Thermodynamic Analysis of a Jet Engine Using a Liquid Propellant

Combustion-chamber is a critical component of the propulsion engine, which is widelyused in the space industry and aeronautics. The goal of this article is to perform a numericalanalysis on the combustion process using a liquid-type propellant. The steps that must be followeduntil total combustion is achieved are emphasized. It concerns the fuel feeding phase, its injectionand the combustion operation. The amount of combustion products and the energy generated areevaluated. It has been shown that the liquid propellant may present an efficient alternative fuelthan the kerosene. In addition, the temperature of combustion does not exceed a certain limit toavoid structural problems in the chamber. The parametric survey allowed determining the range ofthe most influence factors, including the pressure, mixture richness, velocity and flow rates ofinjection for the fuel and oxidizer. The number and type of injectors revealed a considerableinfluence on the velocity and flow rates of injection. To maximize thrust force and systempropulsion, a careful selection of chamber material and ignition methods is required. A thorough inspection on the issues of walls cooling showed the necessary survey of maximum temperaturesthat may be reached during the combustion. Finally, an investigation of the thermal exchangethrough the walls will be very interesting.

Use of a “green” propellant in low-thrust control jet 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

Combining Macro- and Mesoscale Optimization: A Case Study of the General Electric Jet Engine Bracket

Topology optimization (TO) is a mathematical method that optimizes the material layout in a pre-defined design domain. Its theoretical background is widely known for macro-, meso-, and microscale levels of a structure. The macroscale TO is now available in the majority of commercial TO software, while only a few software packages offer a mesoscale TO with the design and optimization of lattice structures. However, they still lack a practical simultaneous macro–mesoscale TO. It is not clear to the designers how they can combine and apply TO at different levels. In this paper, a two-scale TO is conducted using the homogenization theory at both the macro- and mesoscale structural levels. In this way, the benefits of the existence and optimization of mesoscale structures were researched. For this reason, as a case study, a commercial example of the known jet engine bracket from General Electric (GE bracket) was used. Different optimization workflows were implemented in order to develop alternative design concepts of the same mass. The design concepts were compared with respect to their weight, strength, and simulation time for the given load cases. In addition, the lightest design concept among them was identified.

Aerothermodynamics and Jet Propulsion

Get up to speed with this robust introduction to the aerothermodynamics principles underpinning jet propulsion, and learn how to apply these principles to jet engine components. Suitable for undergraduate students in aerospace and mechanical engineering, and for professional engineers working in jet propulsion, this textbook includes consistent emphasis on fundamental phenomena and key governing equations, providing students with a solid theoretical grounding on which to build practical understanding; clear derivations from first principles, enabling students to follow the reasoning behind key assumptions and decisions, and successfully apply these approaches to new problems; practical examples grounded in real-world jet propulsion scenarios illustrate new concepts throughout the book, giving students an early introduction to jet and rocket engine considerations; and online materials for course instructors, including solutions, figures, and software resources, to enhance student teaching.

A Novel Automatic Algorithm for Estimating the Jet Engine Blade Number of Insufficient JEM Signals

One of the major issues in multifunction radars is time resource allocation to maximize the radar’s ability. If jet engine modulation (JEM) is more efficiently performed in an insufficient dwell-time environment, the remaining time can be allocated for other tasks. This study presents a novel automatic algorithm for estimating the jet engine blade number of insufficient JEM signals. We employed a harmonic selection rule and a modified empirical mode decomposition (EMD) with an adaptive low-pass filtering. For a refined autocorrelation waveform, the analysis focuses on a desirable combination of intrinsic mode functions derived from the modified EMD. The approach is significant because it enables reliable estimation despite the insufficient JEM signal. Also, the proposed algorithm is innovative because it uses only the time-domain method, not the frequency-domain method. The application is expected to enhance the efficiency of radar resource management.