Nozzle Axis Research Articles

Effect of the Mixing Structure Parameters of a Self-reflux Burner on Combustion Characteristics and NOx Emission

To solve the problem of low efficiency of NOx emission reduction in self-reflux burners, this study is based on the concept of coordinated control of self-reflux burner structural and thermal parameters. After completing the structural design and optimization of thermal parameters, we continue to adjust the two key structural parameters: the nozzle axis distance and the length of the cylindrical section, to minimize NOx emissions. These are the two parameters that chiefly affect the mixing of flue gas and fuel gas. The results show that increasing nozzle axis distance can delay the mixing of gas and air and create a more uniform oxygen concentration field for the combustion process. The maximum combustion temperature is reduced from 1973.65 K to 1935.88 K and the volume fraction of NOx in the flue gas is reduced from 188.08×10−6 to 143.47×10−6. However, compared with the nozzle axis distance, the length of the cylindrical section of the burner has little effect on the mixing of the flow field. Under different cylindrical section lengths, the maximum combustion temperature does not change more than 3 K, and the volume fraction of NOx in the flue gas changes within 5×10−6.

Pitot probe response for pulsed supersonic gas flow characterization in beam profile monitor.

For beam profile measurement of high-intensity proton beams in the low-energy high-intensity proton accelerator at Bhabha Atomic Research Centre, a recent noninvasive technique based on gas sheets will be explored. The gas sheet for this instrument needs to be characterized for calibration and fine tuning of the sheet properties to provide better profile measurements. Pulsed sheet generators for similar applications have been characterized using movable vacuum chambers with a small slit and a gauge mounted inside. Pitot probes are more compact instruments and have been used to measure gas jet profiles in molecular beam applications where the jet was not pulsed. The performance of Pitot probes in the measurement of pulsed supersonic gas flow in vacuum was, therefore, investigated in this work. A test system was developed to generate a pulsed supersonic gas jet in vacuum, and a Pitot probe was inserted into the flow at various axial locations with respect to the nozzle. Measurements taken along the nozzle axis using this probe, as well as the axial Mach number and impact pressure computed using computational fluid dynamics and direct simulation Monte Carlo algorithms, were compared with fitting formulas. Schlieren images of the jet with and without the Pitot tube were also taken under different vacuum conditions.

Визначення режимів струменевої обробки криволінійних поверхонь виробів

Aim. Developing an approach for determining the modes of jet treatment for the curved surfaces of products to ensure uniform processing, which is achieved by maintaining a constant distance from the nozzle end to the surface and maintaining the perpendicularity of the nozzle axis to the curved surface at the point of processing during movement and changing the nozzle inclination. Method. The basic principles of analytical geometry on the plane are used to describe the processed curved surface. Kinematic equations of a material point motion as the basic principles of theoretical mechanics were used to research the motion of the processed curved surface. Graphical dependences and analysis of the obtained results were carried out by using the mathematical editor. Results. The result is the complex of the mathematical models, the use of which in control systems of technological equipment will ensure uniform processing by adjusting the linear velocity of the product surface and the angular velocity of the jet nozzle, and thus ensure the required accuracy and quality of products. Scientific novelty. The approach for modeling jet treatment of products with curved surfaces is improved, namely the method of determining processing modes under conditions of constant distance from the nozzle end to the surface and perpendicularity of the nozzle axis to the tangent at the processing point is proposed. Analytically, expressions for mathematical description of curved surfaces depending on their shape and character of motion are obtained. Practical significance. The proposed approach is recommended to be used in technological processes of jet treating for the products of complex configuration, when designing units of technological equipment or devices designed to ensure the movement of the product or the tool. Mathematical models can be the basis for ensuring the quality of curved surfaces of products obtained by jet treating.

Fundamental study on reduction of dross in fiber laser cutting of steel by shifting nozzle axis

In the fiber laser cutting of steel with nitrogen assist gas, the effect of positional relationship between the centers of a nozzle and a laser beam on the cutting quality was investigated by laser cutting experiments and computational fluid dynamics analysis of the assist gas flow. The laser cutting experiment of 3.2 mm cold rolled steel was carried out by a 3 kW fiber laser. The spot diameter of the laser beam and the inner diameter of the nozzle were 140 μm and 2.0 mm, respectively. In laser cutting, by shifting the center of the laser beam toward the cutting direction inside the nozzle, the dross height becomes large. In the nozzle shifting setup, the cooling effect becomes high due to a large inflow of assist gas into the kerf, and the reduction of assist gas pressure results in the control of the cooling effect. The formation of appropriate kerf shape by changing the focusing position inside the workpiece leads to an appropriate flow field of assist gas in the kerf. As a result, similar dross height could be obtained by the nozzle shifting setup, compared with that by the coaxial setting of the nozzle and laser beam. The nozzle shifting setup can perform the equivalent dross height to the coaxial setting of the laser beam and nozzle even at lower pressure of the assist gas, and the reduction of assist gas consumption is possible at the same level of dross height in fiber laser cutting of steel.

Influence of Nozzle Geometry on Fluid Flow Parameters

The article discusses ways for optimization of a standard nozzle cup design to achieve a narrower paint flow. The analysis of a standard nozzle cup shows that distribution of air pressure is critically uneven both along the nozzle axis and in the radial direction. A decrease in pressure is about <i>45</i>% at the distance of <i>2 mm</i> from the front surface of the nozzle cup. Air pressure decreases about <i>40</i>% at the distance of <i>2 mm</i> from the nozzle axis in the radial direction. Air velocity decreases about <i>52</i>% at the distance of <i>4 mm</i> from nozzle surface but then the velocity stabilizes and decreases is about <i>59</i>% at the distance of <i>10 mm</i> from the nozzle surface in comparison to its magnitude on the nozzle surface. Six extra holes and a circular rim were added to the standard nozzle cup to obtain paint stream as narrow as possible. Also was modified inner surface of the nuzzle cup. Totally, four different components were analysed. The results show that with increasing the nozzle cone by fifteen or more degrees, the pressure distribution decreases. Most optimal solution has six small holes around the nozzle hole and a small rim covering all holes. In this case, pressure decreases only <i>3</i>% in the axial direction and <i>4</i>% in the radial direction at the distance of <i>2 mm</i> from the front surface of the nozzle. Distribution of air velocity is still significant but its magnitude is about <i>35</i>% … <i>45</i>% less than at the standard nozzle cup.

Experimental characterization of nozzle flow expansions of siloxane MM for ORC turbines applications

This paper reports extensive experimental results characterizing the supersonic expansion of organic vapor MM (hexamethyldisiloxane, C6H18OSi2) in conditions representative of actual Organic Rankine Cycle turbine operation, in the close proximity of the liquid-vapor saturation curve. Experiments were conducted on the Test Rig for Organic VApors, at the Laboratory of Compressible fluid dynamics for Renewable Energy Applications of Politecnico di Milano. A planar nozzle featuring a design exit Mach number of 1.6 was characterized by measuring total pressure, total temperature, static pressures along the nozzle axis and by schlieren visualizations. The non-ideal influence of inlet total conditions on nozzle expansions was verified by gathering data exhibiting total compressibility factor ZT ranging from 0.39 (strongly non-ideal) to 0.98 (almost ideal conditions). Pressure ratio measured at the lowest ZT exceeded by 10%–20% the one at highest ZT along the whole nozzle. An extensive experimental dataset was analyzed to assess the influence of both total compressibility factor ZT and total fundamental derivative of gasdynamics ΓT on the non-dimensional pressure distribution along the nozzle axis. It was investigated whether one parameter only can univocally identify a non-dimensional nozzle expansion. Significant validation data for simulation codes and design tools are provided for MM and for siloxanes in general.

Morphological/alignment properties of thermoplastic polyurethane nanofiber affected by processing parameters

Thermoplastic polyurethane (TPU) in nanofiber or submicron fiber has widespread application areas including the biomedical applications, such as artificial vein, cell cultivation etc. due to both TPU’s and nanofiber’s morphological properties. The morphology and aligment of nanofibers obtained from electrospinning are significantly affected by process parameters, which affect their end uses. This study aims to investigate the effect of process parameters of electrospinning (nozzle axis type, collector type, collector speed and filler types) on morphological properties (fiber orientation, fiber diameter and porous structure) of thermoplastic polyurethanes. Experimental results showed that nanofiber diameter increased with an increase of collector speed due to the relaxation of extensible TPU nanofiber after spinning process. When the rotational speed of collector reaches to 2000 rpm, the orientation could be observed. Using rotational wire collector resulted in thinner and more oriented fibers compared to rotating cylinder collector. Adding salt particles results in thinnest and highly oriented nanofiber webs. Higly porous surfaces were obtained using coaxial technique at the same feeding rates with miscible solvents for both shell and core. It was seen that using solvent with low boiling point in core may lead to higher porous surfaces. Nanofiber diameter increased using coaxial nozzle instead of single axis nozzle.

Additive manufacturing via tube extrusion (AMTEx)

Large scale Fused Filament Fabrication (FFF) is a growing area of interest within AM, with several unresolved problems: the volumetric cost of materials is high, the printing process is slow and low cooling rates result in unstable or sagging structures. This paper presents the concept of additive manufacturing via tube extrusion (AMTEx) as a means of overcoming these issues. Using hollow tubes in place of solid extrusions means material use is reduced and cooling properties are vastly improved, allowing spans in excess of 400 mm without sag. Conventional freeform extrusion relies on the use of six-axis robots to orientate the extruder nozzle tangentially to the toolpath. It was found that slight pressurisation of the inside of printed tubes allowed extrusion at more than 90° from the nozzle axis without tube collapse. Aside from reducing the possibility of robot-print collisions, this also allows the use of traditional 3D printing slicing software to generate printer toolpaths. It also opens the potential to use conventional three-axis machines, greatly increasing the applicability of printing with tubes. AMTEx tubes were found to be stronger under tension and bending compared to equivalent FFF parts and had significantly improved ductility.

Gasdynamic and Acoustic Characteristics of a Subsonic Jet-Edge Rod Generator of Acoustic Radiation

The design of a subsonic jet-edge rod generator of the Hartmann-type oscillator and a scheme of measuring its acoustic parameters are presented. In this generator, unlike the Hartmann oscillator, not a cylindrical gas jet but an annular gas jet, moving along the thin cylindrical rod positioned at the axis of the generator nozzle, is used. A parametric investigation of the gasdynamic and acoustic processes arising in the tubular cavity of such a generator as a result of the interaction of a subsonic gas jet with this cavity has been performed with consideration for the nonstationary structure of the gas flow in the generator cavity. Recommendations on the choice of the design of a jet-edge rod generator of acoustic radiation with regard for its practical application are given.

Automatic detection of oblique shocks and simple waves in schlieren images of two-dimensional supersonic steady flows

This paper presents a technique to automatically detect flow structures recorded in schlieren images of supersonic flows. The method provides position and local slope of the detected lines. Salient flow structures considered are shock waves, expansion fans and Mach waves. If the local flow direction is known, the technique provides local Mach number measurement. Moreover, the peculiarities of schlieren technique make the algorithm suitable for Mach measurements in flows where direct velocity measurements are challenged by difficult insemination and for which calibrated aerodynamic pressure probes are not available. The technique is applied to two test cases. In the first case study, the local Mach number is measured at the axis of a supersonic nozzle operated with siloxane vapor MDM. In the second test case, supersonic flow of MDM was analyzed around a diamond shaped airfoil providing the Mach number upstream/downstream oblique shocks/expansion fans and the slope of oblique shocks/fan edges.

Cavitation-abrasive wear working collectors of pumps

The main results of the study of hydraulic losses in the suction line and mechanical damages of the impellers of pumps due to cavitation-abrasive wear are given in the article. The scientific task of using theoretical bases for justifying factors affecting the wear rate of pump parts is being solved. On the basis of these theories, a technique is proposed for calculating the wear rate of the elements of the flow-through part of the pumps. During the experimental studies, standard methods of laboratory-bench testing of pumps were used. The operating modes of pumps with minimal wear of their parts are established. Poor hydraulic flow conditions with swirl zones cause an increase in energy losses and a redistribution of flow rates across sections. Wear the parts that are flowing directly proportional to the concentration in the sediment flow, the cube of the flow velocity, the time of action on the pump units. The presence of unsteady vortex regions, especially when the effect of eddy formation increases, leads to fluctuations in the velocities and pulsations of the flow pressure. Cavitation in the pump occurs when the operating modes of the pump differ from the nominal. The increase in volumetric efficiency, the improvement of hydraulic flow conditions to the pump impeller and the reduction of cavitation wear were achieved by the authors in a new pump design that contains guide planes fixed to the throttle plate parallel to the suction nozzle axis with an elastic outer surface. In the same areas of constructive improvement of pump assemblies, it is necessary to search for ways to reduce the negative impact of cavitation and hydroabrasive erosion on the life of pumps.

Numerical Analysis of the Particle-Induced Effect on Gas Flow in a Supersonic Powder-Laden Oxygen Jet

The article addresses the particle-induced effect on gas flow by a developed mathematical model simulating the supersonic oxygen–limestone powder mixture jet from a newly designed, freely swinging oxygen lance for dephosphorization in a converter. The model was validated first and then employed to analyze the gas flow dynamics with respect to the jet structure, pressure wave sequence and velocity distribution, and particle motion behaviors over a range of powder particle sizes and mass flowrates. Numerical results reveal that the powder causes significant changes of the oxygen jet structure and weakens the pressure wave sequence outside the nozzle despite the higher gas flow static pressure of the powder-laden oxygen jet than that of the single-phase oxygen jet there. Furthermore, the powder creates nonuniform radial distribution of the gas velocity as an “M-type” curve and greatly restricts the gas jet flowing along the nozzle axis, which results in the smaller gas flow velocity but slower velocity attenuation. These phenomena become increasingly remarkable as the powder particle size is decreased or the powder mass flowrate is increased. The particles are accelerated but the acceleration declines gradually along the nozzle axis. The greater powder mass flowrate or particle size induces the lower particle velocity.

The Formation and Evolution of Turbulent Swirling Vortex Rings Generated by Axial Swirlers

The present work investigates the formation process and early stage evolution of turbulent swirling vortex rings, by using planar Particle Image Velocimetry (PIV) and Large Eddy Simulation (LES). Vortex rings are produced in a piston-nozzle arrangement with swirl generated by 3D-printed axial swirlers in experiments. Idealised solid-body rotation is applied in LES to evaluate the effect of nozzle exit velocity profile in experiments. The Reynolds number (Re) based on the nozzle diameter D and the slug velocity U0 in the nozzle is 20,000. The swirl number S generated ranges from 0 (zero-swirl vortex ring) and 1.1, covering the two critical swirl numbers previously identified in a swirling jet. Both PIV and LES results show that the formation number F decreases linearly as S increases, with the maximum F ≈ 2.6 at S = 0 (produced by the swirler with straight vanes) and minimum F = 1.9 at S = 1.1. The corresponding maximum attainable circulation in the nozzle axis parallel plane also diminishes with increasing S. Evolution of compact rings produced by a stroke ratio L/D = 1.5 reveals that circulation decay rate is largely proportional to S. The trajectory of the vortex core in the axial direction, hence the ring axial propagation velocity, decreases as S, while that in the radial direction and the radial propagation velocity, increase with S. An empirical scaling function is proposed to scale these variables.

Visualization of features of atomizing circular liquid sheet using simultaneous Volume Laser-Induced Fluorescence

Present work is an experimental investigation of primary atomization of a radially expanding circular liquid sheet produced from a cylindrical vertical water jet issuing out from the convergent nozzle and impinging orthogonally on a horizontally placed cone-disc deflector below the nozzle. The radially expanding thin circular water sheet formed from the peripheral edge of deflector disc. The atomization process of expanding liquid sheet is captured simultaneously for the first time in the top and side views using a high-speed Volume Laser-Induced Fluorescent (VLIF). The experiments were conducted at 6 kHz framing rate for various jet Weber numbers (Wejet) over a range of 996 <Wejet < 7480. The top view VLIF revealed interesting spatiotemporal features of atomizing sheet such as outer edge thickness, liquid threads, ligaments and droplets and formation of perforations punctures (perforations) on the local sites of liquid sheet. Moreover, the evolution of the perforations leading to the breakup into ligaments and droplets was also captured in top view VLIF as well. Results show the liquid sheet outer edge (rim) thickness is unaffected by change in Wejet, whereas the rim velocity is found linearly increases with increase in Wejet. The liquid threads observed at the rim are subjected to end-pinching effect (as Ohnesorge number, Oh ≪ 1) when detached (because of Plateau-Rayleigh instability) from the rim. Ligament size in terms of length (Llig) and thickness (tlig) are measured at two different locations; (i) at rim (~100 mm from nozzle axis) and (ii) at about 130 mm downstream from the rim. Ligaments measured at downstream of the rim were found to be smaller than those measured at the rim. Further downstream, the droplets are formed whose size decreased with increase in jet Weber number (Wejet). Three different sites of origin of droplets namely rim, perforations edges and liquid bridge are identified. The variation of droplet diameter that produced from the rim with the Wejet is found to follow D10~Wejet-1/4 and D32~Wejet-1/5. Various features originating from the perforations are captured in top view VLIF and quantified for the first time using rigorous image processing methods. These features are perforation diameter, perforation’s front and rear edge thicknesses and velocities, liquid bridge, droplets from perforation via ligaments and via formation of liquid bridges. The perforations are formed close to sheet breakup and number of occurrence of perforations increases with increase in Wejet. The rear edge of perforation is seen thicker than the front edge because of larger accumulation of water in the rear edge. Consequently, the rear edge velocity is seen lower than the front edge velocity during the life span of perforations from the origin to their rupture into ligaments and droplets. Liquid bridge formed by merging/coalescing of two perforations is also observed. It is found that liquid bridge thickness increased with increase in Wejet. The droplets originating from the perforations are weak function of Wejet.

Effect of the fuel-air flow velocity on heat release rate of swirling non-premixed methane flames

A laboratory-scale gas turbine model combustor fueled with methane is studied experimentally with the aid of three-dimensional computed tomography of chemiluminescence (3D-CTC) and high speed (5 kHz) chemiluminescence imaging. Various fuel-lean operating conditions were tested to investigate the impact of flow velocity on heat release rate oscillation and spatial structure transition with fixed global equivalence ratio of about 0.65 and dump plane velocity of 2.9–18.3 m/s. In the study of combustion structure transition, the three-dimensional relative emissions of CH* were measured and taken as qualitative indicators of the heat release rate. This 3D measurement method utilizes CH* images from 8 directional as inputs combined with tomographic algorithms to compute the 3D distribution of CH* CL intensities. For all tested conditions, pronounced extension of inner recirculation zone (IRZ) along the nozzle is observed under the attached (V-shaped) swirl stabilized flames. During the increase of Reynolds number, the heat release zone changing obviously along the nozzle radial and axis direction, and the largest heat release plane moves downstream significantly. In addition, an intensified high-speed camera was adopted for the heat release dynamics study. Strong oscillations appeared in the flame zone that significantly affected the total heat release oscillations, and oscillation increases with the raise of Reynolds number.

РОЗРАХУНОК ТЕМПЕРАТУРНО-ШВИДКІСНИХ ПАРАМЕТРІВ ЧАСТИНОК ПРИ ХОЛОДНОМУ ГАЗОДИНАМІЧНОМУ НАПИЛЮВАННІ

The method of computational fluid dynamics (CFD) for the supersonic nozzle SK-20 of the low-pressure cold gas-dynamic spraying equipment DYMET-405 was applied for calculation of particles impact temperature and velocity. The application of the CFD method is the one-dimensional isentropic gas-dynamic model considers the flow only along the nozzle axis, without taking into account the heat exchange with the nozzle and the friction losses on the internal walls, which leads to obtaining overestimated results of calculations. Previously it was found out that the difference in the values obtained by numerical simulation and the results of calculations of a one-dimensional isentropic model was less than 10%. Numerical simulation of the two-phase flow of the cold spray process has been performed using the Ansys Fluent Academic software package. The influence of the initial cold spray process parameters such as temperature and pressure at the nozzle inlet on the change in temperature and velocity of aluminum particles with a diameter of 25 μm at the moment of impact with the substrate has been studied. Also, the influence of the particle size on the above-mentioned parameters has been obtained. The numerical simulation results of the particle impact temperature with the substrate have been used to calculate the critical velocity of aluminum powder – the velocity needed for coating formation. It is known that the formation of cold spray coatings depends on the velocity of the powder particles. For each material, there is a critical velocity at which the process of forming the coating begins. At particle velocities above the critical one, their adhesion to the substrate and the formation of the coating, due to the plastic deformation of the particles, occurs, while at lower velocities the surface erosion or deposition with low efficiency under certain conditions is observed. As a result of simulation and calculations of the critical velocity, the window of spraying was developed, that is the region of values of velocities and temperatures of the particles of aluminum powder, depending on the temperature and pressure of the air at the nozzle inlet, at which the formation of coatings is possible.

Simulation of nozzle position optimization based on single-phase flow

The numerical simulation on the lubrication of the complex gearbox was studied and an optimization for its injection lubrication system was carried out. Firstly, a pair of high speed gear test bench was built and related experiments were completed. The experimental results verified the correctness of the numerical simulation modeling method. Then the numerical model of the injection lubrication of the complex gear box was established, the simulation analysis was carried out. The results show that the overlong injection distance, the angle of the end face and the arrangement of the nozzle in the out of mesh side are not good for lubrication. And there is a trace in the center plane of the two meshing gear, along which the ejected oil will be under the least impact of the high speed airflow that driven by the rotating gears. When the nozzle axis is in the direction of the trace, the gear lubrication condition is the best.

Geometry and Motion Characteristics of Bubbles Released in Liquid Cross Flow

To investigate the characteristics of the bubbles trapped in liquid cross flow, air was injected into flowing water circulated in a closed loop. High speed photography was used to record bubble images instantaneously. An image-processing code was specifically developed to identify bubbles in the images and to calculate bubble parameters. Effects of the water velocity and the flow rate of the injected air on bubble patterns were investigated. The results indicate that the inclination of bubble trajectory relative to the nozzle axis is enhanced as the water velocity rises. Meanwhile, bubble size varies inversely with the water velocity. The bubble profile tends to be rounded as the water velocity increases. Fluctuations of the bubble velocity are intensified as the water velocity decreases. As the balance between the external forces exerted on the bubble is reached, an approximately linear relationship between the velocities of the bubble and the water is manifested. For a given equivalent bubble diameter, the bubble terminal velocity is higher than that associated with quiescent water. At small Eötvös number, the consistency of the bubble aspect ratio in the liquid flow and quiescent water is revealed. The range of Eötvös number is extended considerably due to the flowing water. Values of Weber number are accumulated in a range within which high bubble aspect ratio is associated with relatively high water velocity.

Numerical investigation on the interfacial characteristics of steam jet condensation in subcooled water flow in a restricted channel

As a kind of direct contact condensation, steam jet condensation in subcooled water flow is very common in various industrial applications. Particle model has been employed to investigate the interfacial characteristics of the steam jet condensation in subcooled water flow in a restricted channel, in which a thermal phase change model was inserted into ANSYS CFX as CFX Expression Language (CEL) to simulate the interphase heat and mass transfer process. To validate the model correctness, the steam plume and temperature profiles were compared with the experimental data. The interfacial characteristics including the variation of steam-water interface, local heat transfer coefficient and local condensation rate have been discussed under different operating conditions. Based on the dynamic equilibrium of steam supply and its condensation by the ambient water flow, the steam plume variation was analyzed. The axial profiles of thermodynamic parameters along the nozzle axis were studied with the theory of expansion and compression waves to reveal the formulation mechanism of ellipsoidal steam plume. Then the supersonic flow was observed at some distances from the straight nozzle exit in the numerical results as the related experimental results indicated. The numerical results show that steam plume expands with steam mass flux and water temperature increasing, while it contracts with the increase of water Reynolds number. With the increase of water inlet temperature, the local condensation rate decreases. As the Reynolds number of water flow increases, the local heat transfer coefficient increases and the local condensation rate increases as well.

Numerical simulation of aerodynamic focusing of particles in supersonic micronozzles

Particle-laden flows in plane, axisymmetric and 3D supersonic micronozzles are investigated numerically using a one-way coupled Eulerian/Lagrangian approach. The carrier gas flow is calculated by solving the Navier–Stokes equations. Rarefaction effects are taken into account by imposing the velocity slip and temperature jump boundary conditions on the nozzle walls. The parameters of the flow around particles are varied in a wide range including hydrodynamic, transitional and free-molecular regimes. It is shown that a collimated beam of particles can be produced using the effect of aerodynamic focusing due to converging flow streamlines in the subsonic part of the nozzle. The collimation is preserved in the supersonic part where the flow is divergent because the rapid drop in the gas density decreases significantly the force acting on the particle. An interesting and unexpected feature of aerodynamic focusing is that the beam collimation is observed in two different ranges of particle sizes. In the first range, for relatively large particles, the collimated beam consists only of particles seeded close to the nozzle axis. In the second range, for smaller particles, the beam includes also a great portion of peripheral particles. The numerical simulation also shows that aerodynamic focusing in a supersonic, convergent-divergent, nozzle enables one to increase significantly the velocity of the collimated beams compared to previously reported results for convergent subsonic nozzles. It may be helpful for technological applications where the aerodynamic scheme of particle focusing can be used (microthrusters, needle-free drug injection, microfabrication, etc.).