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.

Nozzle‐quenching process for controlled flame synthesis of titania nanoparticles

Abstract: A process for precisely controlled synthesis of nanoparticles with a broad range of sizes, morphologies, and phase compositions is presented. This is achieved by a rapid quenching of the entire flame aerosol in a critical-flow nozzle placed above and into the flame. This process is evaluated for synthesis of titania nanoparticles by oxidation of titanium-tetra-isopropoxide (TTIP) in a methane/oxygen coflow diffusion-flame reactor. Precise control of phase composition from 97 to 5 wt. % anatase (and the balance rutile) and average primary particle diameter from 5 to 60 nm is possible by positioning the quenching nozzle at the desired heights above the burner and controlling gas and precursor flow rates. The nozzle quenching also reduces the degree of agglomeration of the product particles. An operation diagram shows that the primary particle diameter and the phase composition can be independently controlled, making anatase or rutile nanoparticles with high or low specific surface area.

Numerical Analysis of Nozzle Material Thermochemical Erosion in Hybrid Rocket Engines

Abstract: Ablative materials are commonly used to protect the nozzle metallic housing and to provide the internal contour to expand the exhaust gases in both solid and hybrid rockets. Because of interaction with hot gas, these materials are chemically eroded during rocket firing, with a resulting nominal performance reduction. The objective of the present work is to study the erosion behavior of graphite nozzles in hybrid engines at different operating conditions and compare results with those obtained for solid motors. A main distinctive feature of hybrid engine operating conditions is, in fact, a greater concentration of oxygen-containing combustion products than solid motors. The adopted approach relies on a validated full Navier–Stokes flow solver coupled with a thermochemical ablation model that takes into account heterogeneous chemical reactions at the nozzle surface, rate of diffusion of the species through the boundary layer, ablation species injection in the boundary layer, heat conduction inside the nozzl...

Method and device for coating

Abstract: The invention relates to metallurgy. The proposed method for coating of articles provides for introducing into a gas flow the powder of a material chosen from a group consisting of metals, alloys and their mechanical mixtures, or dielectrics, and having a particle size of 1 to about 50 νm, in a quantity sufficient to ensure a mass flux density of the particles of 0.05 to 17 g/sec.cm2, so as to form a gas-powder mixture which is directed on the surface of the article, the gas flow being given a supersonic speed and being formed into a supersonic jet of a desired profile providing for a speed of the powder particles in the gas-powder mixture of 300-1,200 m/sec. A device for implementation of the method comprises a doser-feeder (1) and, interconnected to each other, a bunker (2) for the powder, a means for dosing it consisting of a horizontally mounted drum (9) with recesses provided along a spiral line on its cylindrical surface (9'), a mixing chamber (3), a nozzle (4) intended for acceleration of the powder particles and connected to the mixing chamber (3), a compressed air source (5) connected to a means for feeding the compressed air to the mixing chamber (3), a flow regulator (11) for the powder particles mounted in relation to the cylindrical surface (9') of the drum (9) with a gap (12) ensuring the required mass flow of the powder, an intermediate nozzle (13) coupled with the mixing chamber (3) and connecting through its inlet pipe (8) to the means for feeding the compressed air, and a baffle (15) mounted on the bottom of the bunker (2) and in close proximity to the cylindrical surface (9') of the drum, the nozzle (4) for acceleration of the powder particles having a supersonic design and being provided with a profiled channel (18).

Apparatus and process for producing high density thermal spray coatings

Abstract: An attachment for supersonic thermal spray equipment by which inert shield gas is directed radially outwardly about the central core of a supersonic, particle-carrying flame to isolate the same from ambient atmosphere. The shield gas is injected tangentially against the inner surface of a constraining tube attached to and extending from the discharge end of the thermal spray gun nozzle, causing the shield gas to assume a helical flow path which persists until after it exits the tube and impacts the work piece. A process using the shielding apparatus with a high-velocity, thermal spray gun and employing oxygen and hydrogen as gases of combustion and inert gas to introduce metal powder, having a narrow particle size distribution and low oxygen content, into the high-velocity combustion gases, produces significantly improved, high-density, low-oxide metal coatings on a substrate.

Suspension for the pivoting vane actuation mechanism of a variable nozzle turbocharger

Abstract: An improved suspension for a pivoting vane actuation mechanism is incorporated into a variable nozzle turbicharger in order to prevent vane binding. The mechanism includes a plurality of rotatable vanes mounted to a nozzle ring and a means for rotating the plurality of vanes. The nozzle ring and the means for rotating are coupled together so that thermal growth does not cause misalignment of the two.