A numerical simulation has been carried out to investigate the effects of leading edge blowing upon heat alleviation on the surface of hypersonic vehicles. The initial phase of this work deals with the ability of the present CFD-based techniques to solve hypersonic flow field past blunt-nosed vehicles at hypersonic speeds. Towards this end, the authors selected three re-entry vehicles with published flow field data against which the present computed results could be measured. With increasing confidence on the numerical simulation techniques to accurately resolve the hypersonic flow, the boundary condition at the solid blunt surface was then equipped with the ability to blow the flow out of the solid boundary at a rate of at least 0.01–0.1 times the free stream (ρ∞u∞) mass flow rate. The numerical iterative procedure was then progressed until the flow at the surface matched this new ‘inviscid like’ boundary condition. The actual matching of the flow field at the ejection control surface was achieved by iterating the flow on the adjacent cells until the flow conformed to the conditions prescribed at the control surface. The conditions at the surface could be submitted as a ρ∞u∞ at the surface or could be equipped as a simple static pressure condition providing the desired flow rate. The comparison between the present engineering approach and the experimental data presented in this study demonstrate its ability to solve complex problems in hypersonic.

This paper investigates the impact of the wall-heating conditions on the heat transfer performance of a rotating channel with one side smooth and one side roughened by 45° inclined ribs. Previous experimental and numerical studies for single-ribbed wall-heated channels showed that rotation has a significant negative impact on heat transfer performance. In order to investigate this uncommon behaviour, RANS simulations were conducted under three different wall-heating conditions in the present study: ribbed wall heated, all walls heated and adiabatic conditions. Numerical results show that the presence of uneven wall-heating conditions has a negligible impact on the stationary case, but it has a large influence on rotational cases, in both, the heat transfer and the flow field. The underlying reason is that in rotating cases, uneven heating results in different buoyancy effects on the trailing and leading walls of the channel that alter the main flow velocity profile. As a consequence, also secondary flows and heat transfer performance are affected.

In this paper, an integrated approach to turbine overspeed analysis is presented, taking into account the secondary air system dynamics and mechanical friction in a turbine assembly following an unlocated high-pressure shaft failure. The axial load acting on the rotating turbine assembly is a governing parameter in terms of overspeed protection since it governs the level of mechanical friction which acts against the turbine acceleration due to gas torque. The axial load is dependent on both the force coming from secondary air system cavities surrounding the disc and the force on the rotor blades. It is highly affected by secondary air system dynamics because rotor movement modifies the geometry of seals and flow paths within the network. As a result, the primary parameters of interest in this study are the axial load on the turbine rotor, the friction torque between rotating and static structures and the axial position of the rotor.

Following an initial review of potential damage scenarios, several cases are run to establish the effect of each damage scenario and variable parameter within the model, with comparisons being made to a baseline case in which no interactions are modelled. This allows important aspects of the secondary air system to be identified in terms of overspeed prevention, as well as guidelines on design changes in current and future networks that will be beneficial for overspeed prevention.

Information regarding deformations in large and complex systems is necessary in the prediction of structural failures caused by un-natural flexural occurrences. Sensing systems which are used to predict shapes, in order to develop a global surface picture require high precision and lower time lag. In this work, a unique bio-inspired training mechanism for support vector regression is presented for shape sensing in structures mounted with Fiber Bragg Gratings. Experimental validation was carried out on a simply supported beam, loaded at different positions and an aircraft wing model for different types of bending. The resulting deflections at specified locations along the length of the beam and on both surfaces of the wing were interpreted from the wavelength shifts of the corresponding Fiber Bragg Gratings through the specially modified Support Vector Regression. The method has shown high accuracy, low computational requirements and enhanced prediction times. The proposed bio-inspired training method has also been compared with two conventional training methodologies.

A nonlinear station-keeping control method for a multi-vectored propeller airship under unknown wind field with thrust saturation is developed, which is composed of three modules: nonlinear model predictive controller (NMPC), disturbance observer (DOB) and tracking differentiator (TD). The nonlinear kinematics and dynamics models are introduced, and the wind effect is considered by the wind-induced aerodynamic force. Based on both models, an explicit NMPC is designed. Then a nonlinear DOB is introduced to estimate the wind disturbance. A TD, showing the relationship between the maximum propulsion force and the maximum flight acceleration, is proposed to handle the thrusts’ amplitude saturation. Stability analysis shows that the closed-loop system is globally asymptotically stable. Simulations for a multi-vectored propeller airship are conducted to demonstrate the robustness and effectiveness of the proposed method.

An electromechanical coupling model is established for the space-tethered combination (STC) under microgravity environment after target capture by the tethered robot system (TRS). A linearized dynamic model of the STC is put forward with its controllability and observability as a control system analyzed. A double closed-loop tension control strategy is proposed to mitigate the impact and suing longitudinal vibration caused by the velocity difference between the platform and target. Experiment setup is built on a ground-based flotation platform to investigate the impact of the STC. Results of simulation and experimental validation show that the proposed tension control strategy is responsive and rapid in tension tracking and effectively prevent impact.

The flatness of a six-degree-of-freedom (6DoF) aircraft model with conventional control surfaces – aileron, flap, rudder and elevator, along with thrust vectoring ability is established in this work. Trajectory optimisation of an aircraft can be cast as an inverse problem where the solution for control inputs that yield desired trajectories for certain states is sought. The solution to the inverse problems for certain systems is made tractable when they exhibit differential flatness. Flatness-based trajectory optimisation has a significant advantage over an equivalent collocation-based method in terms of computational efficiency and viability for real-time implementation. An application for the flatness of 6DoF aircraft is shown in the trajectory optimisation for dynamic soaring, and its connection with an equivalent 3DoF flatness-based implementation is also brought out. The results are compared with that from a collocation-based approach.

Aiming at three-dimensional (3D) terminal guidance problem, a novel guidance model is established in this paper, in which line-of-sight (LOS) range is treated as an independent variable, describing the relative motion between the vehicle and the target. The guidance model includes two differential equations that describe LOS’s pitch and yaw motions in which the pitch motion is separately decoupled. This model avoids the inaccuracy of simplified two-dimensional (2D) guidance model and the complexity of 3D coupled guidance model, which not only maintains the accuracy but also simplifies the guidance law design. The application of this guidance model is studied for optimal re-entry guidance law with impact angle constraint, which is presented in the form of normal overload. Compared with optimal guidance laws based on traditional guidance model, the proposed one based on novel guidance model is implemented with the LOS range instead of time-to-go, which avoids the problem of the time-to-go estimation of traditional optimal guidance laws. Finally, the correctness and validity of the guidance model and guidance law are verified by numerical simulation. The guidance model and guidance law proposed in this paper provide a new way for the design of terminal guidance.