Orifice resistance for ejection into a grazing flow

To explain the decrease in orifice resistance with the addition of grazing flow, the flow from an orifice was modeled by using an inviscid analysis which is valid when the orifice flow total pressure is nearly the same as the free stream grazing flow total pressure. For steady outflow from an orifice into a grazing flow, the orifice flow can enter the main grazing flow in an inviscid manner without generating large eddies to dissipate the kinetic energy of the jet. From the analysis, a simple closed-form solution was developed for the steady resistance for ejection from an orifice into a grazing-flow field. The calculated resistance compare favorably with data for a flow regime where the total pressure difference between the grazing flow and the orifice flow is small

Development of the orifice plate with a cone swirler flow conditioner

Purpose - The sensitivity of orifice plate metering to poorly conditioned and swirling flows are subjects of concerns to flow meter users and manufacturers. The distortions caused by pipe fittings and pipe installations upstream of the orifice plate are major sources of this type of non-standard flows. These distortions will alter the accuracy of metering up to an unacceptable degree. Design/methodology/approach - The design of orifice plate meters that are independent of the initial flow conditions of the upstream is a major object of flow metering. Either using a long straight pipe or a flow conditioner upstream of an orifice plate usually achieves this goal. The effect of cone swirler flow conditioner for both standard and non-standard flow conditions has been carried out in the experimental rig. The measuring of mass flow rate under different conditions and different Reynolds numbers were used to establish a change in discharge coefficient relative to a standard one. Findings - The experimental results using the cone swirler flow conditioner showed that the combination of an orifice plate and cone swirler flow conditioner is broadly insensitive to upstream disturbances. The results clearly show that this flow conditioner can attenuate the effect of both swirling and asymmetric flows on metering to an acceptable level. Originality/value - Previous work on the orifice plate has shown that the concept has promise. The results of using a combination of a cone swirler and orifice plate for non-standard flow conditions including swirling flow and asymmetric flow show this package can preserve the accuracy of metering up to the level required in the standards, providing that a new discharge coefficient is used for the combined swirler and orifice plate

Comparisons of wing pressure distribution from flight tests of flush and external orifices for Mach numbers from 0.50 to 0.97

Wing pressure distributions obtained in flight with flush orifice and external tubing orifice installations for Mach numbers from 0.50 to 0.97 are compared. The procedure used to install the external tubing orifice is discussed. The results indicate that external tubing orifice installations can give useful results

Geometrical design of stand pipe air distributors for the combustion of municipal solid waste in a fluidised bed

The new geometrical design of stand-pipe air distributor for the combustion of the municipal solid waste was presented. The new design of the air distributors enables penetration of incombustible and unburnt carbon through opening between the air distributors, thus providing easy maintenance work. The fluidized bed experimental rig was constructed using Perspex column in which air was supplied through the distributors below it. In order to establish the final geometrical design of the air distributors, several design parameters were investigated. The effect of orifice size, distance between orifice and distance between distributor pipes on the fluidization behaviour were studied. Investigation on the effects of various orifice sizes of 1.5 mm, 2 mm, 3 mm, 4 mm and 5 mm showed that the 3 mm orifice size exhibited the most stable fluidization behaviour. Investigation on some selected orifice distances of 10 mm, 20 mm, 30 mm and 40 mm also found that the 10 mm orifice distance exhibited stable growths of bubbles. Various pipe distances of 30 mm, 40 mm, 50 mm, 60 mm and 70 mm were also investigated and the most suitable pipe distance was 70 mm

Multi-element spherical shell generation

A nozzle assembly in a multi-element spherical shell generation system includes first and second side-by-side spaced apart nozzles and a web portion extending between and connecting the nozzles. The first nozzle has an inner orifice adapted to discharge a first filler material and an outer annular orifice separated from and defined in concentric relation about the inner orifice and adapted to discharge a first shell material. The second nozzle has an inner orifice adapted to discharge a second filler material and an outer annular orifice separated from and defined in concentric relation about the inner orifice and adapted to discharge a second shell material. A multi-element spherical shell can be formed through employment of the nozzle assembly by merger with one another after discharge from the outer orifices of the nozzles of a pair of adjacent annular streams of liquid or molten shell wall material of different compositions and encapsulation by the mixed shell wall materials of a common encapsulated core fluids also simultaneously discharged by the inner orifices nozzles. On the other hand, the pair of encapsulating streams of shell wall material can be of the same materials which merge together and encapsulate core fluids of different compositions which will merge together after discharge from the nozzles

Influence of liquid surface tension (surfactants) on bubble formation at rigid and flexible orifices

The influence of liquid surface tension on the bubble formation from both rigid and flexible orifice has been investigated. The liquid phases under test are aqueous solutions with butanol or surfactants (cationic, non-ionic and anionic); static and dynamic measurements of liquid surface tension have been performed to characterise them. This study shows that the effect of surface tension on the bubbles generated cannot be analysed only in terms of the static surface tension, but also depends on whether the bubbles are generated from a rigid orifice or from a flexible orifice. The kinetics of adsorption and diffusion of the solute molecules towards the bubble interface have to be taken into account insofar as their time scales are comparable to those of the bubble formation phenomenon

Experiments and modeling of dilution jet flow fields

Experimental and analytical results of the mixing of single, double, and opposed rows of jets with an isothermal or variable-temperature main stream in a straight duct are presented. This study was performed to investigate flow and geometric variations typical of the complex, three-dimensional flow field in the dilution zone of gas-turbine-engine combustion chambers. The principal results, shown experimentally and analytically, were the following: (1) variations in orifice size and spacing can have a significant effect on the temperature profiles; (2) similar distributions can be obtained, independent of orifice diameter, if momentum-flux ratio and orifice spacing are coupled; (3) a first-order approximation of the mixing of jets with a variable-temperature main stream can be obtained by superimposing the main-stream and jets-in-an-isothermal-crossflow profiles; (4) the penetration of jets issuing mixing is slower and is asymmetric with respect to the jet centerplanes, which shift laterally with increasing downstream distance; (5) double rows of jets give temperature distributions similar to those from a single row of equally spaced, equal-area circular holes; (6) for opposed rows of jets, with the orifice centerlines in line, the optimum ratio of orifice spacing to duct height is one-half the optimum value for single-side injection at the same momentum-flux ratiol and (7) for opposed rows of jets, with the orifice centerlines staggered, the optimum ratio of orifice spacing to duct height is twice the optimum value for single-side injection at the same momentum-flux ratio