scholarly journals Multivariable Backstepping and Adaptive LQ Control of Thermoacoustic Coupling in Jet Engine Systems

2015 ◽  
Author(s):  
Zackary Knoll
Keyword(s):  
Jet Engine ◽  
Engine Systems ◽  
Lq Control ◽  
Thermoacoustic Coupling

Weak Extinction Limits of Large-Scale Flameholders

1992 ◽  
Vol 114 (4) ◽  
pp. 776-782 ◽  
Author(s):  
M. R. Baxter ◽  
A. H. Lefebvre
Keyword(s):  
Large Scale ◽  
Liquid Hydrocarbon ◽  
Operating Conditions ◽  
Extinction Data ◽  
Jet Engine ◽  
Lean Blowout ◽  
Stirred Reactor ◽  
Experimental Apparatus ◽  
Varied Composition ◽  
Engine Systems

Weak extinction data obtained from an experimental apparatus designed to simulate the characteristics of practical afterburner combustion systems are presented. The apparatus supplies mixtures of varied composition (equivalence ratio and degree of vitiation), temperature and velocity to Vee-gutter flame holders of various widths and shapes similar to those found in jet engine systems. The fuel employed is a liquid hydrocarbon whose chemical composition and physical properties correspond to those of aviation kerosine, JP5. An equation for predicting weak extinction limits which accounts for upstream vitiation and the chemical characteristics of the fuel is derived from stirred reactor theory. The correlation between the predictions and experimental results indicates that the stirred reactor approach can provide a framework for predicting the lean blowout limits of practical flameholders over wide ranges of engine operating conditions.

scholarly journals Use of a “green” propellant in low-thrust control jet engine systems

2021 ◽  
Vol 2021 (4) ◽  
pp. 29-43
Author(s):  
V.I. Timoshenko ◽  
◽  
L.K. Patryliak ◽  
Yu.V. Knyshenko ◽  
V.M. Durachenko ◽  
...  
Keyword(s):  
The State ◽  
Low Thrust ◽  
Fuel Component ◽  
Jet Engine ◽  
Engine Thrust ◽  
Thrust Characteristics ◽  
Green Propellants ◽  
Green Propellant ◽  
Engine Systems

The aim of this work is to analyze the state of the art in the development and use of pollution-free (“green”) propellants in low-thrust jet engines used as actuators of spacecraft stabilization and flight control systems and to adapt computational methods to the determination of “green”-propellant engine thrust characteristics. The monopropellant that is now widely used in the above-mentioned engines is hydrazine, whose decomposition produces a jet thrust due to the gaseous reaction products flowing out of a supersonic nozzle. Because of the high toxicity of hydrazine and the complex technology of hydrazine filling, it is important to search for its less toxic substitutes that would compare well with it in energy and mass characteristics. A promising line of this substitution is the use of ion liquids classed with “green” ones. The main components of these propellants are a water solution of an ion liquid and a fuel component. The exothermic thermocatalytic decomposition of a “green” propellant is combined with the combustion of its fuel component and increases the combustion chamber pressure due to the formation of gaseous products, which produces an engine thrust. It is well known that a “green” propellant itself and the products of its decomposition and combustion are far less toxic that hydrazine and the products of its decomposition, The paper presents data on foreign developments of “green” propellants of different types, which are under test in ground (bench) conditions and on a number of spacecraft. The key parameter that governs the efficiency of the jet propulsion system thrust characteristics is the performance of the decomposition and combustion products, which depends on their temperature and chemical composition. The use of equilibrium high-temperature process calculation methods for this purpose is too idealized and calls for experimental verification. Besides, a substantial contribution to the end effect is made by the design features of propellant feed and flow through a fine-dispersed catalyst layer aimed at maximizing the monopropellant-catalyst contact area. As a result, in addition to the computational determination of the thrust characteristics of a propulsion system under design, its experimental tryout is mandatory. The literature gives information on the performance data of “green”-propellant propulsion systems for single engines. However, in spacecraft control engine systems their number may amount to 8–16; in addition, they operate in different regimes and may differ in thrust/throttling characteristics, which leads to unstable propellant feed to operating engines. To predict these processes, the paper suggests a mathematical model developed at the Institute of Technical Mechanics of the National Academy of Sciences of Ukraine and the State Space Agency of Ukraine and adapted to “green”-propellant engine systems. The model serves to calculate the operation of low-thrust jet engine systems and describes the propellant flow in propellant feed lines, propellant valves, and combustion chambers. To implement the model, use was made of the results of experimental studies on a prototype “green”-propellant engine developed at Yuzhnoye State Design Office. The analysis of the experimental results made it possible to refine the performance parameters of the monopropellant employed and obtain computational data that may be used in analyzing the operation of a single engine or an engine system on this propellant type in ground and flight conditions

scholarly journals Weak Extinction Limits of Large Scale Flameholders

1991 ◽  
Author(s):  
M. R. Baxter ◽  
A. H. Lefebvre
Keyword(s):  
Large Scale ◽  
Liquid Hydrocarbon ◽  
Operating Conditions ◽  
Extinction Data ◽  
Jet Engine ◽  
Lean Blowout ◽  
Stirred Reactor ◽  
Experimental Apparatus ◽  
Varied Composition ◽  
Engine Systems

Weak extinction data obtained from an experimental apparatus designed to simulate the characteristics of practical afterburner combustion systems are presented. The apparatus supplies mixtures of varied composition (equivalence ratio and degree of vitiation), temperature and velocity to Vee-gutter flame holders of various widths and shapes similar to those found in jet engine systems. The fuel employed is a liquid hydrocarbon whose chemical composition and physical properties correspond to those of aviation kerosine, JP5. An equation for predicting weak extinction limits which accounts for upstream vitiation and the chemical characteristics of the fuel is derived from stirred reactor theory. The correlation between the predictions and experimental results indicates that the stirred reactor approach can provide a framework for predicting the lean blowout limits of practical flameholders over wide ranges of engine operating conditions.

A Modal Transient Rotordynamic Model for Dual-Rotor Jet Engine Systems

1976 ◽  
Vol 98 (3) ◽  
pp. 876-882 ◽  
Author(s):  
D. W. Childs
Keyword(s):  
Simulation Model ◽  
High Speed ◽  
Model Development ◽  
Rigid Bodies ◽  
Turbine Wheel ◽  
Jet Engine ◽  
Modal Damping ◽  
Gyroscopic Effects ◽  
Case Structure ◽  
Engine Systems

A transient modal simulation model is developed for a “typical” two-spool jet engine configuration, consisting of a low-speed rotor, a high-speed rotor, and the supporting case structure. The formulation cited permits bearing connections from a rotor to the support structure and between rotors. A conventional Jeffcott-Green flexible rotor formulation is used to model each rotor as a collection of rigid bodies connected by a mass-less elastic structure. The case structure is similarly modeled as a collection of axisymmetric elastically connected rigid bodies. The transient modal simulation model development is based on eigendata for the complete structural dynamics model (elastically coupled rotors and case structure) at zero running speed. The completed model readily accounts for gyroscopic effects, bearing damping and nonlinearities, structural modal damping, concentrated damping due to oil-film dampers, etc. The applicability and utility of the model is demonstrated by the simulation of a turbine-wheel blade loss.

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

2017 ◽  
Vol 17 ◽  
pp. 245-252
Author(s):  
V. V. Somov
Keyword(s):  
Combustion Chamber ◽  
Structural Features ◽  
Outlet Section ◽  
Technical Expertise ◽  
Jet Engine ◽  
Size Ofthe ◽  
Single Use ◽  
Nozzle Block ◽  
Considerable Damage

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.

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