Influence Of Nozzle Structure Research Articles

Influence of nozzle structure on effectiveness of jet grouting operations and its optimal design

The jet grouting technique is gradually adopted for improving gas production from reservoirs yielding a low permeability. Ensuring the quality of jet grouting products involves optimizing the efficiency of jetting gear including nozzle. This paper investigates the effect of nozzle structure on efficiency of jet flow and delineates the optimal nozzles for jet grouting operations. A tri-fold approach was adopted including field experiment, numerical simulation, and multicriteria decision analysis. The numerical and experimental results show that, of the 10 structures investigated, 4 achieved a steadiest jetting pressure attenuation along different standoff distances, whilst satisfying the requirement of driving pressure of 30 MPa with a flow rate of 70–80 L/min. The converging section plays a critical role in the conversion of viscous force within the nozzle. The study shows that the dominant flow regime is governed by the nozzle's parameters L2 and θ and the optimal structure of the nozzle has been designed, i.e., d = 2.4 mm; θ = 26°; D = 4.24 mm; L1= 10 mm; L2 = 4 mm; and L3 = 21.10 mm. The numerical results agree well with the experimental observations, proving that the optimal design can be adopted for enhancing jet grouting operations.

Influence of nozzle structure on the flow field of the prestage of nozzle flapper servo valve

Influence of nozzle structure on the flow field of the prestage of nozzle flapper servo valve

Influence of nozzle structure on the combustion performance of a graphitic hydrogen-chlorine synthesis combustor

The growing semiconductor sector is driving up demand for high-purity gas-phase HCl. Large combustion zones and low HCl concentrations are problems for HCl manufacturing systems. Based on the realizable k-ε model, the eddy breakup combustion model, and the participating media radiation model, the computational fluid dynamics simulation was used as the primary means in this study. The influence of four structural factors, nozzle jet hole diameter, jet angle, and opening angle—another is nozzle mounting height, on the combustion effect of the synthesis combustor was investigated. The extent of the high-temperature zone in the synthesis combustor and the purity of the hydrogen chlorine at the outlet were used as the main evaluation criteria. The results of numerical simulations demonstrate that the better the gas mixing and combustion in the combustor, the lower the nozzle mounting height should be. Small nozzle diameters and large nozzle jet angle increase gas flow velocity in the recirculation zone close to the inner wall of the combustor. Additionally, the recirculation zone will appear in the combustor as a result of the nozzle's presence. The area of the high-temperature zone within the combustor decreases as internal gas velocity increases. On the other hand, the recirculation gas flow is not significantly impacted by the angle at the condition that the jet holes open. The results of the investigation provide a reference for the design of the miniaturization of the combustor in the non-premixed combustion synthesis of gases process.

Influence of nozzle structure on the flow field of the prestage of nozzle flapper servo valve

Influence of nozzle structure on the flow field of the prestage of nozzle flapper servo valve

Effect of nozzle structure on coal breakage of SC-CO2 used for well drilling

Supercritical carbon dioxide (SC-CO2) jet is a promising technology for the extraction of coalbed methane. As a key component in the process of jet formation, the nozzle is an essential factor affecting the efficiency with which an SC-CO2 jet breaks coal and rock. The nozzle structure directly affects the energy conversion rate and flow field structure of the jet. Thus, the use of a suitable nozzle can maximize SC-CO2 energy utilization, reducing energy loss and engineering costs while achieving energy conservation and emission reduction. Based on the conical convergent nozzle and the Laval nozzles, this study conducted an SC-CO2 jet coal breakage experiment and an I-Scan pressure testing experiment using experimental research methods. The influence of nozzle structure on SC-CO2 jet coal breakage was studied and the results indicate that when the inlet pressure is constant, the Laval nozzle has a higher energy conversion rate and a stronger coal breakage effect than the conical convergent nozzle. Furthermore, considering the combined effects of the energy conversion rates of Laval nozzles and energy dissipation under ambient pressure, a key parameter for assessing Laval nozzles was discovered: the expansion ratio. The results indicate that the impact of jet temperature on the expansion ratio is small and that increasing the erosion effect of an SC-CO2 jet by increasing the jet temperature is an energy-consuming and inefficient method. Essentially, the optimum coal breakage effect of the SC-CO2 jet is obtained when the expansion ratio of the Laval nozzle is between 1.07 and 1.29.

Influence of nozzle structure on the consumption of shielding gas in the gas metal arc welding process

To reduce the consumption of gas metal arc welding shielding gas and improve welding quality, three spiral-diffusion nozzles with different structures were designed in this study. The four evaluation indexes of the flow field quality of shielding gas were determined by analyzing the protective airflow field with the computational fluid dynamics simulation method. Isight software was used to optimize the multi-objective parameters of the three spiral-diffusion nozzles with the self-adaptive mutation genetic algorithm. Combined with the computational fluid dynamic simulation results, the optimized value of each nozzle and the percentage of parameters such as gas reduction were obtained. Three new double-helical spiral-diffusion stainless nozzles were created using 3D printing, and the gas metal arc welding of the Q235 and A36 steel plates was performed using 80% Ar + 20% CO2 mixed shielding gas with three nozzles. The tensile test and impact test were conducted to inspect tensile strength and impact toughness, and the hardness and average grain grade of microstructures in the weld seam were analyzed. The experimental results were consistent with the optimization simulation results. In terms of welding quality, compared with the shielding gas consumption of the conventional nozzle, that of the optimized spiral-diffusion nozzles I, II, and III could be reduced by 29.22%, 33.19%, and 27.31%, and the effective protection range could be increased by 34.53%, 19.79%, and 19.69%, respectively.

Comparison of numerical analysis on the downhole flow field for multi-orifice hydrothermal jet drilling technology for geothermal wells

Newly developed hydrothermal jet drilling technology has the potential of being economically advantageous over conventional drilling techniques for drilling deep wells in hard formations. By applying coiled tubing techniques and modulating fluid media in the bottomhole reaction chamber, there can be a high temperature and high velocity jet striking and conducting heat to break the rock. So far, there has been no specific study on the influence of nozzle structure on the flow field of multiple hydrothermal jets. This paper presents hydrothermal jet models with different numbers of orifices to investigate the features of flow field, carrying capacity, drilling ability and cooling effect. Results show that for two models in the absence of cooling water, the bottomhole center temperature and pressure are higher than the two sides under multiple hydrothermal jets conditions. This is similar to the flow pattern for a single jet. Additionally, for the five-orifice nozzle with cooling water injected, the entire high temperature region is cylindrical. Ambient cooling water envelops the inner hot water. By comparing different models, the five-orifice nozzle model without cooling water shows a circular symmetric distribution of the bottomhole temperature. With cooling water injected, the central high temperature region becomes rectangular, while the margin of the well bottom is cooled by the peripheral cooling water. The bottom rock average temperature in five-orifice model is lower than for the four-orifice model due to more drastic thermal and kinetic transfer between the hydrothermal jet and the cooling water. The five-orifice nozzle model is better than the four-orifice nozzle model in terms of bottomhole temperature, bottomhole pressure and carrying capacity. Therefore, the five-orifice nozzle should be adopted for hydrothermal jet drilling. It is also feasible to pump down relatively high temperature cooling water to guarantee the high temperature downhole environment. Meanwhile, the cooling water pressure should be controlled during the drilling process for better cooling efficiency. All results in this paper are relevant to the parameters design for multi-orifice hydrothermal jet drilling technology.

Study on Influence of Nozzle Structure on Flow in Diesel Nozzle Orifice

The fuel flow characteristics in diesel nozzle orifice are key factors to the atomization of fuel near the nozzle orifice. In the paper, two-phase flow model is used to simulate the complex flow features in nozzle orifice, and to study the influences of the relative position of nozzles orifice axis and nozzle axis, and inclination angle of nozzle hole on the internal flow feature.

Three-dimensional FEM study of fluid flow in mould for beam blank continuous casting: influence of nozzle structure and parameters on fluid flow

The aim of this work was to analyse the influence of the nozzle structure and parameters on the molten steel flow in beam blank continuous casting. A three-dimensional steady state finite element model was developed to compute the flow field and the meniscus fluctuation in the mould. The volume of fluid model was used to track the free surface evolution at the meniscus. It can be concluded that compared with a through conduit submerged entry nozzle (SEN), a three lateral hole SEN will reduce the impact depth, change greatly the velocity at the free surface and intensify the fluctuation of the free surface. As a whole, the fluid flow in the mould will be improved, which will help to melt the mould powder and improve the absorption of non-metallic inclusions, thus improving steel cleanness. The most rational rake angle for the three lateral hole SEN is 9°. Meanwhile, the SEN immersion depth should be in the range 200–250 mm if the casting speed is about 0·9–1·1 m min−1.

Study on gas–liquid two-phase spraying characteristics of nozzles for the humidification of smoke

In the present paper, an experimental investigation of the humidifying and desulfuration of flue gas by water spraying is conducted in order to increase the ability of the self-desulfuration efficiency of Ca composition in coal in a power plant boiler. The experimental facility, nozzle structure, measurement method and instruments are introduced. The influence of nozzle structure, the way to enter the liquid and the ratio between phases on the spray characteristics including size distribution of the droplet and spray angle is studied. The results show significant variation and show how to optimize the design and operation of the nozzles.