Kinds Of Nozzles Research Articles

Optimization of Process Parameters for Flow Nozzle with Different Geometry using Computational Fluid Dynamics Method

A nozzle is a tubular structure designed to facilitate the flow of hot gases. Rocket nozzle designs typically consist of a stationary convergent section and a stationary divergent section. The term "CD" is an abbreviation for "convergent-divergent" and is used to refer to this specific nozzle type. Upgrades are being made to nozzles and other engine components in order to enhance performance and optimise thrust delivery. Application-specific improvements will be made to rocket nozzles and other current combustion expansion systems. An instance of such progress is the implementation of the bell and twin bell nozzle. This study conducted a comparative analysis of two kinds of nozzles, namely bell and conical, at different Mach speeds to ascertain which one yields the most optimal flow. Subsequently, the flow parameters were modelled with computational fluid dynamics (CFD). Ensuring optimal pressure thrust integral throughout the supersonic zone of the nozzle surface while taking the base pressure into account was the aim of the problem formulation. The research focused on irrotational flow, taking into consideration the impacts of boundary layers.

A two-phase density-based solver for simulating wet steam flows with non-equilibrium condensation. I. Approach and verification

This paper presents a new two-phase density-based solver based on the finite difference method for simulating high-speed wet steam flows with non-equilibrium condensation. The solver employs the Eulerian–Eulerian approach to model the wet steam flow using a fifth-order accurate weighted compact nonlinear scheme. The phase change of wet steam involves droplet growth in a non-equilibrium condensation process based on the internally consistent classical theory. To speed up computation, a tabulated equation of state approach with curvilinear grids is developed, and an improved Harten-Lax–van Leer-contact-type Riemann solver is used to compute inviscid fluxes. Furthermore, the automatic differentiation technique is applied to avoid manually deriving complicated derivatives when computing flux Jacobian matrices and thermodynamic properties. A numerical investigation is conducted on flow via various kinds of nozzles and blades, and the results demonstrate that the numerical model accurately predicts the behaviors observed in the experiments.

An Analysis of Jet Noise Characteristics in the Compressible Turbulent Mixing Layer of a Standard Nozzle

In this paper, we seek to understand the influence of TPS standard nozzle shape on jet noise and improve the accuracy of flow and pressure ratio of aeronautical simulation. Through the structural design of an equal-diameter nozzle and a standard nozzle, a concentric dichotomy monitoring point arrangement scheme is proposed for its flow field and sound field, and the free flow of the jet is used to realize k − ε. The model is solved by hydrodynamics to analyze the flow characteristics of the turbulent boundary layer, and the near-field and far-field characteristics of jet noise are analyzed by using the Lighthill equation excited by a quadrupole under fluid input, revealing the turbulent velocity and turbulent kinetic energy and other relevant fluid characteristics of the two nozzles under a single variable, and analyzing the near-field and far-field noise pressure levels and directivity of the two nozzles at a specific frequency. When the boundary conditions are consistent, the change trends and laws of the two kinds of nozzles in the turbulent jet flow field are almost the same, and the eddy viscosity extreme value of the standard nozzle is 0.02 higher than that of the equal-diameter nozzle, while the static temperature extreme value is 8 K, but they have a great impact in the noise field, mainly reflected in the noise decreasing law, noise directivity and low-frequency noise distribution. The mean value of noise extremes of standard nozzles at four frequencies is 2 dB higher than that of equal-diameter nozzles. The relative characteristics of the two nozzles can be used to design through the actual demand conditions of the flow field and the sound field by providing a reference for the customized parameter design of the standard nozzle.

Orthogonal Optimization Research on Various Nozzles of High-Speed Centrifugal Spinning.

High-speed centrifugal spinning is a burgeoning method of fabricating nanofibers by use of the centrifugal force field. This article studied four different spinning nozzles, which were called stepped nozzle, conical-straight nozzle, conical nozzle, and curved-tube nozzle, to explore the optimal nozzle structures for fabricating nanofibers. According to the principle of centrifugal spinning, the spinning solution flow states within the four nozzles were analyzed, and the solution outlet velocity model was established. Then, the structural parameters of the four kinds of nozzles were optimized with the spinning solution outlet velocity as the test index by combining the orthogonal test and numerical simulation. Based on the orthogonal test results, the influence of nozzle structure parameters on the solution outlet velocity was analyzed, and the best combination of parameters of the centrifugal spinning nozzle structure was obtained. Subsequently, the four kinds of nozzles were used to fabricate nanofibers in the laboratory, under different solution concentration, motor rotation speed, and outlet diameters. Finally, the scanning electron microscope (SEM) was applied to observe the morphology and surface quality of nanofibers. It was found that the surface of nanofibers manufactured by the conical-straight nozzle and curved-tube nozzle was smoother than that by stepped and conical nozzles, and the fiber diameter by the conical-straight nozzle was minimal, followed by curved-tube nozzles, stepped nozzles, and conical nozzles in the diameter distribution of nanofibers.

Morphology and Efficiency of the Deposition Function in the Deterministic Electrochemical Repairing Method

Deterministic electrochemical repairing method is effective technique for the rapid fixing of damaged parts in the military equipment, and its critical content is to achieve a steady deposition function. In order to take into consideration both the repairing efficiency and fixing accuracy, three shapes of deposition functions were developed through the square nozzles, the rectangular nozzles and the round nozzles. Meanwhile, for the three kinds of nozzles, each kind had several sizes, which aimed to further improve the scope of application of the deterministic electrochemical repairing method. Furthermore, the deposition functions were detected through measuring the morphology and efficiency of the deposition spots obtained by the deterministic electrochemical repairing system with the varied deposition times of 0.5h, 1.0h, 1.5h and 2.0h, respectively. The experimental results indicated that morphology of the deposition functions were consistent with those theoretical results, and their corresponding efficiency was steady, which were propitious to obtained better repairing efficiency and higher fixing accuracy. The developed effective deposition functions can promote the practical application of deterministic electrochemical repairing method in the precision assurance of military equipment.

Theoretical and experimental investigations of different area ratios of a supersonic ejector driven by compressed air

AbstractEjectors have some advantages such as being simple, reliable and no moving parts. They can be used in air-conditioning and refrigeration applications. This paper presents a comparison of ejector performance, primary pressure (Pp), back pressure (Pb) and area ratios of ejectors (A2/At) predictions by an analytical model and a computational fluid dynamics model for different operating conditions. Six different area ratios of ejector using air as working fluid in this study were proposed and tested experimentally. The variable area ratios of ejectors (A2/At) were used with a range from 10.68 to 30.62. Two sets of ejectors (A and C) are studied and examined depend on the kind of nozzle. The aim of this study was to investigate these ejectors under variation of primary pressure (Pp) (1.5–6.0 bar) and adjustable spindle position (0 to −25 mm). Two groups of ejectors (A and C) were categorized based on the type of nozzle. The experimental results validate the solutions of the main parameters of ejectors using air as working fluid. The results show that group A is more appropriate for higher values of back pressure, while group C is more suitable for high performance of the ejector. Finally, the main parameters were carried out on six different ejectors to find the best combination based on various nozzles and constant area sections.

How the nozzle position affects the geometry of the melt pool in directed energy deposition process

ABSTRACTThis work deals with Directed Energy Deposition (DED) that is a process in which the material is delivered directly into the melt pool. Several kinds of nozzle have been developed and used in this process. However, the position of the nozzle, mainly for the lateral one, plays a crucial role in the geometry and porosity content of the melt pool. Therefore, to investigate the correlation between the lateral nozzle position and the geometry of the melt pool, three different sets of single tracks of Ti–6Al–4V were deposited at different nozzle positions. It was found that helpful information regarding the selection of the optimal position of the lateral nozzle can be obtained from the melt pool features. It can be noticed that by increasing the distance between the nozzle position and substrate, the powder capture decreases and accordingly results in a high depth of fusion zone and also keyhole defect formation.

Reduction of shielding gas dosage in GMAW process

In order to reduce productioncost, it is necessary to reduce the quantity of shielding gas under ensuring the quality of welding jointsin gas metal arc welding (GMAW) process. Three nozzles,spiral nozzle, shrink nozzle and diverging nozzle, with different geometric structurewere designed to compare with industrial normal nozzle. The influence of the shielding gasdosageson the protectionradiusforfour types of nozzles were analysed through computational fluid dynamics (CFD) simulation, and the minimum dosage of shielding gas for different nozzles were obtained. The GMAW experiments were conducted with Q235 steel through the minimumdosage of mixture gas with four kinds of nozzles. After tensile tests of four kinds of standard welding samples, the fracture did not occur at the welding seam. So the shielding gas dosageintraditional GMAW process could be reduced greatly.

A novel spraying/negative-pressure secondary dust suppression device used in fully mechanized mining face: A case study

Aiming at improving the spraying dust suppression performances between the coal cutter hydraulic supports, a novel spraying/negative-pressure secondary dust suppression device was developed. In this device, the nozzle's atomization performance including atomizing angle, spraying range and droplet diameter were measured so as to select the optimal nozzle. A nozzle with optimal overall atomization performance was selected among 4 kinds of nozzles with hollow and solid cone-shaped spraying fields. At the optimal spraying pressure of 8MPa, the spraying field of the developed dust suppression device can almost cover all the space between coal walls and hydraulic support's columns, and effectively absorb the dusty airflow in the footway. Field measurements indicated that, compared with the original dedusting method, the dust suppression rates of total coal dust and respirable dust in the fully mechanized mining face by the developed novel spraying device can be enhanced by 26.2% and 27.3% respectively and reach efficiencies up to 82.0% and 80.9%, respectively. The dust suppression rates of total coal dust and respirable dust in the working area for supports moving workers can be enhanced to 81.5% and 80.1%, respectively.

Experimental Studies to Validate Computational Fluid Simulation of Coolant Flow Behavior through different Nozzles for Nozzle Effectiveness in Cylindrical Grinding Process to Enhance Workpiece Surface Quality

In the present paper, ANOVA (Analysis of Variance) technique has been adopted. The simulated results of flow behaviour through six different kinds of nozzles were experimentally validated to study the effect of these different types of nozzles as well as other process parameters on the response parameter namely surface roughness of ground workpiece during a cylindrical grinding process and optimized using this technique. The air flow behaviour around the rotating wheel and workpiece was simulated with computational fluid approach in ANSYS CFX. The optimum solution was found coherent with the simulated results. Spline type nozzle followed by convergent-divergent type was found the two best nozzles. Optimized solution also indicated the best parametric setting for the optimum results.

Structure Optimization and Numerical Simulation of Nozzle for High Pressure Water Jetting

Three kinds of nozzles normally used in industrial production are numerically simulated, and the structure of nozzle with the best jetting performance out of the three nozzles is optimized. TheR90 nozzle displays the most optimal jetting properties, including the smooth transition of the nozzle’s inner surface. Simulation results of all sample nozzles in this study show that the helix nozzle ultimately displays the best jetting performance. Jetting velocity magnitude alongYandZcoordinates is not symmetrical for the helix nozzle. Compared to simply changing the jetting angle, revolving the jet issued from the helix nozzle creates a grinding wheel on the cleaning surface, which makes not only an impact effect but also a shearing action on the cleaning object. This particular shearing action improves the cleaning process overall and forms a wider, effective cleaning range, thus obtaining a broader jet width.

The Selection of Ceramic Dry Granulating Machine Spray Device Based on the DPM Model

In order to improve the dispersity of true particles in the process of ceramic dry granulation, by adding a sprayer in the upper of granulation chamber to make water spray into droplets, which greatly increases the contact area of liquid water and powder. The atomization flow field of plain-orifice-nozzle, pressure-swirl-nozzle, air-blast-nozzle, effervescent-nozzle with 1mm nozzle diameter is simulated based on the DPM model, obtaining the droplet size distribution cloud picture and atomization flow field simulative cloud picture of four kinds of nozzle. The simulation results show that the average droplet size of pressure-swirl-nozzle is the minimum and the disperisity of atomization flow field of air-blast-nozzle, effervescent-nozzle, pressure-swirl-nozzle, plain-orifice-nozzle increases in turn. In terms of the average droplet size and the dispersity of atomization flow field, the droplet dispersity of pressure-swirl-nozzle is better and the average droplet size is the minimum, which is most beneficial to solve the problem of fully dispersity of really particle. Therefore, pressure-swirl-nozzle is best fit for the spray device of ceramic dry granulation.

Short Spray Penetration for Direct Injection Gasoline Engines With Secondary-Drop-Breakup Simulation Integrated With Fuel-Breakup Simulation

Direct injection gasoline engines have both better engine power and fuel efficiency than port injection gasoline engines. However, direct injection gasoline engines also emit more particulate matter (PM) than port injection gasoline engines do. To decrease PM, fuel injectors with short spray penetration are required. More effective fuel injectors can be preliminarily designed by numerically simulating fuel spray. We previously developed a fuel-spray simulation. Both the fuel flow within the flow paths of an injector and the liquid column at the injector outlet were simulated by using a grid method. The liquid-column breakup was simulated by using a particle method. The motion of droplets within the air/fuel mixture (secondary-drop-breakup) region was calculated by using a discrete droplet model (DDM). In this study, we applied our fuel-spray simulation to sprays for the direct injection gasoline engines. Simulated spray penetrations agreed relatively well with measured spray penetrations. Velocity distributions at the outlet of three kinds of nozzles were plotted by using a histogram, and the relationship between the velocity distributions and spray penetrations was studied. We found that shrinking the high-speed region and making the velocity-distribution uniform were required for short spray penetration.

Hydrodynamics of the Aluminium Barbotage Process Conducted in a Continuous Reactor

Today aluminium obtained from ores (primary) and from scrap (secondary) need to be refined. During this process harmful impurities such as hydrogen, sodium, lithium, oxides, borides or carbides can be removed. There are many different ways of aluminium refining process. The most popular seem to be barbotage that means blowing through aluminium many tiny gas bubbles of refining gas. Reactors applying this methods have been working all over the word. They are of different types: bath and continuous, using ceramic porous plugs, special kinds of nozzles or rotary impeller for generating small gas bubbles. At present reactors for continuous refining have become the most popular. In Poland typical representative of such reactors is URC-7000 reactor. The phenomena occurring during this process are rather complicated. Therefore to know them better the modelling research is applied, especially physical modelling. The paper presents the results of such a research. The tests were carried out in the test stand for modelling the babotage process in the URC-7000 reactor. The different modelling agents were tested (water, glycerin and mixture of water and glycerine). The density and viscosity of water and glycerin mixture were determined. Modelling tests were conducted for four different flow rates of refining gas: 6, 10, 15 and 20 dm3/min. Results were registered by digital camera. Pictures for different modelling agents were juxtaposed and discussed.

Design of Sand Washing and Plug Removal Device with High Pressure Foam Fluid Jet

In the oil and gas production process, serious sand production causes reservoir and pipe blocked, which makes productivity declined, even stopped. It's the efficient means of sand washing and plug removal by using high-pressure foam fluid jet. The structure and performance of sand washing device determines the efficiency of sand washing and plug removal. The device's nozzle consists of anti-blocking valves, three kinds of nozzles with self-drive, rotation characteristics during the operation. The nozzles include sand washing nozzle, couple nozzle and power nozzle. This device can be used in horizontal wells with complex well bore situation to carry out sand and plug removal. The device has a good effect on sand washing and plug removal in the oil field.

Investigation of the injection process and combustion of a dimethyl ether engine with different nozzle flow areas

Dimethyl ether (DME) is a promising alternative fuel, which can be used as a substitute for fossil diesel fuels, with a smaller lower heating value. When used in diesel engines, the nozzle flow area (i.e. the number of nozzle holes × nozzle hole diameter) of the engine is normally increased to maintain the engine power. In this study, three kinds of nozzle (with nozzle flow areas of 5 × 0.30 mm, 5 × 0.35 mm, and 5 × 0.40 mm respectively) were prepared. With a two-cylinder diesel engine, the effects of the nozzle flow area on the DME injection process and combustion characteristics were investigated. The experimental results indicate that the DME acoustic velocity shows no variation with the change in the nozzle hole diameter and that the DME injection timing is not affected. However, as the nozzle hole diameter increased, the DME line pressure (and, in particular, the second peak of the line pressure on the nozzle side) is greatly decreased. Meanwhile, the fall of the needle valve lift is advanced, resulting in a decrease in the injection duration. Further, the engine ignition delay is slightly increased, the total combustion duration is slightly shortened, and the engine brake thermal efficiency is slightly elevated.

Experimental study on hysteresis phenomena of shock wave structure in an over-expanded axisymmetric jet

In recent studies on two-dimensional supersonic jets, it is reported that the hysteresis phenomenon for the reflection type of shock waves in the jet flow field is occurred under the quasi-steady flow condition and this phenomenon is affected by the transitional pressure ratio between the regular reflection and Mach reflection. However, so far, there are few researches on the hysteresis phenomenon for the transition of shock waves between regular and Mach reflection in over-expanded supersonic jets and the phenomenon has not been investigated satisfactorily. Therefore, the purpose of this study is to clarify the hysteresis phenomena for the reflection type of shock wave in the over-expanded axi-symmetric supersonic jet experimentally, and to discuss the relationship between hysteresis phenomenon and rate of the change of pressure ratio with time. Furthermore, the effect of Mach number at the nozzle exit on hysteresis loop was investigated for two kinds of nozzle.

Effect of Hardness of Needle-Sealing Surface of Pintle Nozzle on Cavitation Erosion

Nozzle is one of key parts in the diesel engine. The cavitation erosion of needle-sealing surface in the pintle nozzle has important influence on the fuel atomization, combustion and power performance of diesel engine. In order to investigate the effect of hardness of needle-sealing surface on cavitation erosion, two kinds of nozzles were selected and operated in S195 diesel engine for 10 hours. One nozzle is heat-treated one which has lower surface hardness; the other with higher surface hardness is real commercial nozzle. The surface appearances of original and operated nozzle-sealing surface were observed by SEM. It was found that the cavitation erosion on the seal surface of nozzle with lower hardness was severer than that of nozzle with higher hardness. However, their wear ways and formations are similar.

The Structural Design of Nozzle in Outer Mixing Mode for Preparing Superfine Particles by SCF Technology

Based on the creative design of nozzle structure, the application fields of the micro-particles production using supercritical fluids (SCF) can be further broaden. According to the analysis of the structural characteristics of the nozzles, a new kind of nozzle with a tunable annular gap is proposed in this research, which includes a cover, movable trays, unmovable trays, seal fittings and connecting components. By virtue of FLUENT software, the flow field of the nozzle in outer mixing mode with two passages is numerically simulated. The effects of the passing length of SCF before mixing and the height of conic convexity on the flow-field are analyzed. The simulation results show that the above length does adverse effect on enhancing mixing extent, however, the smaller height of convexity can help achieve better mixing level. Then the nozzle is redesigned in which a movable tray and an unmovable tray are removed. The improved nozzle has simple and reasonable structure and can do better work on improving gas-liquid mixing extent.

Study of the Pressure Distribution on Nozzle Inner Wall

The nozzle,of which the efficiency has direct effects on the performance(such as endurance and speed) of watercraft,is an energy conversion component.Based on the features of isobaric surfaces,a pressure distribution model of the nozzle inner wall is built by utilizing the principle of conservation of energy.Simulation and experimental studies are carried out to investigate the inner wall pressure distributions of two kinds of nozzles(cylindrical nozzle,conical nozzle).Comparison analyses are performed among the results of the model,the simulation and the experiment.The results show ① the pressure decreases sharply near the outlet of the nozzle and the larger the diameter,the smaller the pressure gradient;② the pressure gradient of the cylindrical nozzle is larger than that of the conical nozzle;③ the pressure distribution can be well reflected by the model.