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

Author(s):  
Devin O. O’Dowd ◽  
Aaron R. Byerley

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.

Author(s):  
August J. Rolling ◽  
Aaron R. Byerley ◽  
Charles F. Wisniewski

This paper is intended to serve as a template for incorporating technical management majors into a traditional engineering design course. In 2002, the Secretary of the Air Force encouraged the United States Air Force (USAF) Academy to initiate a new interdisciplinary academic major related to systems engineering. This direction was given in an effort to help meet the Air Force’s growing need for “systems” minded officers to manage the development and acquisition of its ever more complex weapons systems. The curriculum for the new systems engineering management (SEM) major is related to the “engineering of large, complex systems and the integration of the many subsystems that comprise the larger system” and differs in the level of technical content from the traditional engineering major. The program allows emphasis in specific cadet—selected engineering tracks with additional course work in human systems, operations research, and program management. Specifically, this paper documents how individual SEM majors have been integrated into aeronautical engineering design teams within a senior level capstone course to complete the preliminary design of a gas turbine engine. As the Aeronautical Engineering (AE) cadets performed the detailed engine design, the SEM cadets were responsible for tracking performance, cost, schedule, and technical risk. Internal and external student assessments indicate that this integration has been successful at exposing both the AE majors and the SEM majors to the benefits of “systems thinking” by giving all the opportunity to employ SE tools in the context of a realistic aircraft engine design project.


Author(s):  
Dimitrios Chatzianagnostou ◽  
Stephan Staudacher

Abstract Hecto pressure composite cycle engines with piston engines and piston compressors are potential alternatives to advanced gas turbine engines. The nondimensional groups limiting their design have been introduced and generally discussed in Part I [1]. Further discussion shows, that the ratio of effective power to piston surface characterizes the piston thermal surface load capability. The piston design and the piston cooling technology level limit its range of values. Reynolds number and the required ratio of advective to diffusive material transport limit the stroke-to-bore ratio. Torsional frequency sets a limit to crankshaft length and hence cylinder number. A rule based preliminary design system for composite cycle engines is presented. Its piston engine design part is validated against data of existing piston engines. It is used to explore the design space of piston components. The piston engine design space is limited by mechanical feasibility and the crankshaft overlap resulting in a minimum stroke-to-bore ratio. An empirical limitation on stroke-to-bore ratio is based on existing piston engine designs. It limits the design space further. Piston compressor design does not limit the piston engine design but is strongly linked to it. The preliminary design system is applied to a composite cycle engines of 22MW take-off shaft power, flying a 1000km mission. It features three 12-cylinder piston engines and three 20-cylinder piston compressors. Its specific fuel consumption and mission fuel burn are compared to an intercooled gas turbine with pressure gain combustion of similar technology readiness.


Author(s):  
Aaron R. Byerley ◽  
Kurt P. Rouser ◽  
Devin O. O’Dowd

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.


Author(s):  
August J. Rolling ◽  
Aaron R. Byerley ◽  
Charles F. Wisniewski

This paper is intended to serve as a template for incorporating technical management majors into a traditional engineering design course. In 2002, the Secretary of the Air Force encouraged the USAF Academy to initiate a new interdisciplinary academic major related to systems engineering. This direction was given in an effort to help meet the Air Force’s growing need for “systems” minded officers to manage the development and acquisition of its ever more complex weapons systems. The curriculum for the new systems engineering management (SEM) major is related to the “engineering of large, complex systems and the integration of the many subsystems that comprise the larger system” and differs in the level of technical content from the traditional engineering major. The program allows emphasis in specific cadet-selected engineering tracks with additional course work in human systems, operations research, and program management. Specifically, this paper documents how individual SEM majors have been integrated into aeronautical engineering design teams within a senior level capstone course to complete the preliminary design of a gas turbine engine. As the Aeronautical engineering (AE) cadets performed the detailed engine design, the SEM cadets were responsible for tracking performance, cost, schedule, and technical risk. Internal and external student assessments indicate that this integration has been successful at exposing both the AE majors and the SEM majors to the benefits of “systems thinking” by giving all the opportunity to employ SE tools in the context of a realistic aircraft engine design project.


Author(s):  
Aaron R. Byerley ◽  
August J. Rolling ◽  
Kenneth W. Van Treuren

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.


Author(s):  
R. E. Cutler ◽  
Esten W. Spears

The military and industry have long recognized the potential of the regenerative-cycle gas turbine. Only recently has the “state-of-the-art” in regenerators and other lightweight turbine-engine components made it feasible to apply regeneration to aircraft engines. In applying regeneration to the aircraft gas turbine certain unique engine-design problems are encountered, such as: (a) Configuration and arrangement of lightweight, high effectiveness regenerator; (b) combustion system with side entry air; (c) turbine cooling at high inlet temperatures; (d) compressor operating flexibility; (e) control system for optimum engine response and operational flexibility; (f) configuration and arrangement of propeller and reduction gear.


Author(s):  
А. Михайлов ◽  
A. Mikhaylov ◽  
В. Михайлов ◽  
V. Mikhailov ◽  
Д. Михайлов ◽  
...  

In the paper presented there is carried out an analysis of peculiarities in the operation of structural elements and subsystems of gas turbine engine (GTE). A GTE structural reliability is investigated which is defined at the stage of aircraft engine design. There are shown structural logistic formulae of aircraft engine reliability. In the work there is offered a general approach to the life increase of GTE structural elements on the basis of functionally-directed properties. Basic principles for the support of functionally-directed properties of the GTE element base are shown. The ways to ensure a specified rated or limit GTE life on the basis of functionally-directed properties of elements are shown.


Author(s):  
Matthew J. Driscoll ◽  
Peter P. Descar ◽  
Gerald B. Katz ◽  
Walter E. Coward

As a cost savings measure, aircraft engine users often have hot section components reconditioned and re-installed during engine rebuilds and overhauls. This paper discusses the United States Navy’s test program to determine the risk/reward potential of refurbishing LM2500 high pressure turbine (HPT) blades. In a parallel effort, various marinized HPT blade coatings will be tested and their performance evaluated. General Electric’s LM2500 gas turbine is the main propulsion engine aboard the US Navy’s newest surface combatants (FFG 7, DD 963, CG 47, AOE 6 and DDG 51 class ships).


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