8,266 research outputs found
Optimal design of a composite wing structure for a flying-wing aircraft subject to multi-constraint
No full textThis thesis presents a research project and results of design and optimization of a composite wing structure for a large aircraft in flying wing configuration. The design process started from conceptual design and preliminary design, which includes initial sizing and stressing followed by numerical modelling and analysis of the wing structure. The research was then focused on the minimum weight optimization of the /composite wing structure /subject to multiple design /constraints. The modelling, analysis and optimization process has been performed by using the NASTRAN code. The methodology and technique not only make the modelling in high accuracy, but also keep the whole process within one commercial package for practical application.
The example aircraft, called FW-11, is a 250-seat commercial airliner of flying wing configuration designed through our MSc students Group Design Project (GDP) in Cranfield University. Started from conceptual design in the GDP, a high-aspect-ratio and large sweepback angle flying wing configuration has been adopted. During the GDP, the author was responsible for the structural layout design and material selection. Composite material has been chosen as the preferable material for both the inner and outer wing components. Based on the derivation of structural design data in the conceptual phase, the author continued with the preliminary design of the outer wing airframe and then focused on the optimization of the composite wing structure. Cont/d
Optimal design of a flying-wing aircraft inner wing structure configuration
No full textFlying-wing aircraft are considered to have great advantages and potentials in
aerodynamic performance and weight saving. However, they also have many
challenges in design. One of the biggest challenges is the structural design of
the inner wing (fuselage). Unlike the conventional fuselage of a tube
configuration, the flying-wing aircraft inner wing cross section is limited to a
noncircular shape, which is not structurally efficient to resist the internal
pressure load. In order to solve this problem, a number of configurations have
been proposed by other designers such as Multi Bubble Fuselage (MBF),
Vaulted Ribbed Shell (VLRS), Flat Ribbed Shell (FRS), Vaulted Shell
Honeycomb Core (VLHC), Flat Sandwich Shell Honeycomb Core (FLHC), Y
Braced Box Fuselage and the modified fuselage designed with Y brace
replaced by vaulted shell configurations. However all these configurations still
inevitably have structural weight penalty compared with optimal tube fuselage
layout. This current study intends to focus on finding an optimal configuration
with minimum structural weight penalty for a flying-wing concept in a preliminary
design stage.
A new possible inner wing configuration, in terms of aerodynamic shape and
structural layout, was proposed by the author, and it might be referred as
‘Wave-Section Configuration’. The methodologies of how to obtain a structurally
efficient curvature of the shape, as well as how to conduct the initial sizing were
incorporated.
A theoretical analysis of load transmission indicated that the Wave-Section
Configuration is feasible, and this was further proved as being practical by FE
analysis. Moreover, initial FE analysis and comparison of the Wave-Section
Configuration with two other typical configurations, Multi Bubble Fuselage and
Conventional Wing, suggested that the Wave-Section Configuration is an
optimal design in terms of weight saving. However, due to limitations of the
author’s research area, influences on aerodynamic performances have not yet
been taken into account
Influence of wing kinematics on aerodynamic performance in hovering insect flight
No full textThe influence of different wing kinematic models on the aerodynamic performance of a hovering insect is investigated by means of two-dimensional time-dependent Navier–Stokes simulations. For this, simplified models are compared with averaged representations of the hovering fruit fly wing kinematics. With increasing complexity, a harmonic model, a Robofly model and two more-realistic fruit fly models are considered, all dynamically scaled at Re = 110. To facilitate the comparison, the parameters of the models were selected such that their mean quasi-steady lift coefficients were matched. Details of the vortex dynamics, as well as the resulting lift and drag forces, were studied. The simulation results reveal that the fruit fly wing kinematics result in forces that differ significantly from those resulting from the simplified wing kinematic models. In addition, light is shed on the effect of different characteristic features of the insect wing motion. The angle of attack variation used by fruit flies increases aerodynamic performance, whereas the deviation is probably used for levelling the forces over the cycle.Aerospace Design, Integration and OperationsAerospace Engineerin
Study on the interspecific hybridization of pleurotus by protoplast fusion.
No full textby Lau Wing Chung.Thesis (Ph.D.)--Chinese University of Hong Kong, 1985Bibliography: leaves 209-23
The effects of taxation on direct foreign investment in China.
No full textby Lau Fung Wing Heidi.Thesis (M.B.A.)--Chinese University of Hong Kong, 1989.Bibliography: leaves 80-81
A study of joint ventures in the People's Republic of China.
No full textby Lau, Sin-Tong William, Leung Wing-Keung Albert.Thesis (M.B.A.)--Chinese University of Hong Kong, 1987.Bibliography: leaves 179-180
The computerisation of production information system on a microcomputer for a small electronics manufacturer : a feasibility study.
No full textby Lau Chiu-chung, Jimmy [and] Wong Chun-wing, Frank.Bibliography: leaf 123Thesis (M.B.A.)--Chinese University of Hong Kong, 198
Preliminary fuselage structural configuration of a flying-wing type airline
No full textThe flying-wing is a type of configuration which is a tailless airplane accommodating all of its parts within the outline of a single airfoil. Theoretically, it has the most aerodynamic efficiency. The fuel consumption can be more efficient than the existed conventional airliner. It seems that this configuration can achieve the above mentioned requirements.
According to these outstanding advantages, many aircraft companies did a great deal of projects on the flying-wing concept. However, the application was only for sport and military use; for airliner, none of them entered production.
FW-11 is a flying-wing configuration airliner which is a design cooperation between Cranfield University and Aviation Industry Corporation of China (AVIC). Aiming the spatial economic and environmental needs, this 200-seat airliner would attract attention from airline companies for cost saving and environmental protection.
Before start, this program is designated for a new generation commercial aircraft to compete with the existing same capability airliner, such as Airbus A320 and Boeing 767. As the first team of this program, the aim is to finish the conceptual design and prepare the relevant document for next two teams that will perform preliminary and detail design.
As a member of FW-11 program and as part of the GDP, the author has been through the four conceptual design stages: engine manufacturers, aircraft family issues, structure design and the establishment of 3-D CAD model.
The aim of IRP study is to focus on the initial fuselage design
Dynamic Distribution-Sensitive Point Location
No full textWe propose a dynamic data structure for the distribution-sensitive point location problem. Suppose that there is a fixed query distribution in ℝ², and we are given an oracle that can return in O(1) time the probability of a query point falling into a polygonal region of constant complexity. We can maintain a convex subdivision S with n vertices such that each query is answered in O(OPT) expected time, where OPT is the minimum expected time of the best linear decision tree for point location in S. The space and construction time are O(n log² n). An update of S as a mixed sequence of k edge insertions and deletions takes O(k log⁵ n) amortized time. As a corollary, the randomized incremental construction of the Voronoi diagram of n sites can be performed in O(n log⁵ n) expected time so that, during the incremental construction, a nearest neighbor query at any time can be answered optimally with respect to the intermediate Voronoi diagram at that time
Adaptive Planar Point Location
No full textWe present a self-adjusting point location structure for convex subdivisions. Let n be the number of vertices in a convex subdivision S. Our structure for S uses O(n) space and processes any online query sequence sigma in O(n + OPT) time, where OPT is the minimum time required by any linear decision tree for answering point location queries in S to process sigma. The O(n + OPT) time bound includes the preprocessing time. Our result is a two-dimensional analog of the static optimality property of splay trees. For connected subdivisions, we achieve a processing time of O(|sigma| log log n + n + OPT)
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