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.

NUMERICAL STUDY OF DYNAMICS INTRACHAMBER PROCESSES IN SOLID PROPELLANT SUSTAINER TAKING INTO ACCOUNT FLIGHT OVERLOADS. PART 1. CALCULATION METHOD

The dynamics of transient in-chamber processes (internal ballistics) of the cruise missile's second-stage cruise missile propulsion system is studied, taking into account, in the general case, distributed spatially-three-dimensional and time-varying flight overloads. The research method is the formulation of a computational experiment. Be considered coupled formulation of the problem, including: – transient triggering of igniter device (the rate of combustion of the igniting composition is described on the basis of experimental and theoretical approach afterburn combustion products in case igniting device); preheating, ignition and subsequent unsteady and turbulent combustion of solid propellant charge (used quasi-homogeneous combustion model based on the equations of heat conduction and chemical kinetics recorded for a condensed phase (solid fuel), taking into account the influence of the gas phase (torch) on the process of combustion in the condensed phase; the method of solving the problem – finite difference method); – non-stationary three-dimensional homogeneous-heterogeneous four phase flow of air and products of combustion in the combustion chamber, the nozzle block and the block launchers rocket engine (used approaches of continuum mechanics of multiphase media; the basic system of equations system of vortex differential equations of gas dynamics solution method – a multi-parameter class of difference schemes of splitting into physical processes of the method Davydova); – depressurization of the combustion chamber of the SRB (equation of motion of the plug nozzle block – Newton's second law; the proposed solution method – Euler's method). Each of the subtasks is considered in a relationship and resolved simultaneously – at one time step. To solve the formulated problem, a set of application programs has been developed using (for the main calculation module) the OpenCL multithreaded information processing standard. The performance of the software product was checked.

NUMERICAL STUDY OF THE DYNAMICS OF INTRA-CHAMBER PROCESSES IN A ROCKET ENGINE FOR MOBILE COMPLEXES WITH A MULTI-TURRET POWDER CHARGE

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.

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.

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.

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.

New Structure and Manufacturing Process of Integral Nozzle Block

The nozzle block is one of the most important parts of steam turbine. It puts the steam heat energy into kinetic energy and plays a guiding role to the steam flow. The open integral nozzle block is a very unique structure. Due to the restriction of the large steam passage bending degree and the small nozzle mouth, the traditional process is difficult and the production efficiency is low. This paper mainly studies the structure and processing method of a new open integral nozzle block. The difficulties of the manufacturing process are being solved one by one by the way of developing the five-axis NC program, designing the special tooling and making the process technical solution. The process technical solution is to split the whole complex structure into three main parts which are easy to machine. It can easily realize the surface finishing of the steam passage and guarantee the geometric dimension of each steam blade. The surface roughness of the steam passage can reach Ra0.8. The precision requirements for machining and assembling of the open integral nozzle block can be fully met. It has a wide application prospect in promoting the scientific and technological progress of the new structure and the new process.