Nozzle Block Research Articles

Formulation of the problem of structured-element modeling of jet interference in a nozzle block

The objects of research are supersonic composite jet flows, as well as structural elements of flows (shock and acoustic waves, gas dynamic discontinuity surfaces), which act with each other and with various technical objects. Such objects may be structural elements or parts of special technical systems that experience loads during operation, or are subjected to targeted effects in order to improve their mechanical properties. The research is carried out in order to develop mathematical models describing the interaction of structural elements of the flow supersonic gas jets among themselves in composite jets. When performing the work, various methods allowing to model gas-jets flows and processes are considered. To solve the problem method of structured- element modeling of gas-jet processes was chosen [1–4]. This method focused on the creation of engineering methods for calculating launch gas-dynamics problems. The scope of application of the method can cover not only space roket, also civilian industry is in part where they face the problems of jet flow. For example with the need to improve the reliability of products, their strength and metal characteristics. The direction of subsequent theoretical and experimental research, which determine the development of the structural-element method, are determined and clarified.

The influence of gas heating on the calculated supersonic parameters of gas-powder flow at slag blower in the converter. Message 1

The article shows that one of the priority tasks in steel production technology is to increase the durability of the lining of oxygen converters. It is shown that the slag blower is a radical way to increase the durability of the lining of oxygen converters. When blowing the melt with oxygen, the MgO content in the slag is 6-8%. To increase the chemical affinity of the slag and the lining, it is proposed to blow the converter slag with jets of nitrogen or powder gas. To achieve optimal chemical affinity of the lining and slag, it is recommended to modify the latter by increasing the content of magnesium oxide in it to 12-14%. Increased durability of the lining makes it possible to solve the problem of replacing wasteful wastes of coal slag and changing environmental concerns on the excess media. It is shown that an attempt to increase the efficiency of modeling very complex processes of interaction of supersonic jets with converter slag has not yet been solved a. A critical analysis of existing methods for constructing mathematical models based on the use of known gas-dynamic laws of interaction of free turbulent jets with the melt is carried out. It has been established that only supersonic jets with their characteristic shock-wave structure always enter the slag melt. An integral method for calculating the parameters of a gas-powder flow in a supersonic nozzle taking into account the powder concentration is presented. It is determined how heating of the gas suspension affects the required pressure in front of the nozzle block, the speed and flow density in the outlet section of the supersonic nozzle. The gas dynamics system is connected to the heat exchange of the flowing gas-dispersed mixture in the Laval expansion nozzles to establish the heating effect in front of the nozzle block of the two-phase gas suspension to a temperature that will ensure The increase in the fluidity of the gas flow is doubled and its kinetic energy is increased threefold. The method of expanding the parameters of the gas-powder flow between the Laval expansion nozzle involves the infusion of 10 physical effects into 14 parameters of the gas-powder flow. It is shown that numerical expansions allow the tuyere body to be used as a heat exchanger for heating the gas suspension, as well as for increasing the pressure of the gas-powder jet that flows from the nozzles

3D investigation of heat exchange and hydrodynamics of high pressure turbine nozzle block platforms with different cooling schemes

Turbine nozzle blocks were tested and, as a result, problems of nozzle block lower platform alligatoring were detected. In the course of the research possible variants of cooling high pressure turbine nozzle block vane platforms were investigated. According to the results of 3D ANSYS CFX calculation the cooling efficiency of high pressure turbine vane platforms with film cooling and convective-film cooling were compared. Research was carried out to eliminate the alligatoring defect of the lower vane platform with convective cooling. Necessary changes in the design were made due to which the cooling air from the secondary combustion chamber area was redistributed over the surface of the turbine nozzle block lower platform. To force the gas turbine engine to the inlet gas temperature to 1800К and more, and to increase the cooling air mass flow from the secondary combustion chamber area over the platforms using convective cooling methods not requiring developed ribbing and impingement cooling, areas of the platforms, as well as zones demanding insignificant intensity of cooling are shown.

The Adaptive Composite Block-Structured Grid Calculation of the Gas-Dynamic Characteristics of an Aircraft Moving in a Gas Environment

This paper considers the problem associated with the numerical simulation of the interaction between the cocurrent stream occurring near a monoblock moving in the gas medium and solid fuel combustion products flowing from a solid fuel rocket engine (SFRE). The peculiarity of the approach used is the description of gas-dynamic processes inside the combustion chamber, in the nozzle block, and the down jet based on a single calculation methodology. In the formulated numerical methodology, the calculation of gas-dynamic parameters is based on the solution of unsteady Navier–Stokes equations and the application of a hybrid computational grid. A hybrid block-structured computational grid makes it possible to calculate gas flow near bodies of complex geometric shapes. The simulation of the main phase of interaction, corresponding to the stationary mode of rocket flight in the Earth’s atmosphere, has been carried out. A conjugated simulation of the internal ballistics of SFRE and interaction of combustion products jets is conducted.

3D printing technologies for creating models and nozzles in an aerodynamic shock tunnel experiment

The features of 3D printing method for rapid prototyping and manufacturing of models for a pulsed high-speed gas-dynamic experiment are considered. Modern additive technologies allow the production of models. The basic properties of the materials and the advantages of 3D printing methods are described. The structure and properties of the obtained models can be unattainable using traditional manufacturing techniques. The design of the wind tunnel nozzle block is considered, which provides for the production of profiled contours using 3D printing. The advantages and disadvantages of use of such units on the shock tube are considered.

Fluid Dynamics of Thrust Vectorable Submerged Nozzle

A numerical simulation of the gas-dynamic processes in the thrust vectorable nozzle of the solid rocket motor is considered. Construction of a geometric model and a generation of computational mesh, and reconstruction of model and mesh at each time step are discussed. Calculations of the flowfield of combustion products in the pre-nozzle chamber and nozzle block are carried out for various angles of nozzle rotation. The distributions of the gas dynamic quantities in the pre-nozzle volume corresponding to the outflow of the combustion products from the cylindrical channel and star-shaped channel are compared, as well as the solutions of the problem obtained with quasi-stationary and unsteady formulations. The effects of the channel shape on the distribution of flow quantities and formation of a vortical flow structure in the nozzle block are discussed.

Influence of gas-dynamic characteristics of a wide-range engine on energy-information exchange during flights at high supersonic speed

Using a conical nozzle as an example, the gas-dynamic and thrust characteristics of high-altitude nozzles are studied in a wide range of atmospheric pressures. A geometric model of the nozzle block and the computational domain is developed in a two-dimensional axisymmetric formulation. A calculation was carried out with setting the parameters of the standard atmosphere in the altitude range from 0 to 80 km. In one of the parts of this work, the most common shock-wave structures (triple configurations of shock waves) that arise during flights at supersonic and high supersonic speeds are considered, during jet outflows from propulsion systems. We also studied the influence of the extreme values of the discontinuities of the flow field parameters on the transmitted electromagnetic signals.

Laboratory simulation for single and block supersonic jets

Model experimental studies are presented for the flow field of a single jet, the flow parameters of a block jet, the pressure distribution on the bottom screen, and the parameters of the jet flow from a model nozzle. When expanding into a vacuum and/or a highly rarefied medium, the conditions for reproducing the relative gas pulse value of the full-scale nozzle block section are met. It is shown that when using specific similarity criteria, it is possible to experimentally model the supersonic jet outflow processes of space vehicles on small-sized laboratory vacuum installations, similar to the one created at Novosibirsk State University. Simulation results using spectral density measurements based on the glow excited by a focused electron beam, longitudinal and transverse jet density profiles obtained using modern scanning technology, as well as measurements of bottom pressure near the nozzle block are given. The possibilities and features of each applied registration method are discussed.

Efficiency of using nitrogen trifluoride as an oxidiser in a supersonic continuous-wave chemical HF laser

We report the results of an experimental study of possible ways to increase the efficiency of using NF3 nitrogen trifluoride as an oxidiser in an atomic fluorine generator of a supersonic continuous-wave chemical HF laser with a flat nozzle block corresponding to the nozzle – nozzle reagent mixing scheme. As such ways, we consider increasing the residence time of reagents in the combustion chamber and rising temperature in the chemical reaction zone. Comparison of specific energy characteristics of an HF laser operating with the use of the studied (NF3) and ‘basic’ (F2) oxidisers shows that the replacement of molecular fluorine with nitrogen trifluoride during the burning with deuterium in the combustion chamber of an atomic fluorine generator with allowance for the proposed measures leads to a reduction in the specific laser energy output by no more than 23 % – 24 % at high burning completeness.

ЧИСЛЕННОЕ ИССЛЕДОВАНИЕ ДИНАМИКИ ВНУТРИКАМЕРНЫХ ПРОЦЕССОВ В РАКЕТНОМ ДВИГАТЕЛЕ ДЛЯ МОБИЛЬНЫХ КОМПЛЕКСОВ С МНОГОШАШЕЧНЫМ ПОРОХОВЫМ ЗАРЯДОМ

A solid-fuel rocket engine is a complex technical system in which a number of interrelated non – stationary and substantially nonlinear physical and chemical processes simultaneously occur. The type of SFRE under consideration has its own problems and design features. To optimize the parameters of a rocket engine, we study the dynamics of its internal processes. The research method is to set up a computational experiment. We consider the conjugate statement of the problem, which includes: triggering of the ignition device; – heating, ignition and subsequent unsteady and turbulent combustion of the powder charge; – unsteady threedimensional shock wave and a vortex of homogeneous-heterogeneous flow of air and products of combustion in the combustion chamber, nozzle block and launchers unit; – depressurization of the combustion chamber and the subsequent departure of the stub nozzle block. Each of the subtasks is considered in a relationship and resolved simultaneously - at a single time step. As a result of researches it is established that when triggered, the solid-propellant in the combustion chamber is implemented by an abnormal process associated with the segregation of the combustion mode of multi-turret powder charge. The results of numerical calculations are presented, on the basis of which constructive measures are developed to eliminate this undesirable effect.

Energy characteristics of a supersonic continuous-wave chemical HF laser using hydrazine decomposition products

We report the results of calculations and experimental studies of specific energy characteristics of a supersonic cw chemical HF laser with a flat nozzle block corresponding to the nozzle – nozzle reagent mixing scheme, in which catalytic decomposition products of hydrazine N2H4 (H2 + N2 + NH3) are used as a secondary fuel. As a result of experiments with cold (300 K) model mixtures, the specific energy extraction of the laser is found to decrease in this case by 43 % compared with the laser utilising pure hydrogen. The calculations show that the main reason for a decrease in the specific energy of the laser is an increase in the temperature in the mixing zone of the oxidising gas and secondary fuel jets. A strong effect of ammonia is revealed. Taking into account the actual heating of the products (up to 1000 K) during the catalytic decomposition of N2H4 allows the level of specific energy extraction from the laser to approach that of energy extraction from the laser operated on pure hydrogen by 13 %, which will lead to a decrease in the specific energy extraction by only 30 % in the absence of NH3 decomposition products.

Renewal of Elements and Construction Units of Gas Turbine Engines by Means EBW

Renewal of gas turbine engines (GTE) is very urgent and at the same time highly complicated technical task. A cost effective alternative to new replacement parts is the restoration of the damaged or worn construction units and elements of GTE, including compressor and fan blades, as well as guide cases and hydraulic cylinders of nozzle block. The work contains the results of the development of reliable and efficient methods of gas turbine parts renewal by means electron beam welding. The technology of repair of three types of blade airfoil defects, replacement of damaged guide vanes and restoration of worn hydraulic cylinders was mastered. It is confirmed that electron beam welding is ideal for the solution of aircraft GTE construction units repair problems.

Behavior of Low-Velocity Detonation in Stoichiometric Mixture of Ammonium Perchlorate and Polymethyl Methacrylate

Low-velocity detonation in mixtures of ammonium perchlorate and fuel additives in high relative density charges is an interesting subject for the scientific research, with potential for practical applications in pulse nozzle and projective setups. However, information about the process is scanty and mainly concerns the measurements of the wave propagation velocities. This paper describes the results of a research aimed at obtaining the data base on properties and behavior of low-velocity detonation (LVD) in pressed charges of the mixture of ammonium perchlorate and 15% polymethyl methacrylate. The firings have been fulfilled at the pulse laboratory projectile setup and the strong steel confinements equipped with the nozzle block or a projectile with the process initiated by a booster produced from RDX or the TNT/RDX 30/70 mixture. The thrust impulse, trajectory of the projectile, pressure, and LVD wave front trajectory have been recorded. According to the measurement results, the muzzle velocity, the pressure at the projectile, and the burning completeness of the mixture have been calculated. In the experiments, the relative charge density has varied from 0.85 to 0.96, the ammonium perchlorate particle size has been from 20 to 200 μm, and the charge length and the projectile mass have varied as well. The experiments were supplemented with numerical simulation. Emphasis was lain on the interaction of a low-velocity detonation wave with end rarefaction waves. The conditions under which the high completeness of chemical conversion of the mixture can be reached with the acceptable level of the maximum pressure (1–1.5 GPa) are considered.

Perfection of cooling systems of overhead tuyeres heads of 250-t BOFs

Deterioration of tips cooling as a result of number of nuzzles increase in tuyere heads does not allow to use multinozzle (six and more) overhead tuyeres for increasing of steel melting technical and economical indices and operating characteristics of technological equipment. The main reason of it is as follows: deterioration ofcooling results in over-heating and burnt-outof tips material in the farthest nozzle zone following the overhead tuyeres breakage. To avoid the water stagnant areas in the farthestnozzle zones of the heads cooling route and therefore to increase the overheads oxygen tuyeres of 250-t BOF operation life, a new design of the six-nozzle tuyere head with asymmetric cooling of tips farthest zones elaborated, manufactures and tested. The perfection of the six-nozzle heads cooling system included asymmetric (relating the side surface of the nozzle block) installation behind every nozzle (in the water direction) a guidingblade of special design. It enabled to increase to a maximum degree the heat removal efficiency from the internal surface in the tip farthest zones and had a positive effect on the overhead tuyeres heads resistance. The workability of the proposed design of the six-nozzle tuyere head with asymmetric cooling of farthest zones was confirmed during test-industrial heats at 250-t BOFs of OJSC “Dneprovskysteel-works”. The heats were carried out with oxygen consumption of 800–1200 m 3/min and regime of partial afterburning ofexit gases. The water consumption for tuyeres cooling decrease from 320–340 m 3 /h, at that the water temperature difference at the tuyere entry and exit varied in the range of 11–16 °C depending on blow-down duration. Application of the new design of the six-nozzle tuyere head with asymmetric farthest zones cooling enabled to increase the sixnozzle heads resistance by a factor 1.287 comparing with six-nozzle heads without farthest zones cooling and by a factor of 3.327 comparing with regular five-nozzle tuyere heads. The effect reached thanks to more rational cooler distribution and increase ofits velocity. The metal pick up of shafts of the six-nozzle tuyere head with asymmetric farthest zones cooling: while the five-nozzle tuyeres were taken off for salamander cutting off after 1–5 heats, the six-nozzle tuyeres were taken off for the salamander cutting off after 79–81 heats. It indicated a higher efficiency of heat running blow-down and slag regimes with application of proposed design of the six-nozzle tuyere head with asymmetric farthest zones cooling.

Increasing of Precision Technology of Glass Sorting Based on Very Fast Reconfigurable Image Processing

The paper deals with a method and technology for increasing of precision sorting of transparent materials - glass. The recycled glass is a valuable material which is necessary as an ingredient in the process of glass manufacturing. We propose a very fast industrial device based on FPGA (field-programmable gate array) image processing along with a novel algorithm for a robust real-time treatment of acquired data. The system consists from a line-scan camera with fast CameraLink interface, FPGA processing, battery of valves propelled via pneumatics and nozzle block. Very important part of the system is a background configuration software enables precise assessment of required limits as inputs to FPGA processing. The overall performance is discussed from the perspective of laboratory and industrial tests. The proposed FPGA image processing can be utilized for further future enhancements in the field of precise sorting of glass with stuck labels on it. The results give very good performance even in the industrial environment with a lot of dust and dirt and hence the glass does not need to be extensively cleaned.

Parameters of the air flow formed by the interchangeable nozzles with the transformed critical part

The results of studies of the nozzle block functioning with interchangeable nozzles at the hypersonic aerodynamic shock tube (HAST) are presented. Air flow parameters from the elongated nozzle and of variety of critical cross-sections of the inlet of the nozzle were calculated. The dependence of the influence of the nozzle critical section size on the uniformity of incoming flow and speed was shown. The calculated pressure values were compared with those measured experimentally at the nozzle exit cut and at different distances from it.

Investigation of gas dynamic parameters of the conical nozzle block functioning in the Hypersonic Aerodynamic Shock Tube

The results of investigations of the conical nozzle block of the hypersonic shock aerodynamic tube (HAST) [1–4] of the Laboratory of Radiative Gas Dynamics of the Institute for Problems in Mechanics RAS are presented. The efficiency of short conical nozzle is calculated. The gas dynamic flow parameters were measured experimentally at different distances from the nozzle exit. The design pressure values are compared with the measurements at the nozzle outlet. Comparison of numerical calculation and experimental results shows that the nozzle is started, successfully worked and it is possible to obtain a uniform flow at Mach numbers M = 5...7.

Analysis of possibilities of high-speed prototyping technology in hot section manufacturing

The article is devoted to the exercising of a trial technological process for the manufacture of gas turbine engine (GTE) hot sections by the example of a solid-cast nozzle block. To do this, the authors made up a plan of the experiment associated with the search for optimal conditions and parameters of a technological process of the sector master mold layer-by-layer synthesis from a photopolymeric material. The paper tracks the interconnection between the parameters of a 3D printing system Objet Eden 350 and the materials in the growing process by the PolyJet technology and mechanical properties of a master mold in the context of their influence on the surface layer quality and geometric accuracy of the final GTE parts’ casting. Based upon the analysis of the obtained research results and taking into account technical requirements, the authors managed to grow a nozzle block sector master mold, get wax models and conduct an experimental casting of a solid cast nozzle block wheel.

The calculation of the asymmetrical three-dimensional flow of the combustion products in a compact size SRM

The article is devoted to the problem of calculating the complex flow of combustion products in the solid propellant combustion chamber. The paper presents a calculation of the combustion products flow for three instants of time using the example of an engine for removing of the rocket head fairing. Due to the fact that the nozzle block of the engine is divided into four nozzles, one of which has a larger diameter of the critical section, the gas flow along the internal free volume of the engine is asymmetrical. ANSYS (CFX) software package is used to solve this problem.The article gives a brief description of the engine design and the charge of solid fuel for which calculations are performed. To get out calculations, 3D models of internal free volumes created in Autodesk Inventor are used. Grid is generated in the standard ANSYS ICEM CFD package, which is integrated into the ANSYS (CFX) working environment. Calculation results are given after describing the boundary conditions. The results are presented as a velocity distribution in two mutually perpendicular planes.The proposed methodology for the gas-dynamic calculation of SRM allowed obtaining calculations of higher accuracy in comparison with engineering methods. The approach to the solution of the problem proposed in this article can be widely used not only in the design of drive engines, but other SRMs for various purposes.A

DETERMINATION OF THE TYPE OF A SINGLE-USE GRENADE LAUNCHER BASED ON ITS COMPOSITE PARTS AND FRAGMENTS OF REACTIVE GRENADE FOUND AT THE PLACE OF ACCIDENT

In carrying out an investigation into the explosion, among others, the investigative version of the use of a single-use reactive grenade launcher is being considered. The most common for criminal explosions are applied grenade launchers RPG-18, RPG-22, RPG-26. Their use is due to a number of such properties as small size and weight, which makes it possible to transfer them covertly, the range of the shot significantly exceeding the range of the hand grenade throw, the high detonating effect of the rocket grenade explosion. The single-use rocket launchers are generally of the same design. Their differences are in the features of the components construction and dimensional characteristics, which are given in the article. On the basis of expert practice, details ofgrenade launchers that remain at the site of the explosion and have the least damage are determined. These details are the objects of investigation of the explosion technical expertise. These objects include launchers of grenade launchers and rocket parts ofjet grenades. The design features of the launchers, their dimensional characteristics and marking symbols make it possible to determine their belonging to a specific type of jet grenade launchers. Missile parts of jet grenades differ in the form of the combustion chamber of the jet engine, nozzle, in the size ofthe outlet section of the nozzle, in the form and size of the stabilizerfeathers. To determine the belonging of the rocket part of the grenade to a specific type ofjet grenade launcher, it’s necessary to establish a set of structural features and dimensional characteristics. At considerable damage of the combustion chamber of the jet engine, as a rule, the nozzle block remains intact that allows to define diameter of critical section of a nozzle, and on it to establish type of the used single-use grenade launcher.