Nozzle Unit Research Articles

Microgel-in-Microgel Biopolymer Delivery Systems: Controlled Digestion of Encapsulated Lipid Droplets under Simulated Gastrointestinal Conditions.

Structural design principles are increasingly being used to develop colloidal delivery systems for bioactive agents. In this study, oil droplets were encapsulated within microgel-in-microgel systems. Initially, a nanoemulsion was formed that contained small whey protein-coated oil droplets ( d43 = 211 nm). These oil droplets were then loaded into either carrageenan-in-alginate (O/MC/MA) or alginate-in-carrageenan (O/MA/MC) microgels. A vibrating nozzle encapsulation unit was used to form the smaller inner microgels ( d43 = 170-324 μm), while a hand-held syringe was used to form the larger outer microgels ( d43 = 2200-3400 μm). Calcium alginate microgels (O/MA) were more stable to simulated gastrointestinal tract (GIT) conditions than potassium carrageenan microgels (O/MC), which was attributed to the stronger cross-links formed by divalent calcium ions than the monovalent potassium ions. As a result, the microgel-in-microgel systems had different gastrointestinal fates depending upon the nature of the external microgel phase; i.e., the O/MC/MA system was more resistant to rupture than the O/MA/MC system. The rate of lipid digestion under simulated small intestine conditions decreased in the following order: free oil droplets > O/MC > O/MA > O/MA/MC > O/MC/MA. This effect was attributed to differences in the integrity and dimensions of the microgels in the small intestine, because a hydrogel network surrounding the oil droplets inhibits lipid hydrolysis by lipase. The structured microgels developed in this study may have interesting applications for the protection or controlled release of bioactive agents.

Needleless electrospray of magnetic film from magnetization-induced cone array

ABSTRACTElectrospray is a simple and versatile approach to deposit thin-films. Traditionally, electrospray is achieved through capillary nozzle electrode to create fluid jet. Here, we report a novel needleless electrospray approach to continuously deposit the magnetic film from the magnetization-induced self-assembling cone array of poly(vinyl pyrrolidone) (PVP)/Fe3O4 ferrofluid without any nozzle and feed unit. A spiral tower is used to pump the PVP/Fe3O4 ferrofluid and a 3D peak-cluster is self-assembled on the tip surface under an external magnetic field. The multiple and parallel jets can be continuously emitted from the cone array of 3D peak-cluster, and get deposited on the aluminum foil as a smooth magnetic film when a high-voltage electric field is further applied. This needleless electrospray approach is simple, and cost-effective with a high productivity. The prepared magnetic film mainly composed of Fe3O4 nanoparticles and PVP polymer exhibits superparamagnetic property and good magnetic field responsive property.

Flow of Combustion Products Containing Condensed-Phase Particles over a Recessed Vectorable Jet Nozzle

The flow of combustion products containing condensed-phase particles over the recessed vectorable nozzle of a solid-propellant rocket motor was investigated with the use of the Reynolds-averaged Navier–Stokes equations, equations of the k–e model of turbulence, and the Lagrange approach. The fields of flows of combustion products and the mechanical trajectories of condensed-phase particles in the charge channel, the prenozzle space, and the nozzle unit of this motor were calculated for different angles of swing of the nozzle. The formation of vortices in the gas flow in the neighborhood of the downstream cover of the nozzle and their influence on the movement of particles different in size were considered.

Formation of Vortex Structures in the Prenozzle Space of an Engine with a Vectorable Thrust Nozzle

A numerical simulation of the hydrodynamic effects arising in the process of work of the vectorable thrust nozzle of a solid-propellant rocket engine has been performed. The fields of the flows of combustion products in the channel of a charge, the prenozzle space, and the nozzle unit were calculated for different angles of vectoring of the nozzle. The distributions of the gasdynamic parameters of the flow of combustion products in the prenozzle space, corresponding to their efflux from the cylindrical and star-shaped channels of charges, were compared. The formation of a vortex flow in the neighborhood of the back cover of the nozzle was considered.

Fluid Flow Characteristics in Micro-Pump with the Aid of Peltier Devices and Thermal Expansion Material

Experimental study is performed to design and develop a cylindrical micro-pump driven by expansion and contraction of the heat deformation material, whose variation is caused with the aid of heating and cooling properties of Peltier devices. The pump consists of the diffuser valve unit, the heat deformation material unit, the nozzle valve unit, the Peltier devices and the cover. The input current of the Peltier devices is controlled by the bipolar power supply so that the Peltier devices are heated and cooled periodically. The working fluid flow in the micro-pump is caused by the periodical thermal deformation of material which is caused by the periodical heating and cooling of the Peltier devices. In order to measure the fluid flow in the micro-pump, micro air bubbles are employed as a tracer. The corresponding movement is recorded by X-ray apparatus and its velocity is measured by PIV (particle image velocimetry). It is found that, the micro-pump developed here can make the working fluid flow. The corresponding fluid flow in the micro pump is confirmed by the numerical method.

Engineering design and experimental research of non-metallic parts and components of the hot section of the advanced gas turbine engine

Technological and experimental research in support of creation of a high-temperature turbine nozzle unit made of diamond dust dispersion-hardened silicon carbide and the flame tube of a high-temperature combustion chamber made of carbon-fiber-reinforced-ray of ceramic composite material based on a ceramic polymer has been conducted. The studies demonstrated: • technological capability of creating a composite structure of the nozzle made of super-hard diamond dust dispersion-hardened silicon carbide compatible with the mating metal turbine units; • the results of testing the non-cooled flame tube made of carbon-fiber reinforced ceramic composite material based on a ceramic polymer. The results will be used in the design, manufacture and tests of non-metallic components of combustion chambers and turbines of auxiliary power units, small-sized gas turbine engines and helicopter engines.

Numerical simulation of heat and mass transfer processes in the nozzle and expansion unit of the separator–steam-generator system in waste-heat utilization complex

Homogeneous equilibrium and nonequilibrium (relaxation) models are used to simulate flash boiling flows in nozzles. The simulation were performed using the author’s CFD-code ANES. Existing experimental data are used to test the realized mathematical model and the modified algorithms of ANES CFD-code. The results of test calculations are presented, together with data obtained for the nozzle and expansion unit of the steam generator and separator in the waste-heat system at ZAO NPVP Turbokon. The SIMPLE algorithm may be used for the transonic and supersonic flashing liquid flow. The relaxation model yields better agreement with experimental data regarding the distribution of void fraction along the nozzle axis. For the given class of flow, the difference between one- and two-dimensional models is slight.

A Retrofit Variable-Rate Control System for Pressurized Slurry Tankers

<abstract> <b><i>Abstract. </i></b> In the last several decades, livestock effluent management practices and field slurry spreading operations have received increasing attention due to their economic and environmental implications. In this study, a variable-rate control system for pressurized slurry tankers was developed according a retrofit approach (i.e., as a self-standing module that can be adapted and mounted on existing slurry tanker equipment). The system provides farmers with a useful tool for achieving compliance with environmental protection regulations and for developing good practices for livestock and nitrogen management. This system is suitable for new and used pressurized tanker equipment. For field-testing purposes, this system was mounted on a double-axis 10 m³ slurry tanker equipped with a crawling nozzle distribution unit. Field experiments were conducted at two typical forward speeds (2 and 3 km h^-1) and three different nitrogen application rates (170, 250, and 340 kg ha^-1). Based on the experimental results, the system was generally capable of limiting the differences between the nominal and measured application rates to less than 9%. In addition, the data analysis indicated that the slurry spreading was not significantly affected by the forward speed of the tanker. The uniformity of nitrogen spreading was evaluated according to the UNI EN 13406:2002 standard. The results showed that the transverse field distribution was uniform throughout the working width of the machine and at all tested operating conditions, with maximum deviations that were limited to less than 15%.

ДОСЛІДЖЕННЯ ХАРАКТЕРИСТИК ТЕПЛОМАСООБМІННОЇ ПОВЕРХНІ НАСАДКОВИХ КОЛОН, ПЕРСПЕКТИВНИХ ДЛЯ ЗБАГАЧЕННЯ НЕОНОГЕЛІЄВОЇ СУМІШІ

One of the main factors determining nozzle rectifying columns operation is the mass exchange surface. The presented researches focus on the choice of nozzle design unit for neon helium mixture primary enrichment. Created universal experimental setup for studying the processes of rectification allows obtaining the basic characteristics of four nozzles: spiral, spiral-prismatic and two types of mesh saddle (10´10´0,2 mm and 12´12´0,4 mm). From the studied nozzles according to known requirements and taking into consideration a large-scale factor the best mesh saddle nozzle from a wire with a diameter 0,2 mm and the sizes 10×10 mm was chosen. This type of nozzle has low resistance of the irrigated nozzle (48 Pa) that is critical for the studied steam speeds (0,3 … 0,5 m/s).

Engineering design and experimental research of non-metallic parts and components of the hot section of the advanced gas turbine engine

Technological and experimental research in support of creation of a high-temperature turbine nozzle unit made of diamond dust dispersion-hardened silicon carbide and the flame tube of a high-temperature combustion chamber made of carbon-fiber-reinforced-ray of ceramic composite material based on a ceramic polymer has been conducted. The studies demonstrated: • technological capability of creating a composite structure of the nozzle made of super-hard diamond dust dispersion-hardened silicon carbide compatible with the mating metal turbine units; • the results of testing the non-cooled flame tube made of carbon-fiber reinforced ceramic composite material based on a ceramic polymer. The results will be used in the design, manufacture and tests of non-metallic components of combustion chambers and turbines of auxiliary power units, small-sized gas turbine engines and helicopter engines.

The microscopic features of cavitation erosion and the solution in the plastic injection moulding machines

The premature failure mode of the nozzle unit in the plastic injection moulding machines was discovered to be cavitation erosion, rather than corrosion. The microscopic features of the cavitation erosion on the soft aluminium alloy have its own distinct characteristics. Three types of erosion pits in different size order have been discovered: a large round pit with very smooth surface are in the size range of 1–2mm, small round overlapping pits in the pattern of parallel line are approximately 100μm, and micro erosion pits are about 5μm. These different size order erosion pits might be associated with the different size order of bubbles imploding. The root cause of the bubble formation was the alteration in surface tension and the vapour pressures due to the dosing chemicals in the coolant. The solution to the cavitation erosion with substituting stainless steel to aluminium alloy has been successful.

Numerical investigation of the flow of ultradisperse particles of the aluminum oxide in the solid-fuel rocket engine nozzle

The work deals with the two-phase flow investigation. The computations were done for a continuous coagulation model within the framework of the phenomenological multi-fluid model of the medium. A conclusion was drawn that the diminution of the particles size leads to a reduction of two-phase losses in the nozzle unit of the solid-fuel engine.

Simulation of a nonstationary flow in a channel with a distributed blow from the channel walls and forced pressure oscillations

UDC 532.529 A nonstationary flow in a channel with a blow was simulated on the basis of the Reynolds-averaged Navier- Stokes equations and the two-parameter k-e model of turbulence. The pressure near the left end of the chan- nel changes by the harmonic law. It was established that the k-e model of turbulence can be used for calculating the nonstationary flows formed in the indicated channel by a blow. Introduction. The oscillations of the parameters of a working substance in the combustion chamber of a solid-propellant engine (SPE) represent a dangerous effect that can disturb the normal working conditions of the en- gine and, in some cases, cause its failure. These oscillations are due to the vibrating combustion or the hydrodynamic instability of the flow of the fuel combustion products. A model of a fluid flow in a channel with permeable walls can be used for simulation of a flow of combus- tion products in the channel of an SPE charge because this model reflects the significant process of transfer of a solid fuel from the burning surface of the charge. However, in the indicated model, the decomposition and combustion of the fuel in the thin near-surface layer of the charge are not taken into account. The inner flow of a working substance in the channel of an SPE is turbulent, and complex physical processes proceed in the working space of the SPE against the background of its general gasdynamic state. The turbulence of the gas flow in the indicated channel influences its characteristics and intensifies the heat transfer at the surfaces of the prenozzle space and the nozzle unit of the SPE. The nonstationarity of this gas flow can be caused, e.g., by a change in the rate of gas blow along the generatrix of the channel or by the forced oscillations of the pressure near the left (closed) end of the channel. A laminar flow of an incompressible viscous fluid in a straight round tube with a nonstationary blow was in- vestigated in (1, 2). The stationary solution of this problem obtained in (3) (the rate of blow along the generatrix of the cylinder was assumed to be constant) shows that the disturbances arising near the left closed end of the tube lead to the formation of a plane acoustic field in it. The interaction of this field with the fluid blown into the tube leads to the generation of a vortex along its side surface. Between the side surface of the tube and the line found at a distance of half the radius of the tube from its symmetry axis, there arise large radial gradients of the axial flow velocity (4). The nonstationary calculations carried out in (5) show that the vorticity of a flow of an incompressible vis- cous fluid in a tube is inversely proportional to the Mach number, which is in agreement with the theoretical data (3, 6) and the numerical calculations (7). The axial derivative of the radial flow velocity is of the order of O(M 3 ), which is smaller than the radial derivative of the axial flow velocity. For simplicity, in (5), the case of disturbance of the rate of a fluid flow by the cosine law was considered. It has been established that the distribution of the vorticity front and its form are determined by the diffusion processes in the radial direction and the convective transfer in the axial direction. The diffusion of the vorticity in the direction of the tube axis results in the velocity of movement of the vorticity front of the compressible fluid being increased as compared to that of a nonviscous flow. The movement of the vorticity front in the nonstationary flow of an incompressible viscous fluid in a plane channel with a closed left end at small Mach numbers was investigated in (8), where the parabolic formulation of the problem was used. External nonstationary disturbances with different wave numbers were imposed on the rate of the blow. In the case of nonstationary blow, at the wall of the channel there arise comparatively large velocity and tem-

Continuous chemical HF laser with a modified radially expanding nozzle unit

dium. It was shown that the process of laser radiation generation involves only that part of the active medium that has fairly low values of the static pressure and temperature. Obviously, the creation of conditions for involving the entire volume of the active medium in the generation process is promising for further enhancement of HF laser energy parameters. This can be achieved, in particular, by adding an additional quantity of inert diluent to the active medium of the laser. In [2], we proposed a method for such addition. This method was realized in practice in an autonomous HF laser with a modified radially expanding nozzle unit of original design operating according to the "nozzle–injector–injector" scheme of mixing the reactants. The modified nozzle unit is equipped with a special injector for injecting a cold inert diluent at the inlet to the nozzle and thus realizing the above mixing scheme. Such injection permits separated supply of atomic fluorine and inert diluent into the nozzle, as well as two-region mixing of reactants with subsequent low-temperature flow of the oxidizing gas (mixture F+DF+He) in the supersonic parts of the nozzles. We have modified two available models of the laser under consideration. One of them is a small-size laser (the size of the outlet section of the nozzle unit is 18 × 3.9 cm) with a total mass flow of reactants m Σ 30 g ⁄ s. The other model ia a medium-size laser (the outlet section of the nozzle unit is 35 × 10 cm) with a total mass flow of reactants m Σ 140 g ⁄ s. The results of experiments with the small-size laser with a design power N = 5 kW [2, 3] have shown convincingly that the use of the new method of obtaining oxidizing gas makes it possible to enhance considerably the HF laser energy characteristics. For example, if 95% of the inert diluent (helium) is transferred from the first mixing zone (combustion chamber) to the second one (inlet part of the nozzles), then the laser power can increase by a factor of 2.5 and the specific energy of the laser can increase by a factor of 1.6 as compared to the characteristics of the base model. In the course of experiments with the medium-size HF laser (design power N 20 kW), its workability has been demonstrated. However, the energy characteristics of such a laser turned out to be lower than in the base model.

Numerical modeling of the processes within the combustion chamber of a solid propellant rocket engine during the stabilization of the design operation mode

Comprehensive numerical modeling of the processes occurring in the combustion chamber of a solid propellant rocket engine during the stabilization of the design operation mode is performed. The self-consistent problem considered includes nonstationary operation of an ignition device, warmup and ignition of a solid propellant charge followed by its nonstationary burning, nonstationary threephase homogeneous-heterogeneous flow of the combustion products in the combustion chamber, in the nozzle, and behind the engine nozzle unit, engine depressurization, and nozzle unit plug blowing-out. The results of the calculations are presented.

Oxygen-lance tips with a one-piece nozzle unit

Numerical simulation is used for critical analysis of existing designs to improve the cooling of oxygen-lance heads with a one-piece nozzle unit. The design and operation of the cooling system is optimized. The temperature field is calculated, and the thermal operation of the proposed oxygen-lance tips is considered.

Design and experimental studies on ceramic port cover for dual pulse motor

Material and definition of dome-shaped ceramic port cover contour is presented. Two types of ceramic port covers with equal thickness and variable thickness structures are proposed. A group of cold-flow tests was carried out on a reusable dual pulse motor in which the performances of different port covers including sealing, first-pulse pressure bearing and second-pulse broken pressure were experimentally studied. A solid dual pulse motor for hot-firing test was designed, manufactured and statically tested. The feasibility of proposed bulkhead with ceramic port cover employed on actual solid dual pulse motor was proved. It is found that dome-shaped port cover made from machinable glass ceramic withstands a high pressure on its convex side, but is prone to fragmentation while imposing a reasonably low pressure on its concave side. The peripherally thickened port cover that is more robust in machining and assembly process is recommended. Grooves milled on the port cover induce fragmentation and are helpful to produce regular broken aperture shape. The bulkhead assembly consists of retaining ring, port cover and supporting ring can well fulfill the requirements of port cover in fixing, preloading and sealing. The broken fragments are less likely to damage the insulation structures of the combustion chamber and the nozzle unit which had been validated in the test.

Design of Nozzle and Fin Locking Unit for MRECM Rocket: A Study

Design of Nozzle and Fin Locking Unit for MRECM Rocket: A Study

Flow structure of the active medium of a HF laser with a radially expanding nozzle unit

Measurements have been made of gasdynamic characteristics of the flow of the active medium as well as energy and spectral characteristics of radiation generated by a continuous chemical HF laser with a radially expanding nozzle unit. Based on the analysis of measurement results, the flow structure of the active medium has been determined, which is formed by the “nozzle–injector” reactant mixing scheme. It has been shown that only a part of the active medium is involved in the radiation generation. Measures for improving the efficiency of its use have been proposed.

The atomization of water–oil emulsions

The paper presents the results of experimental studies on atomization of the emulsions flowing through twin-fluid atomizers obtained by the use of the digital microphotography method. The main elements of the test installation were: nozzle, reservoir, pump and measurement units of liquid flow. The photographs were taken by a digital camera with automatic flash at exposure time of 1/8000 s and subsequently analyzed using Image Pro-Plus. The oils used were mineral oils 20–90, 20–70, 20–50 and 20–30. The studies were performed at flow rates of liquid phase changed from 0.0014 to 0.011 (dm 3/s) and gas phase changed from 0.28 to 1.4 (dm 3/s), respectively. The analysis of photos shows that the droplets being formed during the liquid atomization have very different sizes. The smallest droplets have diameters of the order of 10 μm. The experimental results showed that the changes in physical properties of a liquid phase lead to the significant changes in the spray characteristics. The analysis of the photos of water and emulsions atomization process showed that the droplet sizes are dependent on gas and liquid flow rates, construction of nozzle and properties of liquid. The differences between characteristics of atomization for water and emulsions have been observed. Analysis of photos on forming the droplets in air–water and air-emulsions systems showed that droplets are bigger in air-emulsion system (at the same value of gas to liquid mass ratio). The values of Sauter mean diameter (SMD) increased with increase of volume fraction of oil in emulsion. The droplet size increased with emulsion viscosity.