melt because of deoxidation and reoxidation processes. A model proposed herein explains why and how the alumina particles deposit and stay at the nozzle orifice. The model considers a microscopically thin boundary layer at the nozzle bore where the velocity of the liquid steel approaches zero. Particles passing close to the refractory surface and in the slow-moving boundary layer attach to the wall and to each other. The presence of eddy currents in and close to the turbulent boundary layer increase the particle to particle collision. Such collisions of the particles thrown from outer region of boundary layers with the already attached particles keep on dumping the particles toward the refractory surface. The high interfacial energy of alumina inclusions in steel is a driving force for particles to attach to the refractory wall and to each other, and high-temperature sintering then occurs to form a network of alumina particles.

Injection Molding with Natural Rubber

Abstract Injection moldings with natural rubber compounds having sections varying between 0.16 and 10 cm thick have been prepared. Almost any natural rubber compound can be satisfactorily injection molded. Cure time, and hence cycle time, is highly dependent on injection temperature and the art of injection molding is to inject at the highest possible temperature consistent with freedom from scorch. The injection temperature of natural rubber depends on the injection molding machine variables such as screw speed, screw back pressure and barrel temperature. Injection and mold filling time are dependent on injection pressure and nozzle orifice diameter. Rubber compounding variables influence injection molding behavior. A curing system with a relatively long, safe Mooney scorch time permits a reduction in the cure time of rubber by allowing a high injection temperature. Conventional curing systems are suitable for a wide range of injection moldings but “Efficient Vulcanization ” systems have special advantages in curing thin sections adjacent to thick ones because of their superior reversion resistance. The effects of compound viscosity are described. Extenders are shown to reduce injection temperatures and thus increase cure times. Black and white fillers are examined in their effect on injection temperature, injection time and cure time. Injection molded vulcanizates are similar in mechanical properties and oven aging resistance to vulcanizates prepared by conventional press methods.

Studies on the Penetration of Fuel Spray of Diesel Engine

Regarding the penetrating distance of fuel spray of Diesel engine, the old theory dealing with the motion of a fuel droplet in still air is recognized not to coincide with the actual phenomenon because of extremely small size of atomized fuel droplets and very high density of gas in cylinder. In this paper, the characteristics of spray penetration are discussed from the viewpoint of momentum theory based on the idea that air induced into fuel jet stream makes a kind of mixed gas together with fuel droplets. As the results of a series of experiments, the following conclusions have been reached : (1) Theory of momentum for the spray penetration holds good, and effects of elements which control the penetrating distance can be expressed by relatively simple relations consisting of non-dimensional numbers. (2) The distance of spray penetration is proportional to square roots of each of nozzle orifice diameter, injection velocity and time after injection begins, and also is influenced by density of gas in cylinder, but the effect of viscosity of gas on the penetrating distance which remained uncertain is very little. (3) Excess air coefficient of spray mixture increases in proportion to penetrating distance, and the ratio between cylinder bore and such a penetrating distance that excess air coefficient becomes one (1) gives a base of similarity of fuel spray distribution in cylinder. In the design, accordingly, nozzle orifice diameter may be determined only in proportion to cylinder bore.

噴霧散水による浮遊粉塵の抑制について

The author carried out studies, on water spray which is the most familiar for air-borne dust control, and obtained the following results on its effect.1. The larger the nozzle orifice diameter is, the more sufficient efficiency can beobtained, namely, in the diameter of each 3.0, 2.5, 2.0, and 0.8mm, it has time ratio of 1.0, 1.18, 1.45, 3.27 respectively, under the condition of 3.5kg/cm2 of water-pressure to be needed for 70% of dust suppression.2. Effect differs from the kind of rock, and, generally the sedimentary rocks have higher effect than the ignious rocks, but coals are not so high as compared with other rocks.3. The bigger the particle size of air-borne dust is, the higher effect is.4. The higher water pressure is, the higher effect is, and 8kg/cm2 of water pressure will do with water quantity of below 1/4 compared with 2.5kg/cm2.5. When wetting-reagent is used, in 1-2 min. of spray effect can be made ranking anion, cation, and nonion. But in 7-10min. of spray, the order of effect is changed to anion, nonin and cation.6. When wetting-reagent is mixed with water to be used for spray the quantity of water can be reduced by 20-30%.7. Wetting-reagent makes little difference in the effect on the kind of rock.8. Effect is lower in 'the fluidity of the air than in the still.