Development of an automated aircraft subsystem architecture generation and analysis tool

Purpose – The purpose of this paper is to present a new computational framework to address future preliminary design needs for aircraft subsystems. The ability to investigate multiple candidate technologies forming subsystem architectures is enabled with the provision of automated architecture generation, analysis and optimization. Main focus lies with a demonstration of the frameworks workings, as well as the optimizers performance with a typical form of application problem. Design/methodology/approach – The core aspects involve a functional decomposition, coupled with a synergistic mission performance analysis on the aircraft, architecture and component levels. This may be followed by a complete enumeration of architectures, combined with a user defined technology filtering and concept ranking procedure. In addition, a hybrid heuristic optimizer, based on ant systems optimization and a genetic algorithm, is employed to produce optimal architectures in both component composition and design parameters. The optimizer is tested on a generic architecture design problem combined with modified Griewank and parabolic functions for the continuous space. Findings – Insights from the generalized application problem show consistent rediscovery of the optimal architectures with the optimizer, as compared to a full problem enumeration. In addition multi-objective optimization reveals a Pareto front with differences in component composition as well as continuous parameters. Research limitations/implications – This paper demonstrates the frameworks application on a generalized test problem only. Further publication will consider real engineering design problems. Originality/value – The paper addresses the need for future conceptual design methods of complex systems to consider a mixed concept space of both discrete and continuous nature via automated methods

Experimental investigation into aircraft system manual assembly performance under varying structural component orientations

Installation of aircraft wing systems is a bottleneck in the assembly process. This phase is typically composed of many work packages, taking hundreds of man-hours per wing. In addition to this volume of work, tasks are specialized and completed in a difficult environment in terms of access and visibility. In current industrial practice, the wing is mounted horizontally on a transport trolley, which exposes the workforce to prolonged periods of overhead working. Future wing designs may consider a pre-equipping build philosophy, where systems are installed to major structure assemblies before the wing box is assembled. This allows for a change in the orientation and position of the major structure and provides new freedoms in assembly station design and layout. This research presents results of experiments to investigate manual assembly performance of aircraft wing systems, under varying wing structure orientation. A mock-up of a section of an A320 aircraft wing front spar, mounted on a rotation device, functions as the testbed. Manual installation activities are then conducted to emulate real aircraft system equipping for electric harnesses, raceways and hot air ducts. The results show a best-case assembly performance change of 36% for electric system installation activities of cable harnesses and raceway housing components. Tilted and horizontal orientations of the structure show the highest time reductions, with the vertical orientation either non-conclusive or increasing the assembly time. The outcomes of this study are intended to aid in effective trade-off decision making for future wing systems and assembly station layouts from the perspective of structural orientation and assembly task interaction

Application of an automated aircraft architecture generation and analysis tool to unmanned aerial vehicle subsystem design

The work presents the application of a new computational framework, addressing future preliminary design needs for aircraft subsystems. The ability to investigate multiple candidate technologies forming subsystem architectures is enabled with the provision of automated architecture generation, analysis and optimisation. The core aspects involve a functional decomposition, coupled with a synergistic mission performance analysis on the aircraft, architecture and component level. This may be followed by a complete enumeration of architectures combined with a user-defined technology filtering and concept ranking procedure. In addition, a novel hybrid heuristic optimiser, based on ant colony optimisation and a genetic algorithm, is employed to produce optimal architectures in both component composition and design parameters. The framework is applied to the design of a regenerative energy system for a long endurance high altitude unmanned aerial vehicle, considering various emerging technologies. A comparison with the traditional design processes and certification requirements is made as well as technology trends summarised and substantiated

Effects of more electric systems on fuel tank thermal behaviour

With the advent of more electric airframe systems and ultra-high bypass ratio turbofan engines, there is growing interest in the associated thermal implications. In this research project, an aircraft level model that is appropriate to enable investigations into novel thermal management solution on future aircraft is developed. In this paper, an investigation into the effects of more electric systems on the thermal behaviour of fuel tanks in civil transport aircraft is presented.Specifically, the influence of the heat generated by conventional and more electric systems on the fuel tank was modelled and simulated. A fuel thermal model was developed, which consists of a tank geometry representation, coupled to a module that calculates remaining mission fuel mass. The systems architectures are represented by connected thermal component models. Standard approaches were then employed to estimate convection and conduction heat transfer coefficients at the tank interfaces. The model solves 1-D transient heat equations, coupling heat transfer and material heat capacity via heat flux balances. The thermal and systems models were integrated into a baseline aircraft performance model, which was used to dynamically simulate the tank thermal behaviour during representative missions. The initial results indicate that switching to more electric environmental control and iceprotection systems likely have negligible thermal impact on the bulk fuel temperature. However, some benefits may be obtained regarding safety and certification, but this requires further study

Rotorcraft systems modelling for twin-engine heavy helicopter

The projected growth in air travel over the coming decades has been extensively documented in the open literature. Most of this growth comes from fixed wing aircraft travels, and therefore much research has been reported in this aircraft category. Much less documentation on the subject is available for the rotorcraft counterpart. Nevertheless, the environmental impact of rotorcraft should not be taken lightly. This research focuses on quantifying and reducing the negative environmental impact that rotorcraft operations have. This is achieved in particular by modelling the rotorcraft airframe systems and analyzing their environmental impact at mission level. This will be achieved by investigating the concept of a more-electric rotorcraft, in realizing the 'green rotorcraft' concept aspired to in the Clean Sky project. The Rotorcraft Mission Energy Management (RMEM) model is a tool developed which represents all of the secondary power generation and user systems on a rotorcraft. The RMEM simulates the onboard helicopter systems and determines, the shaft power and engine bleed air off-take requirements of each system for prescribed sets of flight conditions. For the purpose of demonstration, three generations of rotorcraft will be presented: the current, the near-term future and the medium-term future; with each generation having different levels of technology installed. A simulation of a mission case study will be presented which analyses the total shaft power off-take of each rotorcraft as a function of mission time

Framework for integrated dynamic thermal simulation of future civil transport aircraft

The development of increasingly more electric systems and ultra high bypass ratio turbofan engines for civil transport aircraft is projected to bring forth critical challenges regarding thermal management. To address these, it is required that the thermal behavior of the complete propulsion-airframe unit is studied in an integrated manner. To this purpose, a simulation framework for performing integrated thermal and performance analyses of the engines, airframe, and airframe systems, is presented. The framework was specifically devised to test novel integrated thermal management solutions for future civil aircraft. In this paper, the discussion focuses mainly on the thermal modeling of the wing and fuel. A highly flexible approach for creating wing thermal models by means of assembling generic thermal compartments is introduced. To demonstrate some of the capabilities, a case study is provided that involves thermal analysis of a single-aisle airplane with ultra high bypass ratio engines. Results are provided for fuel temperatures across flights in standard, hot, and cold days and for different airframe materials. Engine heat sink temperatures and input power to the engine gearboxes, both important parameters needed to design thermal management systems, are also presented

Rapid design of aircraft fuel quantity indication systems via multi-objective evolutionary algorithms

The design of electrical, mechanical and fluid systems on aircraft is becoming increasingly integrated with the aircraft structure definition process. An example is the aircraft fuel quantity indication (FQI) system, of which the design is strongly dependent on the tank geometry definition. Flexible FQI design methods are therefore desirable to swiftly assess system-level impact due to aircraft level changes. For this purpose, a genetic algorithm with a two-stage fitness assignment and FQI specific crossover procedure is proposed (FQI-GA). It can handle multiple measurement accuracy constraints, is coupled to a parametric definition of the wing tank geometry and is tested with two performance objectives. A range of crossover procedures of comparable node placement problems were tested for FQI-GA. Results show that the combinatorial nature of the probe architecture and accuracy constraints require a probe set selection mechanism before any crossover process. A case study, using approximated Airbus A320 requirements and tank geometry, is conducted and shows good agreement with the probe position results obtained with the FQI-GA. For the objectives of accessibility and probe mass, the Pareto front is linear, with little variation in mass. The case study confirms that the FQI-GA method can incorporate complex requirements and that designers can employ it to swiftly investigate FQI probe layouts and trade-offs

A generic mission-level flight control surface EMA power consumption simulation tool

The use of electromechanical actuators (EMAs) for aeronautical applications promises substantial benefits regarding efficiency and operability. To advance the design of power electronics and secondary power supply, there is a need for the ability to swiftly study the effects of aircraft mission and operational aspects on the actuator energy consumption. Pursuant to this, the aim of the work presented in this paper is twofold: (i) to build a generic mission-level flight control surface EMA power consumption simulation framework and (ii) to apply this framework to a case study involving a small all-electric aircraft, in which selected factors that impact energy consumption are investigated. The core of the framework comprises physics-based EMA power estimators, linked with a six-degree-of-freedom flight dynamics and control simulation module. The case study results show that the actuator power consumption correlates positively with the proportional gains in the flight control system but is inversely proportional to the trajectory radius and linearly dependent on turbulence intensity. The developed framework could aid in the selection of the actuator, as well as in the optimisation of airborne electronics and secondary power supply

Predicting cavitation erosion on two-stage pumps using CFD

Cavitation is a common problem that occurs in pumps which reduces its useful life and bring increased operating costs to the user. A study of cavitation erosion on a two-stage centrifugal pump has been carried out using Computational Fluid Dynamics (CFD). Most cavitation studies on pumps have been focused on modelling the severity of cavitation; specifically, on understanding its visual effects and performance penalties. Few works have been carried out to predict the most erosion-sensitive areas inside a pump. The focus of this study is on modelling the permanent damage that would be caused by cavitation and to identify specific areas within the pump which are most susceptible to erosion. The model is first validated against experimental data from another work. Once the simulation has been successfully calibrated, the cavitation simulation is carried out again with the subject pump. Not only does this work extend the findings previous works by predicting cavitation erosion on a two-stage pump, but the pump rotation speed is also varied to observe how the erosion-sensitive areas on the pump changes as a result. A specific focus on the Gray Level Method is carried out to predict the erosion damage on the pump. This technique is chosen as it has been experimentally proven with single-stage radial pumps, using specialized CFD code. It is found that the algorithm used to predict erosion when applied with commercial CFD packages, are useful in distinguishing areas inside the pump which are most vulnerable to erosion damage. The Scherr-Sauer cavitation model coupled with the κ-ω SST turbulence model have been used to run the cavitation simulations

Organization Theory in Business and Management History: Present Status and Future Prospects

Copyright © The President and Fellows of Harvard College 2017. A common lament is that business history has been marginalized within mainstream business and management research. We propose that the remedy lies in part with more extensive engagement with organization theory. We illustrate our argument by exploring the potentialities for business history of three cognitive frameworks: institutional entrepreneurship, evolutionary theory, and Bourdieusian social theory. Exhibiting a higher level of theoretical fluency might enable business historians to accrue scholarly capital within the business and management field by producing theoretically informed historical discourse, demonstrating the potential of business history to extend theory, generate constructs, and elucidate complexities in unfolding relationships, situations, and events