Comparison of Piston Concept Design Solutions for Composite Cycle Engines Part II: Design Considerations

2021 ◽  
Author(s):  
Dimitrios Chatzianagnostou ◽  
Stephan Staudacher
Keyword(s):  
Gas Turbine ◽  
Design Space ◽  
Piston Compressor ◽  
Design System ◽  
Surface Load ◽  
Preliminary Design ◽  
Concept Design ◽  
Piston Engine ◽  
Engine Design ◽  
Cylinder Piston

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.

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.

The Architecture and Application of Preliminary Design Systems

2011 ◽  
Author(s):  
Fabian Donus ◽  
Stefan Bretschneider ◽  
Reinhold Schaber ◽  
Stephan Staudacher
Keyword(s):  
Conceptual Design ◽  
Design System ◽  
Target Market ◽  
Preliminary Design ◽  
Design Phase ◽  
Planning Phase ◽  
Conceptual Design Phase ◽  
Engine Design ◽  
Design Systems ◽  
Aero Engines

The development of every new aero-engine follows a specific process; a sequence of steps or activities which an enterprise employs to conceive, design and commercialize a product. Typically, it begins with the planning phase, where the technology developments and the market objectives are assessed; the output of the planning phase is the input to the conceptual design phase where the needs of the target market are then identified, and alternative product concepts are generated and evaluated, and one or more concepts are subsequently selected for further development based on the evaluation. For aero-engines, the main goal of this phase is therefore to find the optimum engine cycle for a specific set of boundary conditions. This is typically done by conducting parameter studies where every calculation point within the study characterizes one specific engine design. Initially these engines are represented as pure performance cycles. Subsequently, other disciplines, such as Aerodynamics, Mechanics, Weight, Cost and Noise are accounted for to reflect interdisciplinary dependencies. As there is only very little information known about the future engine at this early phase of development, the physical design algorithms used within the various discipline calculations must, by default, be of a simple nature. However, considering the influences among all disciplines, the prediction of the concept characteristics translates into a very challenging and time intensive exercise for the pre-designer. This is contradictory to the fact that there are time constraints within the conceptual design phase to provide the results. Since the early 1970’s, wide scale efforts have been made to develop tools which address the multidisciplinary design of aero-engines within this phase. These tools aim to automatically account for these interdisciplinary dependencies and to decrease the time used to provide the results. Interfaces which control the input and output between the various subprograms and automated checks of the calculation results decrease the possibility of user errors. However, the demands on the users of such tools are expected to even increase, as such systems can give the impression that the calculations are inherently performed correctly. The presented paper introduces MTU’s preliminary design system Modular Performance and Engine Design System (MOPEDS). The results of simple calculation examples conducted using MOPEDS show the influences of the various disciplines on the overall engine system and are used to explain the architecture of such complex design systems.

Design Space Exploration and Optimization of Conceptual Rotorcraft Powerplants

2015 ◽  
Author(s):  
Fakhre Ali ◽  
Konstantinos Tzanidakis ◽  
Ioannis Goulos ◽  
Vassilios Pachidis ◽  
Roberto d’Ippolito
Keyword(s):  
Gas Turbine ◽  
Design Space Exploration ◽  
Design Space ◽  
Space Exploration ◽  
Multidisciplinary Design ◽  
Gaseous Emissions ◽  
Trade Offs ◽  
Engine Design ◽  
Wide Range ◽  
Single Objective

This paper demonstrates the application of an integrated rotorcraft multidisciplinary design and optimisation framework, deployed for the purpose of preliminary design and assessment of optimum regenerative powerplant configurations for rotorcraft. The proposed approach comprises a wide-range of individual modelling theories applicable to rotorcraft flight dynamics, gas turbine engine performance and weight estimation as well as a novel physics-based stirred reactor model, for the rapid estimation of various gas turbine gaseous emissions. A Single-Objective Particle Swarm Optimizer is coupled with the aforementioned rotorcraft multidisciplinary design framework. The overall methodology is deployed for the design space exploration and optimisation of a reference multipurpose twin-engine light civil rotorcraft, modelled after the Bo105 helicopter, employing two Rolls Royce Allison 250-C20B turboshaft engines. Through the implementation of single-objective optimization, notionally based optimum regenerative engine design configurations are acquired in terms of engine weight, mission fuel burn and mission gaseous emissions inventory, at constant technology level. The acquired optimum engine configurations are subsequently deployed for the design of conceptual regenerative rotorcraft configurations, targeting improved mission fuel economy, enhanced payload range capability as well as improvements in the rotorcraft overall environmental footprint, while maintaining the required airworthiness requirements. The proposed approach essentially constitutes an enabler in terms of focusing the multidisciplinary design of conceptual rotorcraft powerplants to realistic, three-dimensional operations and towards the realization of their associated engine design trade-offs at mission level.

Actual Design Space Methodology for Preliminary Design Analysis of Switched Reluctance Machines

2021 ◽  
Vol 57 (1) ◽  
pp. 397-408
Author(s):  
Roberto Rocca ◽  
Fabio Giulii Capponi ◽  
Giulio De Donato ◽  
Savvas Papadopoulos ◽  
Federico Caricchi ◽  
...  
Keyword(s):  
Design Space ◽  
Design Analysis ◽  
Preliminary Design ◽  
Switched Reluctance ◽  
Switched Reluctance Machines ◽  
Actual Design

Method for calculating the sliding bearing of a piston engine and compressor

2021 ◽  
pp. 51-54
Author(s):  
Keyword(s):  
Piston Compressor ◽  
Piston Engine ◽  
Sliding Bearing ◽  
One Dimensional ◽  
Working Length ◽  
Bearing Load ◽  
Compressor Piston ◽  
Crankshaft Journal ◽  
Relative Eccentricity ◽  
Engine Friction

A one-dimensional model for calculating the sliding bearing of a piston engine and compressor is proposed. The results of approximation of the graphs by analytical dependences of the relative eccentricity on the bearing load coefficient for different values of the ratio of the working length of the bearing to the diameter of the crankshaft journal are presented in the form of exponential functions. Keywords: sliding bearing, heat balance, piston compressor, piston engine, friction [email protected]; [email protected]; [email protected]

scholarly journals A Low-Leakage Discontinuously-Rotating Regenerator Designed for a Motor-Vehicle Gas Turbine

1996 ◽  
Author(s):  
Andreas Carl Pfahnl ◽  
David Gordon Wilson
Keyword(s):  
Gas Turbine ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Motor Vehicle ◽  
Compressed Air ◽  
Preliminary Design ◽  
Low Leakage ◽  
Design Calculations

A novel regenerator sealing concept is reported that can potentially reduce net compressed-air regenerator-seal leakage in gas turbines to unprecedented levels — near 1% of the net flow, greatly increasing the cycle thermal efficiency. The concept involves primarily discontinuously rotating a disk-type regenerator and implementing clamping seals. This work explains the principle of operation with discussions on preliminary-design calculations based on its use in a conceptual automotive gas turbine (Pfahnl and Wilson, 1995). Detailed regenerator-leakage calculations illustrate the drastically improved leakage rates.

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