Common Nozzle Research Articles

Improved Pulsed-Jet Cleaning of Cone Filter Cartridges Using an Annular-Slit Nozzle

There is a problem with the insufficient cleaning of the dust filter cartridge by the pulsed-jet cleaning method. This paper examines the improvement in the pulse-jet performance of cone filter cartridges achieved by using an annular-slit nozzle. Off-line pulse jet experiments were conducted to study the influence of initial compressed air pressure, jet distance, and Venturi tube on injection pressure. This paper compared the filtration performance of conventional nozzles versus slit nozzles by conducting an online dust filtration-cleaning experiment and investigating the effect of a Venturi tube. The results demonstrated that the jet produced by the slit nozzle had a bigger surface area in contact with the surrounding air, enhancing the entrainment effect, boosting the overall pulsed-jet pressure, and significantly elevating the pressure in the upper and middle section of the cartridge, particularly in the upper section. In both common nozzle and slit nozzle cases, the pulsed-jet intensity initially increased and then decreased with the jet distance. The corresponding optimal jet distances were 500 mm and 400 mm, respectively. The slit nozzle provoked an increment of 16% and 44% in the pulsed-jet intensity and uniformity (to 619 Pa and 0.19), respectively. And there was an 8% reduction in residual pressure drop, a 6% improvement in fallen dust mass, and a 7% improvement in comprehensive filtration performance. The fallen dust mass produced by a single cleaning of the slit nozzle was 0.64 kg and the comprehensive filtration performance was 0.18. While the addition of a Venturi tube improved the cleaning of the filter cartridge, it also led to a higher filtration pressure drop in the dust collector and reduced comprehensive filtration performance.

Effect of ambient temperature on the jet characteristics of a swirl oxygen lance with mixed injection of CO2 + O2

Abstract O2 mixed with CO2 gas has been successfully applied in converter smelting; however, up to now, there have been few studies regarding the jet characteristics of the mixed injection of the swirl oxygen lance nozzle and the influence of different ambient temperature conditions on jet characteristics compared with common nozzles. In this study, Fluent software was used to simulate the jet characteristics of a four-hole common nozzle and a four-hole swirl nozzle under four different ambient temperature conditions to inject 95% O2 + 5% CO2 and analyze the influence of different ambient temperatures on nozzle-jet characteristics. The results show that with an increase in the ambient temperature, the jet-axis velocity and nozzle centerline speed increase. Under the same distance condition, the distance between the maximum radial velocity point of the jet and the centerline of the nozzle becomes larger, with a velocity greater than that of the swirl nozzle. However, the influence of the ambient temperature on the offset of the jet centerline is small. With an increase in the ambient temperature and distance, the jet-axis temperature increases and the temperature of the nozzle centerline decreases. The research results can provide a theoretical reference for the optimal design of a CO2 + O2 swirl oxygen lance nozzle.

Numerical study on the influence of process parameters in direct ink writing of high viscosity bio-inks

This study uses a computational fluid dynamics model to investigate the effect of direct ink writing process parameters on the quality of 3D-printed sedimentary materials. The numerical simulation employs the level-set method of the two-phase flow module of COMSOL Multiphysics software. The selected bio-ink consists of the powder portion (45s5 bio-glass and β-TCP nanoparticles) and the polymer portion (polyvinyl alcohol), which has applications in constructing biological bone scaffolds. First, the empirical results validate the extrudate shape obtained from numerical simulation. According to the observations, increasing the inlet velocity from 15 mm/s increased the extruded ink distortion, and finally, at 50 mm/s, the distortion reached its maximum. Secondly, after calibration and validation results, the role of the most common nozzles with different diameters and input speeds on the maximum ink output velocity of the nozzle is predicted. Finally, the influence of the two dimensionless parameters (the ratio of the distance between nozzle and bed to nozzle diameter and the ratio of inlet ink velocity to print speed) on the adhesion and shape of the printed layers is examined. At distances greater than 1.5 times the diameter of the nozzle, when the extrusion speed is greater (more than 1.5 times) relative to the linear speed of the nozzle, the printed filament becomes uneven. Reducing the speed ratio between 1× and 1.5× prevents the printed filament from sticking to the substrate or causing distortion.

Effects of pulsating fluid at nozzle inlet on the output characteristics of common and self‐excited oscillation nozzle

AbstractHigh‐speed water jets are key technologies for increased production efficiency in oil drilling, and high‐speed self‐excited oscillating pulsed water jets (SEOPWs) offer many advantages compared to continuous jets for most industrial applications. Therefore, many studies have focused on this topic. However, the current studies on hydraulic pulsed jets have rarely extended to integrated modeling of the high‐speed water jet transmission process. To better apply the SEOPWs, based on fluid mechanics, the theoretical model of the plunger pump–pipeline–nozzle is established, and the sensitivity of different nozzles on the pulsating fluid is studied in the time domain. Furthermore, the vibration characteristics of the nozzle are further investigated in the frequency domain. The results show that the common nozzle has an enlarged role in the pressure amplitude, the Helmholtz nozzle enlarges the pressure peak and amplitude, and the amplification is more obvious with the speedy growth on the plunger pump. However, as the pipeline becomes longer, the difference between the pressure of the inlet and outlet does not change. Therefore, the nozzle is more sensitive to the change in the plunger pump speed. In the frequency domain, the secondary frequency peak for the Helmholtz nozzle is 1.26 times larger than the interference frequency, while it is 1.08 times for the common nozzle. Helmholtz nozzles tend to produce stronger natural vibrations than common nozzles. By comparing the impact force, the experimental results show good agreement with the simulated results. The study provides a theoretical basis for water jet‐assisted drilling in deep wells and lays the foundation for the better application of self‐oscillating impact drilling tools.

Design Method for Scramjet Nozzles Under Geometric Constraints

This paper presents a novel design method for scramjet nozzles under geometric constraints. Performance optimization theory is incorporated in both the expansion flows along the ramp and the cowl. Method of characteristics is implemented to determine the nozzle configuration, and numerical methods are adopted to obtain the performance parameters and flowfield of the designed nozzle. The results denote that both the initial expansion angles of the ramp and the cowl have significant influence on nozzle performance, and there is an optimal value in the initial expansion angle of the cowl for maximum thrust. The changing tendency of axial thrust coefficient is opposite to that of lift and pitching moment, as the initial expansion angle of the ramp increases. The designed nozzle obtains significant increases of 11.14 and 917.20% in axial thrust coefficient and lift, respectively, as compared with the common nozzle designed by the truncation method. It also enhances the pitching moment by 3.90% for the trimming of the vehicle. Compared with the previous method, the scramjet nozzle obtained by the present design method can realize higher efficiencies for scramjets under geometric constraints.

Numerical Investigation of Unsteady Flow Dynamics in a Packed Bed

Numerical simulation of unsteady flow of a compressible fluid in a fixed bed filled with porous elements has been performed. The research was carried out via ANSYS Fluent software. The scientific substantiation and verification of the physical and mathematical approaches incorporated in ANSYS Fluent for the problem of unsteady flow in a fixed bed has been carried out. For the computational domain, the interfaces of the flow area and the surface of porous particles are coupled by combining the contacts into a component part. The numerical results were verified using experimental data. The study was carried out in the range of velocity from 0.25 to 3.25 m/s. An expression is proposed for determining the pressure drop in a fixed bed, in which the pressure drop depends on the velocity, flow properties and the linear coefficient of local resistance. The values of the linear coefficient of local resistance are determined for the most common nozzle shapes in the industry: cylinder, Raschig ring, convex cylinder with 7 holes, sphere with 7 holes. It was found that with an increase in velocity, the value of the linear coefficient of local resistance decreases.

Comparison of Experimental and Numerical Transient Drop Deformation during Transition through Orifices in High-Pressure Homogenizers

The droplet deformation in dispersing units of high-pressure homogenizers (HPH) is examined experimentally and numerically. Due to the small size of common homogenizer nozzles, the visual analysis of the transient droplet generation is usually not possible. Therefore, a scaled setup was used. The droplet deformation was determined quantitatively by using a shadow imaging technique. It is shown that the influence of transient stresses on the droplets caused by laminar extensional flow upstream the orifice is highly relevant for the droplet breakup behind the nozzle. Classical approaches based on an equilibrium assumption on the other side are not adequate to explain the observed droplet distributions. Based on the experimental results, a relationship from the literature with numerical simulations adopting different models are used to determine the transient droplet deformation during transition through orifices. It is shown that numerical and experimental results are in fairly good agreement at limited settings. It can be concluded that a scaled apparatus is well suited to estimate the transient droplet formation up to the outlet of the orifice.

Investigation of SARS-CoV-2 virus on nozzle surfaces of fuel supply stations in North West of Iran.

There are several ways for transmitting the SARS-CoV-2 virus to humans, and one of these ways is the contact with infected surfaces. Fuel stations have been a major concern for people and health experts due to the frequent use of common nozzles. This study was performed to identify the COVID-19 virus in the nozzles of fuel supply stations. In the current research, 25 fuel supply stations along the main street ways were investigated to recognize Coronavirus infection on the surfaces of the nozzles. For each fuel supply station, 4 nozzles were chosen (a total of 100 samples). The sampling was carried out at two periods of time, that is, before and after quarantine restrictions. Swapping was used for surface sampling, and Real-time PCR was used to determine the positive and negative results. The results showed that out of nine fuel supply stations (36 samples of nozzle surfaces), five were positive for the presence of SARS-CoV-2 on the nozzle surfaces before the corona restriction. The results showed that in the conditions after corona restriction, all samples were negative in terms of the presence of SARS-CoV-2 on the surfaces of the nozzles. In spite of the fact that gas stations can be one of the foremost inclined places for the transmission and spread of coronavirus due to the nearness and visit of individuals, but through the observance of health behaviors and implementing some procedures, cutting the transmission chain in gas stations can be facilitated.

Does polyacrylamide-based adjuvant actually reduce primary drift of airborne pesticides?

Atmospheric drift of pesticides sprayed outside treated fields may pose serious environmental and health concerns. Chemical adjuvants, among other techniques, reduce drift by modifying the physicochemical properties of the pesticide solution, which presumably produces larger droplets upon spraying that are less prone to drift. Previous studies, that have addressed the effect of adjuvants on drift reduction, mainly rely on measurements of droplet sedimentation while ignoring the presence of pesticides in the forms of small aerosols and vapor. Such forms are expected to be highly susceptible to atmospheric drift that may pose human health risk via inhalation exposure.The present study examines the effect of a polymer-based adjuvant on airborne-pesticide drift using active air sampling in two field campaigns. Surprisingly, these measurements indicate higher primary drift (PD) of airborne pesticides in the presence of adjuvant in the spraying solution. The results are further supported by comparing measured drifts to those calculated using a modified Gaussian puff dispersion model, which enabled to evaluate the impact of varying meteorological conditions during the field experiments. In addition, the adjuvant effect on droplet size distribution generated by common nozzles, was tested in a wind tunnel. The resulting size-distributions demonstrated that while the addition of adjuvant resulted in a desired shift of the volumetric distribution towards larger droplets, it also led to a significant increase in the number concentration of fine droplets. Such trends can explain how the addition of polymeric adjuvant can yield both, a reduction in sedimenting drift outside treated areas and an increase in airborne PD intensity, as observed in the present study. This study demonstrates the complex effect of chemical adjuvants and the urgent need to further explore and understand their environmental impact.

Augmenting the design of a nozzle used in abrasive jet machining process with computational fluid dynamics

The nozzle is an important part that affects the performance of the abrasive jet machining. It is a micromachining process, where the target material is being eroded by the effect of a high-speed continuous flow of abrasive particles, which are move out from a nozzle. A nozzle is required to carry out the particles to remove the material with the help of a large velocity of the microjet. The common nozzle shape presently used in this process is a rectangle and circular shape, which gives a low flow rate and further demands to reduce the material removal rate (MRR). In this work, three different geometrical types of nozzles: (i) convergent nozzle (25 mm) length, (ii) convergent nozzle (50 mm) length, (iii) modified convergent nozzle has been designed. The simulations of the flow have been analyzed using computational fluid dynamics. The velocity and pressure of the particles inside the nozzle were compared. The results show the improvements in the modified convergent nozzle are about 42.84 m/s of velocity and the pressure inside the nozzle tip is about 994424.5 Pa. Due to the swirl flow in a modified convergent nozzle, the high material removal rate is achieved.

Additive manufacturing of LMD nozzles for multi-material processing

Additive manufacturing of metals has become a leading technology for function-integrated and individualized components. Ongoing research leverages this technology from single-material parts to gradient compositions and multi-material combinations. Powder-based laser metal deposition is the preferred process for these novel applications because of the ability to add onto freeform surfaces and flexible material use. A crucial aspect of this powder-based process is material loss due to overspray. Furthermore, the shape and size of the powder stream must be altered depending on the intended use. For example, thin walls and fine details require a narrow powder focus whereas a larger focus can accelerate the manufacturing of volumes substantially. To address this challenge, novel 3D printable and replaceable nozzles are developed. Compared to common nozzle designs, this new approach enables quick changing of different sized nozzles and incorporates additively manufactured flow paths. Finally, the stream quality is visualized by Schlieren photography.

Effect of novel built-in rotator on the performance of pleated cartridge filter

Large quantities of PM (particulate matter) produced in the construction process poses hazard for both the workers' health and the whole environment. Despite the wide application of cartridge filters to PM collection, incomplete cleaning often occurs during pulse-jet cleaning of common nozzles. In this study, a built-in rotator used in a larger-diameter pleated filter cartridge was developed to improve the effect of pulse-jet cleaning. Then, the pulse-jet cleaning performances between the built-in rotator and the common nozzle were compared. The results show that the pressure drop of the built-in rotator is similar to that of the non-built-in one under the same superficial filtration velocity. The number of rotations grows with the increase of high-pressure air, while it first increases and then remains stable with the sustained pulse time. For the common nozzle, the cleaning effect is influenced by the nozzle diameter and the jet distance. The optimum jet distance declines with the increase of nozzle diameter. Compared with the common nozzle, the pulse-jet cleaning frequency of the built-in rotator reduced from 11 to 9, the average pulse-jet cleaning interval extended from 4667s to 5402s, the average residual pressure drop decreased from 118.39Pa to 86.04Pa and the average pressure drop reduced from 243.01Pa to 232.52Pa. Despite the average peak dust emission concentration increased from 13.52mg/m3 to 14.34mg/m3, the average dust emission concentration decreased from 2.56mg/m3 to 2.51mg/m3. Therefore, it is proved that the built-in rotator can improve the performance of pleated cartridge filter.

On the Influence of the Slot Orifice in Diesel Common Rail Nozzle

Background:The paper deals with a diesel common rail nozzle in which a novel orifice layout is implemented.Objective:Its influence on the nozzle mechanical-hydraulic behavior and on the spray shape transient development is experimentally investigated.Methods:In the research, a solenoid injector for light duty diesel engines is equipped with the novel nozzle prototype and tested. The prototype layout is described, pointing out the features of the nozzle orifices, in which a Slot cross-section is adopted; the investigation is accomplished extending the hydraulic tests and the spray visualizations to a reference nozzle with standard holes. The influence of the hole layout on the mechanical-hydraulic behavior of the nozzle is assessed by experimental analysis based on the rate of injection measurement, in comparison with the reference nozzle. Once the hydraulic behavior of the novel nozzle has been characterized in terms of mass flow rate, the slot influence on the spray shape is assessed analyzing the macroscopic features such as the penetration distance and the spray angle, in non evaporative conditions. The study is carried out under transient injection conditions, for different injection pressures, up to 1400 bar.Results:The results on spray characteristics also provide reference information to set up spray models suited to take the Slot orifice into account.

Design and Analysis of Elliptical Nozzle in AJM Process using Computational Fluid Dynamics

Abrasive jet machining (AJM) is a micromachining process, where material is removed from the work piece by the erosion effect of a high speed stream of abrasive particles carried in a gas medium, which are emerging from a nozzle. Abrasive machining includes grinding super finishing honing, lapping polishing etc. The common nozzle shape presently used in AJM machining process is rectangle and circular shape nozzle which gives a low flow rate and further demands on decreasing the material removal rate (MRR), so this research mainly focuses on designing nozzle geometry to improve flow rate and MRR in AJM machining process. The elliptical shape nozzle has been designed and analyzed using computational fluid dynamics software (CFD). CFD is the most efficient software for flow rate analysis. The result shows the improvement in flow rate about 574.2m/sec and MRR of newly designed nozzle geometry i.e elliptical shape in abrasive jet machining.

A Comparison of an Unhooded and Hooded Sprayer for Pesticide Drift Reduction

Management of drift from pesticide applications is important for human and environmental health concerns. It is also necessary to ensure adequate dosage of the pesticide meets the target species(s). A variety of factors can affect the drift potential of a pesticide application, including nozzle selection, solution chemistry, and application equipment. In the present study, a comparison of two ground sprayers, one with a hood and one without a hood, is made using three common ground nozzles in the US. The hooded sprayer reduced the drift potential of the pesticide application for all nozzles tested. In addition, higher spray coverage under the boom was measured when using the hooded sprayer. The results of this study indicate that incorporating a hood will lead to reduced drift potential from a pesticide application.

Study of hydrodynamic characteristics of regular packing of the nozzle-shaped elements

The article presents the results of experimental investigations of the hydrodynamic characteristics of a regular packing of nozzle-shaped elements, the results of comparative analysis of different types of nozzles, showing that the studied nozzle has a more developed specific surface during hydraulic resistance comparable with the most common industrial nozzles.

Electromagnetic Super – Compressibility

The dynamic emitter-a nozzle with a disposed along its axis central conic body-is a new engineering decision. The phenomena arising during its work are valuable and prospective both in fundamental science and practical application. During our experiments with this device we have discovered spiral-twisted non-ideal plasma wave structures arising in subsonic and supersonic gas jets flowing from the nozzle with a central cone. We consider very important and prospective the fact that the flow from the dynamic emitter remains almost stable both in shape and power with the distance from the nozzle outlet increasing. For example, the air jet from the nozzle with a central cone can deflect a steel plate of weight 2.55 kg, pending on the 120 mm wire, for about 45 mm at the distance of 400 mm. At this distance the power of the flow from the common conic nozzle is insignificantly low. Also in our experiments we registered phase transitions of air, argon and nitrogen to liquid and solid in the jets at room conditions (temperature of the jet was 285 K, humidity about 5-7%), which is very unusual and provides a lot of practical opportunities. Water vapor flowing from the dynamic emitter creates the mentioned non-ideal plasma structures with increased density of electrons that provides concentration of energy in small volumes (in the nodes of the structure) and high energy radiation (in the experiments there were detected electromagnetic fields up to 1 GHz). The received results can be explained with introducing the concept of electromagnetic super-compressibility which has been the primary aim of our work.

An Experimental Study of the Nanoparticle Colloid Hydrodynamic Cavitation Jet Polishing Performance under Different Nozzle Designs

Nanoparticle colloid hydrodynamic cavitation jet polishing (HCJP) is a super-smooth machining technology. This technology utilizes the interface reaction to remove material from the workpiece and uses cavitation effect to improve the processing efficiency. In this paper, the prototype equipment of HCJP is researched. Based on the prototype equipment, the processing experiments of pulsed jet nozzle, swirling jet nozzle and common cone-shaped nozzle have been done and the results of the experiments are compared with each other. The experiment results indicate that the roughness of the surfaces polished by three nozzles has remarkably decreased. The material removal rate of pulsed jet nozzle is the highest among the three types of nozzles. The material removal rate of the swirling jet nozzle is not improved obviously compared with the common cone-shaped nozzle. The processing experiment of monocrystalline silicon by the pulsed jet nozzle has been done and the roughness of processed surface is Ra 0.475 nm.

Effect of Exit Spacing in a Multiple-Jet Nozzle on Noise Levels at Audible Frequencies

This work investigated the effect of exit spacing on audible noise levels generated by a multiple-jet nozzle, which replaces the single exit in a common nozzle with multiple smaller exits to reduce the risk of hearing damage. Sound measurements and 1/3-octave band analyses were performed for multiple-jet nozzles with varying exit diameters and exit spacings. Results show that the effect of exit spacing is evident below a certain frequency range, which falls in the relatively low frequency part of the sound spectrum. The frequency range affected by exit spacing was found to extend to higher frequencies if the exits were more closely distributed. It was found that decreasing the exit spacing will shift the sound spectrum toward the low frequency side, which has been shifted toward the high frequency side by the use of smaller exits, and will increase the sound pressure levels at lower frequencies. When the exits were confined in a limited area, to maintain a constant total exit area, decreasing the exit diameters will increase the number of exits and reduce the exit spacing. Smaller exit diameters will increase the sound frequency and shift the sound spectrum toward the high frequency side, while decreased exit spacing has the opposite effect of shifting the spectrum toward the low frequency side. Due to these two opposing effects, for a multiple-jet nozzle with a limited size, there is an optimum exit diameter that, depending on the method used to evaluate the overall sound pressure level, generates the lowest sound pressure levels in the audible frequency range. If there is no limit to its physical size, a multiple-jet nozzle should avoid using an exit spacing that is too small. The minimum exit spacing required to avoid the adverse effects of a small exit spacing requires more extensive studies.

Structural Design of Symmetric Laminated Ceramic Nozzle and Study on it’s Erosion Behavior

Al2O3+(W,Ti)C/Al2O3+TiC symmetric laminated ceramic materials and nozzles were produced by hot pressing in order to reduce the tensile stress at the entry and the exit region of nozzles and improve their erosion wear resistance.The test results show that both hardness and toughness of laminated ceramic materials are improved than the simple materials.Under same erosion conditions,the laminated ceramic nozzles have superior erosion wear resistance to that of the common ceramic nozzle;the experimental value of optimal layer thickness ratio is 2.In addition,the residual thermal stress generated in the preparation of laminated ceramic materials is analyzed by finite element method(FEM).Relationship between stress distribution and layer thickness ratio is obtained.It is suggested that the residual thermal stress lead to grain refining mechanical properties strengthening,and improve the erosion wear resistance of laminated ceramic nozzles improving.The theoretical value of optimal layer thickness ratio is 2,the experimental results are consistent with the theoretical prediction.