Trends in Military Aircraft Propulsion

1989 ◽  
Vol 203 (1) ◽  
pp. 11-23
Author(s):  
R M Denning ◽  
N A Mitchell
Keyword(s):  
Aircraft Engine ◽  
Development Programme ◽  
Military Aircraft ◽  
Engine Design ◽  
Combat Aircraft ◽  
Major Parameter ◽  
Specific Thrust ◽  
Major Factors ◽  
Vertical Landing ◽  
Engine Cycle

The major factors determining the choice of engine cycle for a combat aircraft are the requirements of the design mission and those of aircraft speed and agility. The requirement for jet-borne flight in short take-off vertical landing (STOVL) aircraft imposes further demands on cycle and configuration. The changing nature of combat aircraft requirements is the reason for changes in engine design. Specific thrust is shown to be the major parameter defining engine suitability for a particular role. An examination of mixed turbofan characteristics shows that specific thrust is also the key to understanding the relationships between engine characteristics. The future development of combat engines is discussed, in particular the implications of stoichiometric limits on cycle temperatures and the benefits of variable cycle engines are examined. Recent work on advanced STOVL (ASTOVL) aircraft is reviewed and aircraft/engine concepts designed to meet the requirements of the role are assessed. Experience shows that the technology for these advanced engines must be fully demonstrated before production to minimize the risks and costs of the development programme.

Areo-Engine Cycle Parametric Analysis and Installed Performance Calculation Based on Aircraft Flight Mission

2013 ◽  
Vol 482 ◽  
pp. 277-281 ◽  
Author(s):  
Hong Zhou ◽  
Zhan Xue Wang ◽  
Xiao Bo Zhang
Keyword(s):  
Parametric Analysis ◽  
Engine Performance ◽  
Aircraft Engine ◽  
Operating Conditions ◽  
Aircraft Flight ◽  
Performance Requirements ◽  
Engine Design ◽  
Performance Specifications ◽  
Performance Calculation ◽  
Engine Cycle

The aircraft/engine integration design numerical simulation model was established. The engine design performance specifications were obtained by calculating aircraft lift-drag characteristics, mission analysis, constraint analysis. Combining engine cycle parametric analysis with installation loss computing, the engine performance parameters can be found, which meet the aircraft flight envelope performance requirements. Taking double bypass variable cycle engine as an example to check the model, the results show that the variable cycle engine can meet aircrafts thrust and fuel consumption demands under different operating conditions, and achieve cruise thrust adjustment at the same inlet mass flow to reduce installation losses.

Estimating Gas Turbine Engine Weight, Costs, and Development Time During the Preliminary Aircraft Engine Design Process

2013 ◽  
Author(s):  
Aaron R. Byerley ◽  
August J. Rolling ◽  
Kenneth W. Van Treuren
Keyword(s):  
Risk Factors ◽  
Gas Turbine ◽  
Design Process ◽  
Development Time ◽  
Aircraft Engine ◽  
Engineering Majors ◽  
Cost Estimating ◽  
Engine Design ◽  
Aeronautical Engineering ◽  
Engine Cycle

This paper describes the application of a weight and cost-estimating methodology used in an undergraduate aircraft engine design course that is taught in concert with a companion course in airframe design. The two preliminary designs, one for the engine and the other for the airframe, must be integrated as subsystems within a system to satisfy the performance requirements of a given mission as outlined in a single “request for proposals”. In recent years, systems engineering management majors have been added to the design teams to work alongside the aeronautical engineering majors to analyze and report on costs, schedule, and technical risk factors in addition to the operational performance factors that have previously been the sole focus of the course. The teaming of technical management majors and aeronautical engineering majors has been driven by a heightened emphasis on system affordability. The cost-estimating methodology for gas turbine engines uses cycle parameters such as turbine rotor inlet temperature, overall pressure ratio, specific fuel consumption, level of technology, and engine dry weight as inputs. A methodology for estimating dry engine weight was developed which uses engine cycle parameters and fan face diameter as inputs in a volume analog scaling factor which was correlated against historical engine weight data. To tie all of the performance, weight, cost, and development time issues together, the paper presents an “analysis of alternatives” example that considers three different engine cycle alternatives. The design tools presented in this paper will provide a strong foundational understanding of how to systematically weigh and evaluate the important tradeoffs between aircraft turbofan engine performance, cost, schedule, and risk factors. Equipping students with the insight and ability to perform these multidisciplinary trade studies during the preliminary engine design process is this paper’s most important contribution.

Exploring GasTurb 12 for Supplementary Use on an Introductory Propulsion Design Project

2017 ◽  
Author(s):  
Aaron R. Byerley ◽  
Kurt P. Rouser ◽  
Devin O. O’Dowd
Keyword(s):  
System Analysis ◽  
Pressure Ratio ◽  
Supplementary Information ◽  
Design System ◽  
Inlet Temperature ◽  
Turbofan Engine ◽  
Design Project ◽  
Engine Design ◽  
Aeronautical Engineering ◽  
Engine Cycle

The purpose of this paper is to explore GasTurb 12, a commercial gas turbine engine performance simulation program, for supplementary use on an introductory propulsion design project in an undergraduate course. This paper will describe several possible opportunities for supplementing AEDsys (Aircraft Engine Design System Analysis) version 4.012, the engine design software tool currently in use. The project is assigned to juniors taking their first propulsion course in the aeronautical engineering major at the USAF Academy. This course, Aeronautical Engineering 361, which focuses on cycle analysis and selection, is required of all aero majors and is used to satisfy the ABET Program Criterion requiring knowledge of propulsion fundamentals. This paper describes the most recent design project that required the students to re-engine the USAF T-38 with the aim of competing for the Advanced Pilot Training Program (T-X) program. The goal of the T-X program is to replace the T-38 aircraft that entered service in 1961 with an aircraft capable of sustained high-G operations that is also more fuel efficient. The design project required the students to select an engine-cycle for a single, non-afterburning, mixed stream, low bypass turbofan engine to replace the two J85 turbojets currently in the T-38. It was anticipated that the high specific thrust requirements might possibly be met through the use of modern component measures of merit to include a much higher turbine inlet temperature. Additionally, it was anticipated that the required 10% reduction in thrust specific fuel consumption might possibly be achieved by using a turbofan engine cycle with a higher overall pressure ratio. This paper will describe the use of GasTurb 12 to perform the same design analysis that was described above using AEDsys as well as additional features such as numerical optimization, temperature-entropy diagrams, and the generation of scaled, two-dimensional engine geometry drawings. The paper will illustrate how GasTurb 12 offers important supplementary information that will deepen student understanding of engine cycle design and analysis.

Computational Aid to AEDsys for Designing a Variable-Area Gas Turbine Nozzle

2018 ◽  
Author(s):  
Devin O. O’Dowd ◽  
Aaron R. Byerley
Keyword(s):  
Gas Turbine ◽  
United States Air Force ◽  
System Analysis ◽  
Graphical Representation ◽  
Aircraft Engine ◽  
The United States ◽  
Design System ◽  
Engine Design ◽  
Critical Feedback ◽  
Gas Turbine Nozzle

This paper presents a practical approach to designing a gas turbine nozzle with the help of the Aircraft Engine Design textbook as well as the software program Nozzle, a subprogram within the Aircraft Engine Design System Analysis Software suite AEDsys. The current textbook and software allow for a variable wetted length of the converging and diverging nozzle sections. Critical feedback from industry experts has inspired an attempt to design a nozzle with fixed wetted material lengths. This paper is written to augment classroom treatment, but will also support others who use the Aircraft Engine Design text and software for a preliminary engine design capstone. This approach is further guided by the actual scaling of the Pratt & Whitney F100 variable geometry converging-diverging nozzle, where wetted lengths are fixed. The chief goal is to equip students at the United States Air Force Academy with a refined approach that is more realistic of a manufactured nozzle design, producing a graphical representation of a nozzle schedule at different speed and altitude flight conditions, both with and without afterburner.

Oil Pumping in High Speed and High Loaded Ball Bearings

2004 ◽  
Author(s):  
Michael Flouros
Keyword(s):  
High Speed ◽  
Ball Bearing ◽  
Research Programme ◽  
Aircraft Engine ◽  
Ball Bearings ◽  
European Research ◽  
Rolling Bearings ◽  
Engine Design ◽  
Oil Flow ◽  
Total Oil

Trends in aircraft engine design cause increased mechanical stress requirements for rolling bearings. Consequently high amounts of heat are rejected which results in high oil scavenge temperatures. The direction of oil flow in the bearing can considerably affect the heat transported by the oil. An RB199 turbofan bearing and its associated chamber were modified to carry out the survey. The test bearing was a 124mm PCD ball bearing. The bearing has a split inner-ring employing under-race lubrication by two individual jets. The total oil flow could be devided to any ratio through the jets. This had an impact on the oil scavenge temperatures and the scavenge flows on both sides of the bearing. Significant reduction in the ‘heat to oil’ was achieved when oil was fed at certain proportions (ratio). This work is part of the European Research programme Brite Euram ATOS (Advanced Transmission and Oil Systems).

Nozzle dimension design for aircraft engine infrared signature and thrust active control using MOEA/D

2020 ◽  
Vol 234 (15) ◽  
pp. 2133-2138
Author(s):  
Yu Zhao ◽  
Shijie Zheng
Keyword(s):  
Nozzle Exit ◽  
Infrared Radiation ◽  
Exhaust System ◽  
Aircraft Engine ◽  
Radiation Energy ◽  
Diameter Ratio ◽  
Rear Side ◽  
Military Aircraft ◽  
Infrared Signature ◽  
Aircraft Survivability

Aircraft infrared signature is one of the most important properties for the military aircraft survivability. In terms of military aircraft, the exhaust system is the most significant infrared radiation source. The exhaust system accounts for more than 90% of the aircraft infrared radiation, and that the exhaust nozzle contributes the most significant infrared radiation of the whole radiation energy provided by the exhaust system from the rear aspect. Low detectionable feature for military aircraft has attracted more importance to promote aircraft survivability via reducing infrared signature. The alteration of nozzle exit area affects an aircraft engine performance; meanwhile, it severely influences the engine infrared signature radiation from the rear side. The present paper is mainly focused on searching an appropriate group of nozzle exit diameter and throat to exit diameter ratio, which can reduce infrared signature radiation while cutting down the loss of thrust. Hence, objectives involve two aspects: one is minimum infrared signature level, and the other is minimum thrust loss. The multi-objective evolutionary algorithm based on decomposition has been employed to solve this bi-objective optimization problem. The optimization results illustrate that dimension selection range and throat to exit diameter ratio exert more important effect on the thrust loss and infrared signature level. Furthermore, the thrust plays significant role for deciding nozzle exit diameter and throat diameter.

Sign in / Sign up

Export Citation Format

Share Document