scholarly journals Energy Based Functional Decomposition in Preliminary Design

2011 ◽  
Vol 133 (5) ◽  
Author(s):  
Jérôme Pailhès ◽  
Mohammed Sallaou ◽  
Jean-Pierre Nadeau ◽  
Georges M. Fadel
Keyword(s):  
Energy Flow ◽  
Reference State ◽  
Design System ◽  
Preliminary Design ◽  
Functional Decomposition ◽  
Simplified Approach ◽  
Energy Material ◽  
Energy Flows ◽  
Standard Energy ◽  
The Value Function

This paper presents an energy based approach to functional decomposition that is applicable to the top down design (system to subsystems to components) of mechanical systems. The paper shows that the main functions of convert and transmit are sufficient to focus on the “functional flow” or main energy flow resulting in the specific action sought as a result of the artifact being designed, and can be expanded upon at the lowest level when looking for specific solutions based upon the energy and mass balances and the knowledge within the design team. This approach considers function as a transformation and also fits the approach presented in TRIZ. The standard energy, material, and signal flows are seen as forms of energy flows, and it is only their transformation and transmission that is sought. This simplified approach, coupled with an aspect of control and interaction between a reference state and the artifact or between various components is sufficient to comprehensively describe the system that matches very nicely the value function approach of Miles. Furthermore, as these interactions can be considered as artifact-artifact affordances when considering the artifact for either artifact interaction or within an environment, its relation to the user and to the reference state can be addressed during the design phase, in addition to the functions.

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.

Statistical energy analysis as a tool for quantifying sound and vibration transmission paths

1994 ◽  
Vol 346 (1681) ◽  
pp. 449-464 ◽  
Keyword(s):  
Energy Flow ◽  
Complex Structure ◽  
Linear Equations ◽  
Least Square ◽  
Net Energy ◽  
Sea Temperature ◽  
Energy Flows ◽  
The Difference ◽  
Symmetry Relations ◽  
Loss Factors

When a complex structure is excited in several different ways by different sources, the sea energy balance equations result in a set of linear equations that can be used to calculate loss factors, coupling loss factors or net energy flows and incoming powers. If certain symmetry relations are used, and/or if some prior knowledge about the system is available, the set of linear equations is overdetermined and can be solved by a least square technique. A good indicator for the direction of the energy flow is the SEA temperature of the subsystems. Experiments and computer simulations performed on three plate arrangements gave in general good results when the coupling was weak and there were more than three modes in the frequency band of interest. Not so good results were obtained when a small energy flow has to be measured as the difference of large quantities.

Diffusion equation modelling for energy flow analysis in reverberation chambers

2021 ◽  
Vol 263 (1) ◽  
pp. 5637-5642
Author(s):  
Ryan Hao ◽  
Ning Xiang
Keyword(s):  
Diffusion Equation ◽  
Energy Flow ◽  
Flow Analysis ◽  
Equation Model ◽  
Computationally Efficient ◽  
Reverberation Chamber ◽  
Sound Fields ◽  
Energy Flows ◽  
Standardized Measurement ◽  
Reverberation Chambers

Noise is a growing concern in the built environment. Sound absorbers are a viable option for noise treatment. However, the characterization of their absorption coefficient in standardized measurement chambers still show challenges for high accuracy as required in practice. In recent years, experimental analysis has shown that assumptions of diffuse sound fields made in well-known reverberation chambers are unfulfilled. Specifically, that sound intensities in chamber-based measurement methods are presumed to be isotropic or diffuse. Diffusion equation models have shown dramatic changes in energy flow in the presence of highly absorptive materials under test. This has been attributed to well-documented inconsistencies reported from reverberation chamber measurements across different laboratories. This work will demonstrate that the diffusion equation model is proving to be a computationally efficient and viable method for predicting sound energy flows, garnering an increasing amount of interest from the acoustical community.

Predicting the Behavior of Solar Dynamic Closed Brayton Cycle Power Conversion Systems

1988 ◽  
Vol 110 (4) ◽  
pp. 636-640 ◽  
Author(s):  
R. Bons ◽  
J. Hanlon ◽  
S. Spencer
Keyword(s):  
Power Conversion ◽  
Space Station ◽  
Operating Conditions ◽  
System Model ◽  
Design System ◽  
Brayton Cycle ◽  
Preliminary Design ◽  
The Sun ◽  
Design Performance ◽  
Conversion System

Since space power conversion systems must operate both in the sun and in the earth’s shadow, they seldom encounter design operating conditions. As a consequence, consideration of off-design performance is essential in the preliminary design of these systems. To illustrate the necessity and utility of an off-design system model, this paper presents the results of a study of the solar dynamic closed Brayton cycle power conversion system for use on the NASA Space Station.

Energy Balance of Indian Villages: A Case Study of Seven Villages

2018 ◽  
Vol 1 (1) ◽  
pp. 77-103
Author(s):  
Amit Garg ◽  
Jaypalsinh Chauhan ◽  
Abha Chhabra ◽  
Tirthankar Nag
Keyword(s):  
Energy Balance ◽  
Energy Flow ◽  
Flow Model ◽  
Crop Yields ◽  
Gujarat State ◽  
Forest Density ◽  
Residential Sector ◽  
Energy Flows ◽  
Stock Change

This paper estimates the rural energy balance of 7 Indian villages of different agro-climate zones. This was done through primary survey of households in each village covering energy consumption, production, export, import and stock change across Crop, Livestock, Industry/Trade, Tree outside forest/plantations and Residential Sector. An energy flow model was created to capture all the various energy flows at household levels. Two villages are showing Negative annual energy balance—one is the desert village of Gujarat state and another is a tribal village of Mizoram state. All other villages were found to be energy positive mainly due to high forest density and high crop yields.

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.

Long-term Experiments on the Stability of Two Fish Populations in Previously Unexploited Arctic Lakes

1994 ◽  
Vol 51 (1) ◽  
pp. 209-225 ◽  
Author(s):  
Lionel Johnson
Keyword(s):  
Energy Flow ◽  
Environmental Variability ◽  
Salvelinus Alpinus ◽  
Stable State ◽  
Arctic Char ◽  
Arctic Lakes ◽  
System Stability ◽  
Fish Populations ◽  
Ecosystem Structure ◽  
Energy Flows

Previous research indicated that fish populations in arctic lakes maintain a constant size distribution and abundance in the face of the environmental variability experienced over their recent history. Such stability was tested over 15 seasons in Little Nauyuk and Gavia lakes (Northwest Territories) which contained previously undisturbed populations of Arctic char (Salvelinus alpinus). Initially, the length–frequency distribution of Arctic char in Little Nauyuk Lake was bell shaped, and in Gavia Lake, it could be described by a negative logarithmic expression. Initial sampling of Gavia Lake removed the largest fish, allowing a well-defined mode to develop (cf. Little Nauyuk Lake). In both lakes the modal value remained constant throughout the exploitation phase. When fishing ceased the populations returned to their original state without evident oscillation. The stable state of the dominant population is considered to be one of "least dissipation". It is hypothesized that ecosystem structure depends on countervailing forces, one tending to decelerate energy flow through the ecosystem and the second tending to accelerate it. For ecosystems to exist, the tendency to decelerate energy flow must dominate system behaviour over ecological time. An ecosystem is regarded as a hemeorhetic system, stability seeking through the stabilization of energy flows.

A Genetic Algorithm Based Preliminary Design System

1993 ◽  
Vol 207 (2) ◽  
pp. 127-133 ◽  
Author(s):  
D T Pham ◽  
Y Yang
Keyword(s):  
Genetic Algorithm ◽  
Design Stage ◽  
Design System ◽  
Prototype System ◽  
Preliminary Design ◽  
Design Concepts ◽  
Computer Aided ◽  
Preliminary Design Stage

The different stages in design are briefly discussed. Examples of previous research into automating the preliminary design stage are described. An architecture for a computer aided preliminary design system is proposed. A prototype system for generating design concepts for transmission devices is presented.

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