Dynamic Drag Reduction Effects of Aerospikes and Aerodisks

In order to investigate the dynamic characteristics of blunt aircraft mounted with aerospikes and aerodisks in large-amplitude force-pitching, the Roe spatial scheme and the lower-upper symmetric Gauss-Seidel (LU-SGS) method with dual time step are employed for discretization of unsteady Navier-Stokes (N-S) equations. A parametric investigation on the flow fields is conducted by altering the pitching period, aerospike length, and aerodisk diameter consequently via a variable-controlling procedure. Dynamic characteristics of aerodynamic drag as well as the visualization of unsteady flow fields are achieved, and the results show that the aerodynamics of hypersonic aircraft under the condition of large-amplitude force-pitching vibration have hysteresis characteristics affected by periods of force-pitching vibration. In addition, when changing aerospike length and aerodisk diameter, the variation tendency of drag reduction efficiency is determined by the pitching angle of the oscillation process.

L1 Adaptive Loss Fault Tolerance Control of Unmanned Hypersonic Aircraft with Elasticity

This paper investigates the fault tolerance control of hypersonic aircrafts with L1 adaptive control method in the presence of loss of actuator effectiveness fault. The hypersonic model considers the uncertainties caused by the features of nonlinearities and couplings. Elasticity is taken into account in hypersonic vehicle modeling which makes the model more accurate. A velocity L1 adaptive controller and an altitude L1 adaptive controller are designed to control flexible hypersonic vehicle model with actuator loss fault. A PID controller is designed as well for comparison. Finally, the simulation results are used to analyze the effectiveness of the controller. Compared to the results of PID controller, L1 controllers have better performance.

"THEORETICAL ASPECTS OF STRENGTH AND THERMAL CONTROL OF HYPERSONIC AIRCRAFT"

This article analyzes the theoretical aspects of controlling the strength and thermal modes of hypersonic aircraft. The conditions for the functioning of hypersonic aircraft were also investigated, and problematic situations for their design were identified. The parameters of aerodynamic heating of surfaces and heating of thermal protection of hypersonic aircraft were estimated with an assessment of the parameters of thermal protection of hypersonic aircraft and the magnitude of the heat flux supplied to the surface, with the determination of the parameters of their thermal protection, taking into account the thermophysical characteristics of materials from thermal parameters.

Simulation of Gas Dynamics of Hypersonic Aircrafts with the Use of Model of High-Temperature Air and Graphics Processor Units

Проводится численное моделирование обтекания гиперзвукового летательного аппарата с использованием модели высокотемпературного воздуха и гибридной архитектуры на основе высокопроизводительных графических процессорных устройств. Расчеты проводятся на основе уравнений Эйлера, для дискретизации которых применяется метод конечных объемов на неструктурированных сетках. Приводятся результаты исследования эффективности расчета гиперзвуковых течений газа на графических процессорах. Обсуждается время счета, достигнутое при использовании моделей совершенного и реального газа. Numerical simulation of the flow around a hypersonic aircraft is carried out using a high-temperature air model and a hybrid architecture based on high-performance graphics processing units. The calculations are performed with the Euler equations discretized by the finite volume method on unstructured meshes. The scalability of the developed implementations of the model is studied and the results of the study of the efficiency of calculating hypersonic gas flows on graphics processors are analyzed. The computational time spent with the perfect and real gas models is discussed.

A survey on the conceptual design of hypersonic aircraft powered by RBCC engine

Rocket-based combined-cycle (RBCC) powered vehicles have been widely recognized as the most promising aircraft solution that could dramatically reduce the cost of space transportation. Researchers and scientists worldwide have conducted considerable overall design researches to cope with the challenges in RBCC development including mode transition, thermal protection and thrust enhancement. According to the way to orbit and the configuration characteristics, the hypersonic aircraft powered by RBCC engine are classified as four categories: single-stage-to-orbit (SSTO) two-dimensional configuration, SSTO axisymmetric configuration, two-stage-to-orbit (TSTO) two-dimensional configuration, and TSTO axisymmetric configuration. This paper systematically presents the development of the conceptual design of RBCC-powered vehicles. Both the structural and operating key parameters like the weight distribution, the RBCC propulsion performance and take-off mode, et al. are introduced in detail. On this basis, a comparative analysis of the advantages and disadvantages of the orbit model, the configuration selection and takeoff modes are conducted. In addition, the application prospect and technology development direction for hypersonic aircraft are also discussed. At the same time, the lessons that can be drew from previous hypersonic vehicle concept design are explored.

Aerodynamic Study of the NASA’s X-43A Hypersonic Aircraft

A 2D aerodynamic study of the NASA’s X-43A hypersonic aircraft is developed using two different approaches. The first one is analytical and based on the resolution of the oblique shock wave and Prandtl–Meyer expansion wave theories supported by an in-house program and considering a simplified aircraft’s design. The second approach involves the use of a Computational Fluid Dynamics (CFD) package, OpenFOAM and the real shape of the aircraft. The aerodynamic characteristics defined as the lift and drag coefficients, the aerodynamic efficiency and the pitching moment coefficient are calculated for different angles of attack. Evaluations are made for an incident Mach number of 7 and an altitude of 30 km. For both methodologies, the required angles of attack to achieve a Vertical Force Balance (VFB) and a completely zero pitching moment conditions are considered. In addition, an analysis to optimise the nose configuration of the aircraft is performed. The mass flow rate throughout the scramjet as a function of the angle of attack is also presented in the CFD model in addition to the pressure, density, temperature and Mach fields. Before presenting the corresponding results, a comparison between the aerodynamic coefficients in terms of the angle of attack of both models is carried out in order to properly validate the CFD model. The paper clarifies the requirements needed to make sure that both oblique shock waves originating from the leading edge meet just at the scramjet inlet clarifying the advantages of fulfilling such condition.