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1 – 10 of over 1000Terry Ford and CEng MRAeS
THE way in which powerplant characteristics are matched to those of an aircraft and the degree to which such integration is desirable are topics which have occupied designers for…
Abstract
THE way in which powerplant characteristics are matched to those of an aircraft and the degree to which such integration is desirable are topics which have occupied designers for a considerable time. Development technologies influence these considerations and lead to a limited choice of powerplant locations. A recent Royal Aeronautical Society conference addressed these issues and made an introductory point of the fact that the ideal extent of integration for say, a subsonic transport, will be quite different to that appropriate to a V/STOL or stealth combat type.
Jesús Matesanz-García, Tommaso Piovesan and David G. MacManus
Novel aircraft propulsion configurations require a greater integration of the propulsive system with the airframe. As a consequence of the closer integration of the propulsive…
Abstract
Purpose
Novel aircraft propulsion configurations require a greater integration of the propulsive system with the airframe. As a consequence of the closer integration of the propulsive system, higher levels of flow distortion at the fan face are expected. This distortion will propagate through the fan and penalize the system performance. This will also modify the exhaust design requirements. This paper aims to propose a methodology for the aerodynamic optimization of the exhaust for novel embedded propulsive systems. To model the distortion transfer, a low order throughflow fan model is included.
Design/methodology/approach
As the case study a 2D axisymmetric aft-mounted annular boundary layer ingestion (BLI) propulsor is used. An automated computational fluid dynamics approach is applied with a parametric definition of the design space. A throughflow body force model for the fan is implemented and validated for 2D axisymmetric and 3D flows. A multi-objective optimization based on evolutionary algorithms is used for the exhaust design.
Findings
By the application of the optimization methodology, a maximum benefit of approximately 0.32% of the total aircraft required thrust was observed by the application of compact exhaust designs. Furthermore, for the embedded system, it is observed that the design of the compact exhaust and the nacelle afterbody have a considerable impact on the aerodynamic performance.
Originality/value
This paper presents a novel approach for the exhaust design of embedded propulsive systems in novel aircraft configurations. To the best of the authors’ knowledge, this is the first detailed optimization of the exhaust system on an annular aft-mounted BLI propulsor.
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P. Laskaridis, V. Pachidis and P. Pilidis
The performance benefits of boundary layer ingestion (BLI) in the case of air vehicles powered by distributed propulsors have been documented and explored extensively by numerous…
Abstract
Purpose
The performance benefits of boundary layer ingestion (BLI) in the case of air vehicles powered by distributed propulsors have been documented and explored extensively by numerous studies. Therefore, it is well known that increased inlet flow distortion due to BLI can dramatically reduce these benefits. In this context, a methodology that enables the assessment of different propulsion architectures, whilst accounting for these aerodynamic integration issues, is studied in this paper.
Design/methodology/approach
To calculate the effects of BLI-induced distortion, parametric and parallel compressor approaches have been implemented into the propulsion system analysis. The propulsion architectures study introduces the concept of thrust split between propulsors and main engines and also examines an alternative propulsor configuration. In the system analysis, optimum configurations are defined using thrust-specific fuel consumption as figure of merit.
Findings
For determined operating conditions, the system analysis found an optimum configuration for 65 per cent of thrust delivered by the propulsor array, which was attributed mainly to the influence of the propulsor’s intake losses. An alternative propulsor design, which used the ejector pump effect to re-energize the boundary layer, and avoiding the detrimental effects of BLI are also cited in this work.
Originality/value
To summarize, this paper contributes with a general review of the research that has been undertaken to tackle the aforementioned aerodynamic integration issues and, in this way, make viable the implementation of distributed propulsion systems with BLI.
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The high probability of the occurrence of separation bubbles or shocks and early transition to turbulence on surfaces of airfoil makes it very difficult to design high-lift and…
Abstract
Purpose
The high probability of the occurrence of separation bubbles or shocks and early transition to turbulence on surfaces of airfoil makes it very difficult to design high-lift and high-speed Natural-Laminar-Flow (NLF) airfoil for high-altitude long-endurance unmanned air vehicles. To resolve this issue, a framework of uncertainty-based design optimization (UBDO) is developed based on an adjusted polynomial chaos expansion (PCE) method.
Design/methodology/approach
The γ ̄Re-θt transition model combined with the shear stress transport k-ω turbulence model is used to predict the laminar-turbulent transition. The particle swarm optimization algorithm and PCE are integrated to search for the optimal NLF airfoil. Using proposed UBDO framework, the aforementioned problem has been regularized to achieve the optimal airfoil with a tradeoff of aerodynamic performances under fully turbulent and free transition conditions. The tradeoff is to make sure its good performance when early transition to turbulence on surfaces of NLF airfoil happens.
Findings
The results indicate that UBDO of NLF airfoil considering Mach number and lift coefficient uncertainty under free transition condition shows a significant deterioration when complicated flight conditions lead to early transition to turbulence. Meanwhile, UBDO of NLF airfoil with a tradeoff of performances under both fully turbulent and free transition conditions holds robust and reliable aerodynamic performance under complicated flight conditions.
Originality/value
In this work, the authors build an effective uncertainty-based design framework based on an adjusted PCE method and apply the framework to design two high-performance NLF airfoils. One of the two NLF airfoils considers Mach number and lift coefficient uncertainty under free transition condition, and the other considers uncertainties both under fully turbulent and free transition conditions. The results show that robust design of NLF airfoil should simultaneously consider Mach number, lift coefficient (angle of attack) and transition location uncertainty.
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L. Djayapertapa and C.B. Allen
Transonic flutter and active flap control, in two dimensions, are simulated by coupling independent structural dynamic and inviscid aerodynamic models, in the time domain. A…
Abstract
Transonic flutter and active flap control, in two dimensions, are simulated by coupling independent structural dynamic and inviscid aerodynamic models, in the time domain. A flight control system, to actively control the trailing edge flap motion, has also been incorporated and, since this requires perfect synchronisation of fluid, structure and control signal, the “strong” coupling approach is adopted. The computational method developed is used to perform transonic aeroelastic and aeroservoelastic calculations in the time domain, and used to compute stability (flutter) boundaries of 2D wing sections. Open and closed loop simulations show that active control can successfully suppress flutter and results in a significant increase in the allowable speed index in the transonic regime. It is also shown that active control is still effective when there is free‐play in the control surface hinge. Flowfield analysis is used to investigate the nature of flutter and active control, and the fundamental importance of shock wave motion in the vicinity of the flap is demonstrated.
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Arne Seitz, Julian Bijewitz, Sascha Kaiser and Guido Wortmann
The purpose of this paper is the multi-disciplinary conceptual investigation of a propulsive fuselage (PF) aircraft layout allowing for new performance synergies through closely…
Abstract
Purpose
The purpose of this paper is the multi-disciplinary conceptual investigation of a propulsive fuselage (PF) aircraft layout allowing for new performance synergies through closely coupled propulsion/airframe integration. The discussed aircraft layout facilitates the ingestion of the fuselage boundary layer and the utilization of wake filling, thus eliminating a significant share of fuselage drag.
Design/methodology/approach
Based on consistent book-keeping standards for conventionally installed and highly integrated propulsion systems, key aspects of conceptualisation regarding airframe and propulsion system are presented. As a result of this, a PF aircraft configuration is proposed featuring a fuselage fan power plant in conjunction with two under-wing podded power plants. Parametric models for integrated aircraft and propulsion system sizing and performance analysis are discussed that are suitable for the consistent mapping of the characteristics intrinsic to a PF layout. In an initial benchmarking exercise, the vehicular efficiency potentials of the previously identified PF configuration are evaluated against an advanced conventional reference aircraft.
Findings
During benchmarking, it was found that a best and balanced design for the proposed PF aircraft layout yields an increase in vehicular efficiency of approximately 10 per cent compared to the advanced conventional reference aircraft.
Practical implications
The paper gives the reader an idea for the efficiency potentials achievable through a PF aircraft configuration, as well as guidelines for aircraft sizing and integrational aspects. It may serve as a basis for advanced studies in the future.
Originality/value
The conceptual investigation of the PF concept idea, contributes to establishing the initial technical feasibility of this novel approach to synergistic propulsion system integration. The methods presented in this paper allow for the multi-disciplinary conceptual design sizing of a PF aircraft.
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Thomas Frädrich, Julia Pachow‐Frauenhofer, Fiege Torsten and Peter Nyhuis
The purpose of this paper is to transfer the idea of changeability to a concrete technical application.
Abstract
Purpose
The purpose of this paper is to transfer the idea of changeability to a concrete technical application.
Design/methodology/approach
Based on the definition of changeability on a factory level, a transformation of the five change enablers specified therein for the work station level using the example of an aerodynamic feeding system takes place in this paper.
Findings
The observed aerodynamic feeding system can be determined as changeable.
Practical implications
Changeable systems are able to react with low effort to exterior influences, e.g. of the market, and thus represent a considerable competitive advantage.
Originality/value
The new element in this paper is the observation of change enablers on the work station level. This point of view enables the concrete figuration of changeable technical systems.
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Abstract
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IT is commonly held that today we are living in the age of the specialist. Within the aircraft industry, no one is more vulnerable to having this label of specialist thrust upon…
Abstract
IT is commonly held that today we are living in the age of the specialist. Within the aircraft industry, no one is more vulnerable to having this label of specialist thrust upon him than the flutter and vibration engineer, but I submit that far from having the narrow outlook which is taken to be the specialist's chief property, the flutter man has to be part stressman and part aerodynamicist; he must also have a working knowledge of the application of electronics to modern vibration test techniques and computing machinery, to say nothing of being part mathematician and, not least, part engineer, for we must not forget that after all, strange as it may seem at times to some of us, in the calm of our design offices, we are engaged in the engineering business.
The purpose of this paper is to explore the possibilities of introducing a number of visionary and pioneering ideas and upcoming enabling technologies for a conceptual and…
Abstract
Purpose
The purpose of this paper is to explore the possibilities of introducing a number of visionary and pioneering ideas and upcoming enabling technologies for a conceptual and aerodynamic design of green business jet aircraft to meet various requirements within Green and N + 2 Aircraft framework, and at the same time, to meet the requirements of air transportation demand, economic growth and environmental conservation.
Design/methodology/approach
A synthesis of various aircraft design methodologies has been carried out through iterative optimization to arrive at the conceptually designed aircraft with novel concept with optimum performance within the subsonic flight regimes. Major ideas derived from D8 and other novel concepts are appropriately applied in the work, which starts with fuel efficient motivation, and followed by wing aerodynamics and other critical factors related to the design requirements and objectives.
Findings
Through a meticulous effort following the synthesized design methodologies in the conceptual design phase, a conceptual design of a quad-bubble business jets with a set of specifications that meet the green and N + 2 aircraft technology requirements and exhibit promising performances is proposed and assessed within recent aircraft technology development.
Research limitations/implications
The research work is limited to conceptual design and analytical work which should be followed by further iterative steps incorporating experiments and detailed structural and aerodynamic computations.
Practical implications
The conceptual design proposed can be utilized as a baseline for further practical step in an aircraft development project.
Social implications
The conceptual design proposed could be utilized for business and economic study for future air transportation system.
Originality/value
The work is original, incorporating review of state-of-the-art technology, environmental requirements and a synthesis of a novel product.
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