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.

New technique for determination of internal geometry of a diesel nozzle with the use of silicone methodology

Abstract: A new technique has been presented to characterize the internal geometry of diesel injection nozzles. This technique is based on the impression of silicone molds. The advantages of this technique, compared with other techniques, are that it is possible to see and measure internal zones of the nozzle like the inlet curvature radius, and it is a non-destructive method. The technique has been validated, with positive results.

Solution of the quasi-one-dimensional linearized Euler equations using flow invariants and the Magnus expansion

Abstract: The acoustic and entropy transfer functions of quasi-one-dimensional nozzles are studied analytically for both subsonic and choked flows with and without shock waves. The present analytical study extends both the compact nozzle solution obtained by Marble & Candel (J. Sound Vib., vol. 55, 1977, pp. 225–243) and the effective nozzle length proposed by Stow, Dowling & Hynes (J. Fluid Mech., vol. 467, 2002, pp. 215–239) and by Goh & Morgans (J. Sound Vib., vol. 330, 2011, pp. 5184–5198) to non-zero frequencies for both modulus and phase through an asymptotic expansion of the linearized Euler equations. It also extends the piecewise-linear approximation of the velocity profile in the nozzle proposed by Moase, Brear & Manzie (J. Fluid Mech., vol. 585, 2007, pp. 281–304) to any arbitrary profile or equivalently any nozzle geometry. The equations are written as a function of three variables, namely the dimensionless mass, total temperature and entropy fluctuations, yielding a first-order linear system of differential equations with varying coefficients, which is solved using the Magnus expansion. The solution shows that both the modulus and the phase of the transfer functions of the nozzle have a strong dependence on the frequency. This holds for both choked flows and subsonic converging–diverging nozzles. The method is used to compare two different nozzle geometries with the same inlet and outlet Mach numbers, showing that, even if the compact solution predicts no differences between the transfer functions of the two nozzles, significant differences are found at non-zero frequencies. A parametric study is finally performed to calculate the indirect to direct noise ratio for a model combustor, showing that this ratio decreases at higher frequencies.

Self-ignition and explosion during discharge of high-pressure hydrogen

Abstract: The phenomenon of self-ignition and explosion during discharge of high-pressure hydrogen was investigated. To clarify the ignition conditions of high-pressure hydrogen jets, rapid discharge of the high-pressure hydrogen was examined experimentally. A diaphragm was used to allow rapid discharge of the high-pressure hydrogen. The burst pressure was varied from 4 to 30 MPa. The downstream geometry of the diaphragm was a flange and extension pipes, with the pipe length varying from 3 to 300 mm. The diameter of the nozzle was 5 or 10 mm. When short pipes were used, the hydrogen jet did not ignite. However, the hydrogen jet showed an increasing tendency to ignite in the pipe as the length of the pipe became longer. At higher burst pressures, a diffusion jet flame was formed from the pipe. The blast wave from the fireball formed on self-ignition of the hydrogen jet resulted in an extremely rapid pressure rise.

Application of Exhaust Gas Recirculation in a DLN F-Class Combustion System for Postcombustion Carbon Capture

Abstract: This paper describes experimental work performed at General Electric, Global Research Center to evaluate the performance and understand the risks of using dry low NO x (DLN) technologies in exhaust gas recirculation (EGR) conditions. Exhaust gas recirculation is viewed as an enabling technology for increasing the CO 2 concentration of the flue gas while decreasing the volume of the postcombustion separation plant and therefore allowing a significant reduction in CO 2 capture cost. A research combustor was developed for exploring the performance of nozzles operating in low O 2 environment at representative pressures and temperatures. A series of experiments in a visually accessible test rig have been performed at gas turbine pressures and temperatures, in which inert gases such as N 2 /CO 2 were used to vitiate the fresh air to the levels determined by cycle models. Moreover, the paper discusses experimental work performed using a DLN nozzle used in GE's F-class heavy-duty gas turbines. Experimental results using a research combustor operating in a partially premixed mode include the effect of EGR on operability, efficiency, and emission performance under conditions of up to 40% EGR. Experiments performed in a fully premixed mode using a DLN single nozzle combustor revealed that further reductions in NO x could be achieved while at the same time still complying with CO emissions. While most existing studies concentrate on limitations related to the minimum oxygen concentration (MOC) at the combustor exit, we report the importance of CO 2 levels in the oxidizer. This limitation is as important as the MOC, and it varies with the pressure and firing temperatures.

Axial flow turbine

Abstract: An axial flow turbine provided with a stage composed of a turbine nozzle and a turbine rotor blade arranged in an axial flow direction. Both end portions of a nozzle blade of the turbine nozzle are supported by a diaphragm inner ring and a diaphragm outer ring, and a flow passage is formed to have its diameter expanded from an upstream stage to a downstream stage. In such axial flow turbine, trailing edges at ends of the nozzle blade supported by the diaphragm inner ring and the diaphragm outer ring are curved as a curvature to an outlet side, and an intermediate portion between the trailing edges is formed to be straight.