This study is focused on the development of longitudinal aerodynamic models for steady flight conditions. While several commercial solvers are available for this type of work, we seek to evaluate the accuracy of an open source software. This study aims to verify and demonstrate the accuracy of the OpenFoam solver when it is used on basic computers (32–64GB of RAM and eight cores). A new methodology was developed to show how an aerodynamic model of an aircraft could be designed using OpenFoam software. The mesh and the simulations were designed only using OpenFoam utilities, such as blockMesh, snappyHexMesh, simpleFoam and rhoSimpleFoam. For the methodology illustration, the process was applied to the Bombardier CRJ700 aircraft and simulations were performed for its flight envelope, up to M0.79. Forces and moments obtained with the OpenFoam model were compared with an accurate flight data source (level D flight simulator). Excellent results in data agreement were obtained with a maximum absolute error of 0.0026 for the drag coefficient, thus validating a high-fidelity aerodynamic model for the Bombardier CRJ-700 aircraft.

Reinforced cables are usually installed on flexible airship structures to enhance their load-bearing capability. However, reinforced cables also increase the total weight of the airship. In order to find a balance between large loading-bear capability and light weight, a multi-objective optimisation scheme based on the genetic algorithm NSGA-II is put forward for the reinforced cable distribution on the airship. Firstly, different cable distribution schemes are presented according to engineering experience and the optimal one is determined by load analysis. Then, the CAE method and optimisation analysis are combined to achieve structure design optimisation. The parametric model of the airship structure with reinforced cables is established by ABAQUS secondary development and the load analysis is carried out. Parameter passing and optimisation algorithm are operated by Isight software and the optimisation analysis is conducted based on the NSGA-II algorithm. Finally, we draw some conclusions of the rules of optimised reinforcing cable distribution. The work of this paper has crucial engineering significance for improving performance of the airship structure design.

Hypersonic aerothermodynamics for a re-entry vehicle approaching the earth’s atmosphere is critical in the exploration of space. These vehicles often encounter various flow regimes due to the density variations and have surface abnormalities. The backward-facing step (BFS) is one such simplified configuration for modeling anomalies around such space vehicles. The present work examines rarefied hypersonic flow over a BFS using the direct simulation Monte Carlo (DSMC) method. The purpose of this research is focused on exploring the various loads encountered by a re-entry vehicle passing through different altitudes covering different rarefaction regimes. The fluid considered was non-reacting air, with the free-stream Mach number as 25, and the Knudsen number considered ranged from 0.05-21.10. The influence of the Knudsen number on flow characteristics has been elucidated graphically in various streamwise directions. The normalised flow properties such as velocity, pressure, temperature and density showed an increasing trend with the Knudsen number due to compressibility and viscous heating effects. In all flow regimes, there was an appearance of flow recirculation. With rarefaction, the recirculation lengths decreased, whereas the boundary layer thickness showed an increase. The aerodynamic surface properties such as pressure coefficient, skin friction, and heat transfer coefficient, by and large, showed an increase with the Knudsen number. When the chemical reactions were accounted for and compared against the non-reacting flows, the velocity, pressure, and density field showed no marked variation; however, considerable variations were observed in the temperature field. Furthermore, the present study also depicts the compressibility factor contour, showing the flow regions that diverge from the ideal gas behaviour.

Design success mostly depends on understanding and realising product requirements, which are nested with different levels of stakeholders and specific market demands. Emerging markets are volatile and non-linear for understanding user-specific needs, particularly related to aircraft design. We attempt herein to elicit specific requirements through a proposed requirements elicitation process based on functional, physical and behavioural viewpoints. An evaluation of those critical requirements is also performed through Quality Function Deployment (QFD) to reveal the fitness of the customer requirements (raw requirements) in relation to the technical measures. After selecting all projected potential users, a Systems Modelling Language (SysML) use-case diagram is also summarised to illustrate the user’s relation to the system functions. Some raw requirements are verified through constraint analysis and cost examination as an exemplary approach to present the transformation from raw to final requirements. The data are collected and analysed to construct the aircraft’s key specifications. Most importantly, how to identify good requirements that define the needs, attainability, clarity and verifiability is demonstrated.

In addition, it is demonstrated through this study that there is a need of a specific type of general aviation aircraft that may fulfil the unique demands of emerging economies by satisfying their socio-economic conditions.

A new method for predicting manoeuvre loads on a large transport aircraft with a swept-back wing and a load alleviation system based on control surface deflections is developed. For this purpose, three-dimensional Reynolds-averaged Navier–Stokes (RANS) simulations of the rigid wing–fuselage configuration are performed while the aerodynamics of the tailplane are estimated by means of handbook methods. For a closer analysis, different quasi-steady pitching manoeuvres are chosen based on the CS-25 regulations. One of these manoeuvres is also simulated with active load alleviation, leading to a reduction in the wing-root bending moment by more than 40%. Besides demonstrating the potential of the considered load alleviation system, it is shown which manoeuvres are especially critical in this context and which secondary effects come along with load alleviation.

This study focuses on vibration reduction for quadcopters and octocopters with elastic, two-bladed, fixed-speed, variable-pitch rotors through the use of relative rotor phasing. The study defines phase modes such as a pitch phase mode with relative phasing between the front and aft rotors, a roll phase mode with relative phasing between the left and right rotors, and a differential phase mode with relative phasing between the clockwise and counter-clockwise spinning rotors for both the quadcopter and the octocopter, as well as additional higher harmonic phase modes for the octocopter. Parametric studies on individual phase modes indicate that, for the quadcopter in forward flight, the pitch and roll phase modes can almost entirely eliminate the 2/rev vibratory forces (at the aircraft level), but the 2/rev vibratory moments cannot be minimised at the same time. By simultaneously using multiple phase modes, a Pareto front can be generated and a solution selected based on the relative emphasis on force or moment vibration reduction. For the octocopter, it was observed that individual higher harmonic modes (specifically the 2c or 2s modes) could almost entirely eliminate both the 2/rev vibratory forces and moments, simultaneously. Compared with vibration levels in forward flight that might, on average, be expected if the rotors were randomly phased, a 62% reduction of a composite vibration index can be achieved on a quadcopter, and complete elimination of vibration was achievable on an octocopter, with appropriate rotor phasing.

The German research Cluster of Excellence SE2A (Sustainable and Energy Efficient Aviation) is investigating different technologies to be implemented in the following decades, to achieve more efficient air transportation. This paper studies the Hybrid Laminar Flow Control (HLFC) using boundary layer suction for drag reduction, combined with other technologies for load and structural weight reduction and a novel full-electric propulsion system. A multidisciplinary design optimisation framework is presented, enabling physics-based analysis and optimisation of a fully electric aircraft wing equipped with HLFC technologies and load alleviation, and new structures and materials. The main focus is on simulation and optimisation of the boundary layer suction and its influence on wing design and optimisation. A quasi three-dimensional aerodynamic analysis is used for drag estimation of the wing. The tool executes the aerofoil analysis using XFOILSUC, which provides accurate drag estimation through boundary layer suction. The optimisation is based on a genetic algorithm for maximum take-off weight (MTOW) minimisation. The optimisation results show that the active flow control applied on the optimised geometry results in more than 45% reduction in aircraft drag coefficient, compared to the same geometry without HLFC technology. The power absorbed for the HLFC suction system implies a battery mass variation lower than 2%, considering the designed range as top-level requirement (TLR).