Effect Of Orifice Size Research Articles

Experimental investigation of jet impingement during accidental release of liquid CO2

Jet impingement and low-temperature damage are potential risks of accidental release during the transportation and storage of liquid CO2. An experimental system was built to investigate the characteristics of jet impingement of liquid CO2. The effects of orifice size and impinging distance on the impinging force of the jet and temperature of the target surface were investigated at 2.3 MPa and 5 MPa, with orifice sizes from 2 to 4.84 mm and impinging distances from 0.25 to 1.5 m. A jet impingement model was established considering the initial pressure, orifice size, impinging distance and impingement area. The experimental results indicated that dry-ice attached on the plate surface, reducing the surface temperature to −90 °C and improving the impinging force to 44.54 N with decreasing impingement distance. The variation in initial pressure had a more pronounced effect on the impinging force than on the impinging temperature, while the impingement distance had more influence on the impinging temperature than the orifice size and initial pressure. The results calculated with the model agreed well with the experimental results with an error of nearly less than 20%. The model was also used to analyse the effects of the initial pressure, liquid mass fraction, orifice size, impingement distance and impingement area on the release rate and impingement force.

Turbulence Characteristics of Cavitating Flows Downstream of Triangular Multiorifice Plates

Cavitating flow fields downstream of triangular multiorifice plates with different geometrical parameters were measured by PIV technique, and effects of orifice size, orifice number, and orifice layout on turbulence intensity and Reynolds stress were analyzed. The experimental results showed that the turbulence intensity and Reynolds stress downstream of the different multiorifice plates exhibited sawtooth-like profiles. Decrease in orifice size, increase in orifice number, and taking staggered layout could contribute to intensification of turbulence mixing and shear effects of multiple cavitating jets downstream of the multiorifice plates and thus reaching the expected cavitation effects.

Effect of orifice size on liquid breakup dynamics and spray characteristics in slinger atomizers

The ability of the rotary slingers to achieve fuel atomization by employing the rotational speed of the turbine shaft obviates the use of high-pressure fuel pump and makes those a popular choice for small gas turbine engines. Such atomizers contain arrays of orifices on their outer periphery for injection of the liquid into the combustion chambers. In the present work, we experimentally investigate the influence of the choice of orifice size on primary liquid breakup dynamics and spray characteristics in slinger atomizers. Three slinger discs with the same disc size and number of orifices but with different orifice size, d o (= 1 mm, 1.5 mm, and 2 mm) are examined in a high-speed slinger test rig for a range of rotational speed (2000–10,000 rpm) and liquid feed rate (0.2–1 lpm). The operating conditions are relevant to part-load and engine relighting conditions for which the selection of geometric parameters of the injector may play a crucial role in achieving the atomizer performance. In the current work, the liquid breakup process in the vicinity of the slinger orifices was visualized using front light illumination technique, whereas the pulse-shadowgraph technique was employed for droplet sizing. It is found that smaller orifice size promotes column mode of liquid breakup which results in larger primary liquid breakup length and subsequently results in larger Sauter mean diameter. The results highlight that the orifice size is an important design parameter as the liquid atomization in slinger atomizers is sensitive to the selection of orifice size especially for lower range of rotational speeds.

Effects of orifice size on the efficiency of a heaving oscillating water column

ABSTRACT Oscillating water columns (OWCs) have been studied extensively as promising wave energy converters. Different factors can affect the pneumatic power of OWCs, such as model scaling, turbine damping, and air compressibility. In this study, the heave motion of the OWC was limited by adding friction, and the effect of orifice size on the pneumatic power of an OWC from an unconstrained to a fixed position was investigated using a numerical method combining the k-ε/laminar model, the VOF interface capturing method, the motion-based zonal mesh update method and the 6DOF solver. Two groups of validation experiments and a study of model scaling were carried out to verify the effectiveness of the numerical method. It is concluded that the orifice open area ratio has an optimal value of approximately 1% whether the model is stationary or heaving; however, the heave motion has a significant weakening effect on the pneumatic power. More power can be extracted by constraining the heave motion of the OWC.

Effect of orifice size on quality characteristics of burger made from spent laying duck meat

An experiment was carried out to investigate the influence of orifice size (4.5, 6, 8 and 10 mm) on the quality characteristics and acceptability of duck burger made from spent laying Khaki Campbell duck meat. Large orifice size resulted in lower fat and protein content compared to small orifice size. Hardness value also decreased significantly (p < 0.05). However, there was no significant difference (p > 0.05) in the diameter of shrinkage, cooking loss and colour of the burger. However, the hardness value decreased significantly with an increase in orifice size. The sensory evaluation showed no significant difference (p > 0.05) within the samples, but the overall acceptability score for burger prepared using 10 mm grind size was higher compared to those prepared at 4.5, 6 and 8 mm orifice sizes. Hence the 10 mm grind size was adopted as the optimum orifice size for spent laying Khaki Campbell duck burger.

Numerical Simulation of Self-Propelled Steady Jet Propulsion at Intermediate Reynolds Numbers: Effects of Orifice Size on Animal Jet Propulsion

Most marine jet-propelled animals have low swimming efficiencies and relatively small jet orifices. Motivated by this, the present computational fluid dynamics study simulates the flow for a jet-propelled axisymmetric body swimming steadily at intermediate Reynolds numbers of order 1–1000. Results show that swimming-imposed flow field, drag coefficients, swimming efficiencies, and performance index (a metric comparing swimming speeds sustained by differently sized orifices ejecting the same volume flow rate) all depend strongly on orifice size, and orifice size affects the configuration of oppositely signed body vorticity and jet vorticity, thereby affecting wake and efficiency. As orifice size decreases, efficiencies decrease considerably, while performance index increases substantially, suggesting that, for a given jet volume flow rate, a smaller orifice supports faster swimming than a larger one does, albeit at reduced efficiency. These results support the notion that most jet-propelled animals having relatively small jet orifices may be an adaptation to deal with the physical constraint of limited total volume of water available for jetting, while needing to compete for fast swimming. Finally, jet orifice size is discussed regarding the role of jet propulsion in jet-propelled animal ecology, particularly for salps that use two relatively large siphons to respectively draw in and expel water.

Killing rate of colony count by hydrodynamic cavitation due to square multi-orifice plates

Currently,in water supply engineering, the conventional technique of disinfection by chlorination is employed to kill pathogenic microorganisms in raw water. However, chlorine reacts with organic compounds in water and generates disinfection byproducts (DBPs), such as trihalomethanes (THMs), haloacetic acids (HAAs) etc. These byproducts are of carcinogenic, teratogenic and mutagenic effects, which seriously threaten human health. Hydrodynamic cavitation is a novel technique of drinking water disinfection without DBPs. Effects of orifice size, orifice number and orifice layout of multi-orifice plate, cavitation number, cavitation time and orifice velocity on killing pathogenic microorganisms by cavitation were investigated experimentally in a self-developed square multi-orifice plate-type hydrodynamic cavitation device. The experimental results showed that cavitation effects increased with decrease in orifice size and increase in orifice number, cavitation time and orifice velocity. Along with lowering in cavitation number, there was an increase in Reynolds shear stress,thus enhancing the killing rate of pathogenic microorganism in raw water. In addition, the killing rate by staggered orifice layout was greater than that by checkerboard-type orifice layout.

Large eddy simulation of a homogeneously charged turbulent jet ignition system

Transient jet ignition of a homogeneous methane air mixture in a turbulent jet ignition system is studied computationally using a large eddy simulation turbulence model. The jet discharges from a prechamber into a main combustion chamber via one or more orifice(s) and provides a distributed ignition source in turbulent jet ignition. The effect of orifice size and stoichiometry is studied numerically using the Converge computational fluid dynamics code. A reduced kinetic mechanism is used for combustion along with a Smagorinsky sub-model for turbulence modeling. The computed pressure traces are compared with experimental measurements through rapid compression machine tests. Computational fluid dynamics results are in acceptable agreement with the experimental data during compression and the early stage of combustion; however, an over-prediction of peak pressure was reported. Peak pressure error is in the range of 0.1%–4% for Reynolds-averaged Navier–Stokes simulation estimation compared to the experimental measurements. This error is a function of mixture stoichiometry and unburned gas temperature. The error calculation showed that with the large eddy simulation model, 1% and 12% improvements in peak pressure and burn rate estimations, respectively, were achieved compared to Reynolds-averaged Navier–Stokes results. The reduced large eddy simulation error relative to the Reynolds-averaged Navier–Stokes simulations were considered to be in the acceptable range; however, further improvements could be achieved through validation and testing of additional turbulence models. In addition, computational fluid dynamics temperature contours for various nozzle orifices and air–fuel ratios are compared to achieve deeper insight into the turbulent jet ignition combustion process in the rapid compression machine combustion cylinder. The numerical iso-surface temperature contours were obtained which enabled three-dimensional views of the flame propagation, the jet discharge, ignition and extinction events. The heat release process and regeneration of mid-range temperature iso-surfaces (1200 K) were not visible through the experimental images.

STUDY THE ORIFICE EFFECTS OF A SYNTHETIC JET ACTUATOR DESIGN

The synthetic jet actuator is an active flow control device that is used to improve the aerodynamic performance on working surfaces such as wings, helicopter blades and ground vehicles. The performance of synthetic jet actuator depends on the design of the orifice and cavity, and the oscillating driver. Piezoelectric diaphragm was used as an oscillating driver because of its small size and easier installation. The focus of this project is to study the effects of orifice size and shape for a synthetic jet actuator design. The effects were studied on circular and rectangular shapes, and different sizes of orifice. Meanwhile, the configurations of the cavity are fixed. Experiments were performed to determine the maximum pulse jet velocity and turbulence intensities of the jet coming out of the orifice, driven by the Piezoelectric diaphragm at different frequencies, at constant input voltage of 2V. The experiment mainly involved the measurement of the exit pulse jet velocity using a hot-wire anemometer. The results demonstrated that the circular orifice produced higher maximum pulse jet velocity and smaller sizes orifices, both circular and rectangular, results in higher velocity jets.

Mass transfer in a spray column during two-phase extraction of horseradish peroxidase

Multistage contactors are often needed to achieve the desired degree of mass transfer. One such contactor is spray column, which can be conveniently used to isolate and purify proteins using aqueous two-phase extraction. The effects of orifice size and addition of NaCl on the overall mass transfer coefficient ( K L a) of horseradish peroxidase (HRP) and fractional dispersed phase hold up ( ε D) have been studied in a simple spray column using a polyethylene glycol/potassium phosphate aqueous two-phase system. K L a and ε D increased with an increase in dispersed phase superficial velocity ( v s) as well as capillary diameter. The presence of NaCl increased K L a. The overall mass transfer coefficient for HRP normalized for dispersed phase hold up, was found to be independent of v s in the range studied.

Prediction of Pressure Drop in an Orifice Scrubber Based on a Lagrangian Approach

A mathematical model has been developed to predict pressure drop in an orifice scrubber. This model is based on a Lagrangian approach for droplet movement and a particle-source-in-cell (PSI-CELL) model for calculating droplet concentration distribution. The k-ε turbulent model including body force due to the drag force between fluid and droplets was used to evaluate the fluid velocity distribution. The effect of orifice size on pressure drop and the correlations for mean droplet diameter have been studied. The results from the model have been compared with experimental data. This comparison shows excellent agreement between the calculated results and the experimental data.

Effects of Orifice Size and Impinging Angle on the Characteristics of a Like-Doublet Impinging-Jet

Effects of Orifice Size and Impinging Angle on the Characteristics of a Like-Doublet Impinging-Jet

Atenolol Gastrointestinal Therapeutic System. I. Screening of Formulation Variables

Conventional dosage forms are disadvantageous for drugs having short half-lives because of cyclic under- or overdosing and problems of patient compliance. The matrix or reservoir type of controlled-release dosage form provides an alternative. However, bioavailability fluctuations due to gastric pH variations continue to be a problem for many drug candidates. Osmotically controlled drug delivery systems provide a means of eliminating the effect of pH on drug release. However, the literature information is very limited for the effects of formulation variables and other process variables on the release kinetics of drugs from osmotically controlled systems. The objective of this study was to evaluate the factors that influence the release of atenolol, a cardioselective p blocker, from biconvex. bilayered, osmotically controlled tablets coated with a semipermeable membrane of cellulose acetate. Coating was achieved using a Uni-Glatt fluidized-bed coater. Orifices were drilled for drug release and a seven-factor 12-run Plackett-Burman screening technique was employed to evaluate the effects of orifice size, coating level, amounts of sodium chloride, Polyox® N80 and 303, and Carbopol® 934P and 974P on drug release. Response variable was cumulative percent released in 24 hr with constraints on time for 25% and 50% drug release. Factors showing maximum influence on drug release in decreasing order were amounts of Carbopol 934P, coating levels, and orifice size, with the main effect magnitudes of -43.1, 11.56, and 8.17, respectively. Comparative studies for the drug-additive interactions were peeormed using x-ray diffraction and differential scanning calorimetry (DSC). Results of Plackett-Burman screening, x-ray diffraction, and DSC studies are presented.

Investigation into the effects of orifice size, offset and overclamp ratio on the lubrication of slipper bearings

This paper represents the results of an experimental investigation of the performance of hydrostatic slipper bearings in axial piston pumps and motors. The effect of clamping ratio, offset loading and orifice size on the behaviour of overclamped and underclamped slippers is outlined. It is shown that the slippers run satisfactorily with no orifice and have their greatest resistance to tilting couples and to minimum film thickness. The underclamped slippers and slippers with larger orifice diameter run with relatively larger clearance and tilt than those of overclamped slippers with no orifice. Cavitation tends to affect the slippers, especially at the rear of the slipper. Ineffective flood lubrication may be the cause and oil jet pressure must be maintained to prevent oil starvation.

Effects of Orifice Size on Microsprinkler Clogging Rates

The clogging rates of microsprinkler emitters with orifice diameters of 0.76 mm (0.03 in., black base), 1.02 mm (0.04 in., blue base), 1.27 mm (0.05 in., green base), and 1.52 mm (0.06 in., red base) were evaluated in a citrus grove over a three-year period. The experiment used a randomized complete block design with eight emitters per plot and five replications of each treatment. The irrigation water was drawn from a pond, treated with one of two water conditioners, and filtered through a sand media filter. Every three months, each emitter was inspected and those that were clogged were examined to determine the cause of clogging. All fouled emitters were thoroughly cleaned and/or replaced. Overall, 46% of the clogging was due to algae, 34% was from ants and spiders, 16% was from snails, and 4% was from physical particles such as sand and bits of PVC. About 20% of the black base emitters required cleaning or replacement during each quarter compared to about 14% of the blue base, 7% of the green base, and 5% of the red base emitters. The total clogging rate was found to be inversely related to the orifice area of the emitters during the three-year study.

Effects of orifice size and shape on flow rate estimated from flow convergence region imaged by color Doppler flow mapping proximal to restrictive orifices: An in vitro study

Effects of orifice size and shape on flow rate estimated from flow convergence region imaged by color Doppler flow mapping proximal to restrictive orifices: An in vitro study