Nozzle

About: Nozzle is a research topic. Over the lifetime, 158675 publications have been published within this topic receiving 893026 citations. The topic is also known as: spout.

Adhesive spray gun and nozzle attachment

Abstract: An apparatus for spraying heated hot melt adhesive in elongated strands or fibers in a controlled, spiral pattern upon a substrate comprises a spray gun having a nozzle formed with an adhesive delivery passageway and an air delivery passageway both of which terminate at the base of the nozzle. A nozzle attachment in the form of an annular plate is mounted to the base of the nozzle by an end cap. The annular plate is formed with a throughbore which receives hot melt adhesive from the adhesive delivery passageway and ejects an adhesive bead through a nozzle tip formed on the plate. An annular groove formed in the plate facilitates the drilling of air jet bores therein at an angle relative to the throughbore and adhesive bead ejected therefrom. The air jet bores receive pressurized air from the air delivery passageway and direct the pressurized air substantially tangent to the adhesive bead to form elongated adhesive fibers and to impart a spiral motion to the elongated fibers so that they are formed in a compact spray pattern for deposition onto a substrate.

Dynamics of an impinging jet. Part 1. The feedback phenomenon

Abstract: In a high-speed subsonic jet impinging on a flat plate, the surface pressure fluctuations have a broad spectrum due to the turbulent nature of the high-Reynolds-number jet. However, these pressure fluctuations dramatically change their pattern into almost periodic waves, if the plate is placed close to the nozzle (x0/d < 7·5). In the present study extensive measurements of the near-field pressure provide solid support for the hypothesis that a feedback mechanism is responsible for the sudden change observed in the pressure fluctuations at the onset of resonance. The feedback loop consists of two elements: the downstream-convected coherent structures and upstream-propagating pressure waves generated by the impingement of the coherent structures on the plate. The upstream-propagating waves and the coherent structures are phase-locked at the nozzle exit. The upstream-propagating waves excite the thin shear layer near the nozzle lip and produce periodic coherent structures. The period is determined by the convection speed of the coherent structures, the speed of the upstream-propagating waves as well as the distance between the nozzle and the plate. An instability process, herein referred to as the ‘collective interaction’, was found to be critical in closing the feedback loop near the nozzle lip.

Velocity Distributions in Molecular Beams from Nozzle Sources

Abstract: The velocity distributions in molecular beams of argon produced by the Kantrowitz‐Grey supersonic nozzle technique have been investigated using a time‐of‐flight method It is shown that the transition from continuum to free molecular flow in free jet expansion limits the minimum width of the velocity distribution which may be obtained The Mach number corresponding to the axial velocity distribution of the expanding gas approaches a limit which varies inversely with the two‐fifths power of the Knudsen number at the nozzle With argon at room temperature the narrowest velocity distribution obtained corresponds to a Mach number of 23 (90% of the molecules within 54% of the most probable velocity)

Ink jet head and a method of manufacturing thereof

Abstract: A casing and a nozzle plate form a hollow cavity in which ink liquid can be filled. A buckling structure body is disposed within this hollow cavity. A nozzle orifice is provided in a nozzle plate at a position corresponding to the buckling structure body. The buckling structure body has a portion extending in a longitudinal direction. Both ends of the buckling structure body in the longitudinal direction are fixedly attached to the casing via an insulative member. The buckling structure body is formed of a material that is displaced at least in the longitudinal direction by conduction of current from a power source. Thus, an ink jet head of a long lifetime is provided that can provide a great discharge force while maintaining its small dimension.

Direct experimental determination of laminar flame speeds

Abstract: The stability of premixed flames at ultralow strain rates was assessed experimentally and numerically in the stagnation flow configuration. Results indicate that there are inherent limitations in establishing weakly strained planar flames, and that the accuracy of the laminar flame speeds obtained through linear extrapolations can, thus, be compromised. In view of these limitations, a new methodology is proposed for the direct experimental determination of laminar flame speeds. It includes the use of the stagnation flow configuration and large separation distances betwenn the nozzle and the stagnation plane, which allow for the establishment of Bunsen-type flames as the flow rate is reduced. The flow velocities are measured by using laser Doppler velocimetry. The proposed technique is based on the principle that whereas the planar, strained flames are positively stretched, the Bunsen flames are negatively stretched. Thus, by achieving a smooth, quasi-steady transition between planar and Bunsen flames, the flames pass through a near-zero strain-rate state. Real-time LDV measurements were obtained at numerous fixed spatial locations in the region within which transition occurs. The minimum velocity obtained in these measurements corresponds to the flame speed at the limit of near-zero stretch and is proposed as a representative value of the true laminar flame speed, SHo. Laminar flame speeds were obtained for atmospheric CH4/air, C2H6/air, and C3H8/air mixtures and for a wide range of equivalence ratios. The new Sno values were found to be systematically lower than the values that have been determined by using the traditional stagnation flow technique and linear extrapolations to zero strain rate.