Functional modelling of complex multi‑disciplinary systems using the enhanced sequence diagram

YesThis paper introduces an Enhanced Sequence Diagram (ESD) as the basis for a structured framework for the functional analysis of complex multidisciplinary systems. The ESD extends the conventional sequence diagrams (SD) by introducing a rigorous functional flow-based modelling schemata to provide an enhanced basis for model-based functional requirements and architecture analysis in the early systems design stages. The proposed ESD heuristics include the representation of transactional and transformative functions required to deliver the use case sequence, and fork and join nodes to facilitate analysis of combining and bifurcating operations on flows. A case study of a personal mobility device is used to illustrate the deployment of the ESD methodology in relation to three common product development scenarios: (i) reverse engineering, (ii) the introduction of a specific technology to an existent system; and (iii) the introduction of a new feature as user-centric innovation for an existing system, at a logical design level, without reference to any solution. The case study analysis provides further insights into the effectiveness of the ESD to support function modelling and functional requirements capture, and architecture development. The significance of this paper is that it establishes a rigorous ESD-based functional analysis methodology to guide the practitioner with its deployment, facilitating its impact to both the engineering design and systems engineering communities, as well as the design practice in the industry

Functional modelling of complex multi‑disciplinary systems using the enhanced sequence diagram

YesThis paper introduces an Enhanced Sequence Diagram (ESD) as the basis for a structured framework for the functional analysis of complex multidisciplinary systems. The ESD extends the conventional sequence diagrams (SD) by introducing a rigorous functional flow-based modelling schemata to provide an enhanced basis for model-based functional requirements and architecture analysis in the early systems design stages. The proposed ESD heuristics include the representation of transactional and transformative functions required to deliver the use case sequence, and fork and join nodes to facilitate analysis of combining and bifurcating operations on flows. A case study of a personal mobility device is used to illustrate the deployment of the ESD methodology in relation to three common product development scenarios: (i) reverse engineering, (ii) the introduction of a specific technology to an existent system; and (iii) the introduction of a new feature as user-centric innovation for an existing system, at a logical design level, without reference to any solution. The case study analysis provides further insights into the effectiveness of the ESD to support function modelling and functional requirements capture, and architecture development. The significance of this paper is that it establishes a rigorous ESD-based functional analysis methodology to guide the practitioner with its deployment, facilitating its impact to both the engineering design and systems engineering communities, as well as the design practice in the industry

Experimental Investigations of Buffet Excitation Forces on a Low Aspect Ratio Trapezoidal Half Wing in Incompressible Flow.

The paper addresses the problem of determining the steady and unsteady airloads on swept wings of low aspect ratios at high incidences. Despite great progress in the field of computational fluid dynamics, this problem is not yet accessible to computer- supported methods, at least with respect to unsteady airloads. First, the information will be discussed which is necessary for buffeting prediction. The reason for performing pressure measurements are outlined. A brief description of the test set-up and instrumentation is given

Measurement of Unsteady Pressures and Forces on an Engine and a Wing/Engine Combination Including Jet Simulation.

Experimental investigations on the unsteady aerodynamic forces were performed on an ejector engine model and a wing/engine combination in the subsonic and transonic flow regimes. The experimental results were compared to theoretical results. The aim was to determine how well the commonly used mathematical aerodynamic models for flutter calculations correspond to the actual relationships observed on engines. The investigations on the ejector engine demonstrated that linear lifting surface theory provides accurate unsteady aerodynamic forces. The effects of Mach number and reduced frequency are described correctly. For the wing/engine combination, the unsteady interference effect for engine oscillation on the lower side of the wing is strongly influenced by flow separation at the wing/pylon connection. In general, the unsteady aerodynamic forces on the wing are small and, at this order of magnitude, can be correctly calculated with the linear lifting surface theory

Measurement of Steady and Unsteady Airloads on a Stiffness Scaled Model of a Modern Transport Aircraft Wing.

Extensive wind tunnel tests have been carried out on a modern transport aircraft wing in transonic flow. The objective was to measure steady and unsteady pressure distributions, and to investigate the influence of the variable twist distribution of an elastic wing. For this purpose the wind tunnel model was scaled in stiffness, so that the twist distribution was similar to a representative aircraft, and changed with loads variation. The extensive model instrumentation consisted of opto-electronical equipment to measure the actual wing twist distribution. The forced model oscillation in pitch and bending up to a reduced frequency of about 0,7 (based on a reference chord) was measured with conventional accelerometers. A piezo-electrical balance was used for steady and unsteady forces measurement. Steady and unsteady pressures were measured simultaneously with 290 pressure transducers. Investigated parameters were Mach number, stagnation pressure, angle of incidence, reduced frequency and oscillation amplitude

Measurement of Unsteady Airloads on an Oscillating Engine and a Wing-Engine Combination.

Experimental investigations of unsteady aerodynamic forces were performed on an oscillating ejector engine model and a wing/engine combination in the subsonic and transonic flow regimes. The experimental results were compared with theoretical results. The aim was to determine how well, in reality, the mathematical aerodynamic models commonly used for flutter calculations correspond to the flow conditions on an engine. The investigations on the isolated ejector engine demonstrated that linear lifting surface theory provides quite accurate unsteady aerodynamic forces. The effects of the Mach number and reduced frequency are described correctly. For the wing/engine combination, the unsteady interference effect of the engine oscillation on the lower side of the wing is strongly influenced by flow separation at the wing/pylon connection. In general, the unsteady aerodynamic forces induced by the engine on the wing are small and are therefore of minor influence on the unsteady airloads of an oscillating wing

Bestimmung instationaerer Triebwerksluftkraefte fuer die Anwendung bei Flatteruntersuchungen

Experimental and theoretical investigations into stationary and instationary aerodynamic forces were performed on an ejector power-unit model and on a wing power-unit model. The aim was to establish just how well the cylindrical through-flow pods, which are normally used as mathematical, aerodynamical models in flutter analyses, describe the actual situation in the power unit. The investigations on the ejector power unit have shown that the linear aerofoil procedures are a good reflection of the instationary aerodynamic forces. The influences of the Mach number and the reduced frequency are correctly described. In the case of the wing power-unit combination, the instationary interference effect from the power-unit oscillation on the wing is determined essentially by the flow separation at the wing pylon crossover. All in all, the aerodynamic forces at the wing are small and can be correctly calculated in this dimension by applying the linear aerofoil theory. The interference effects of the oscillating wing on the power unit, ascertained by means of quasi-stationary considerations, are considerably more significant. (orig.)Es wurden experimentelle und theoretische Untersuchungen der stationaeren und instationaeren Luftkraefte an einem Ejektortriebwerksmodell und an einer Fluegel-Triebswerkskomination durchgefuehrt. Das Ziel bestand darin, festzustellen, wie gut die ueblicherweise in Flatterrechungen als mathematische aerodynamische Modelle verwendeten zylindrischen Durchflussgondeln die wirklichen Verhaeltinsse am Triebwerk beschreiben. Die Untersuchungen am Ejektortriebwerk haben gezeigt, dass die linearen Tragflaechenverfahren die instationaeren Luftkraefte gut wiedergeben. Die Einfluesse von Machzahl und reduzierter Frequenz werden richtig beschrieben. An der Fluegel-Triebwerkskombination wird die instationaere Interferenzwirkung aus der Triebwerksschwingung am Fluegel wesentlich durch die Stroemungsabloesung am Fluegel-Pylonuebergang bestimmt. Insgesamt sind die instationaeren Luftkraefte am Fluegel klein und werden in dieser Groessenordnung richtig mit der linearen Tragflaechentheorie berechnet. Sehr viel deutlicher ist die Interferenzwirkung des schwingenden Fluegels auf das Triebwerk, die aus quasistationaeren Betrachtungen ermittelt wurde. (orig.)Available from TIB Hannover: RR 2061(27)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Verkehr, Bonn (Germany)DEGerman