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This article conducts unsteady numerical calculations on lateral thrusters under arrival conditions, revealing the induced unsteady force characteristics under the interference between lateral thrusters and pod packages. The calculation results show that the lateral force and torque of the lateral propeller point towards the bow of the ship, and the main characteristic frequencies of pressure pulsation are blade frequency and its harmonics; The thrust and torque pulsation of the side thrusters on the bow side of the ship have maximum values; The bottom of the lateral thrust channel exhibits stronger pressure pulsation compared to other positions. The calculation results of this article determine the position and characterization form of the excitation force of the lateral thruster, providing a basis for the design of low-noise lateral thrusters.

Conventional variable geometry supersonic inlets have defects of high redundant mass, large size and poor control effect. A variable geometry inlet with the SMAs as the control element is experimentally studied in a high-speed wind tunnel. The control scheme for inlet shapes is proposed, and the operating characteristics of the variable geometry inlet under typical conditions have been examined. The deformation of the throat and forebody can ensure stable operation of the inlet in a wide flight Mach number domain.

This paper presents a novel cross-medium fixed-wing vehicle with a deformable nose cone (CFV-DNC) and thoroughly investigates the impact of nose shape on the water-entry performance of the full vehicle configuration through both simulations and experiments. The CFV-DNC utilizes a split-flaperon tailless aerodynamic configuration as its main fuselage body. A motion mechanism combining mechanical support plates and worm gear mechanisms is employed to achieve continuous curvature variation of the nose cone. Through CFD numerical simulations and experimental validation, the influence patterns of nose shape on the water-entry trajectory and resistance experienced by the full vehicle were revealed. Under a water-entry angle of 30°, the forward displacement initially increases and then decreases with the rising fineness ratio, reaching its maximum at a fineness ratio of 4.6. The peak drag forces of the nose and wing exhibit dual peaks with opposing trends, wherein the peak nose drag is highest at a fineness ratio of 0.2 and lowest at 3.8. The conclusions in this paper will be useful for subsequent studies on cross-media vehicles.

What is the difference between the wake past a rocket with sharp nose or with oblate nose? The measurement by Particle Image Velocimetry tries to answer at velocities 5 – 20 m/s (i.e. Reynolds numbers 20 thousand to 79 thousand). A simple model rocket is 3D printed with body diameter of 60 mm, total height 4 D, i.e. 240 mm. The maps of mean stream-wise velocity, stream-wise fluctuations and span-wise fluctuations are compared.

The shape of the ship’s forebody has a greater impact on the ship’s resistance, and a reasonable optimization of the forebody can play a role in reducing the propulsion power and optimizing the resistance performance. Under the premise of Rankine source method of potential flow wave theory as the theoretical basis, SHIPFLOW software is used as the calculation tool, and CAESES software is used as the optimization tool to study the optimal design of the ship with minimum wave resistance. In the optimization process, a real ship is taken as the object, and the optimal solution of the rising wave resistance coefficient is calculated with the rising wave resistance coefficient as the objective function and the ship speed and displacement as the constraints. The real ship is selected as the mother ship, the parameters of the hull shape are taken as the design variables, and the shape of the forebody is optimized by the Lackenby shift method, so as to obtain a ship shape with less wave resistance at the same speed and within the displacement limit. The results show that the improved ship shape has obvious effect of reducing the wave resistance, which verifies the effectiveness and feasibility of this method for ship shape optimization

The hypersonic aircraft can achieve the effect of reducing drag by adopting a forebody ring-shaped lateral jet flow method, which. However, due to the jet interference effect, it will change the flow field structure and load distribution of the entire aircraft. Using a three-dimensional numerical simulation method based on the Navier-Stokes (NS) equations, a study on the jet interference effect from low to high jet stations and angles of attack (from 0° to 10°) was conducted for the cone-cylindrical skirt shape. The returns indicate that the higher the jet pressure ratio, the better the drag reduction effect, which is mainly concentrated in the conical and skirt sections of the aircraft; merely increasing the spike will lead to a decrease in the aircraft’s moment coefficient. As jet pressure increases, the downward force moment coefficient of the aircraft increases gradually.

The nose landing gear of unmanned aerial vehicles (UAVs) is essential for ensuring safety and stability during takeoff and landing. Excessive vibrations from structural dynamics and runway interaction can cause serious component damage. This study investigates the application of Butterfly-Like Metallic Dampers (BLMDs) as passive devices to reduce vibrations through energy absorption and dissipation. Using Finite Element Method (FEM) simulations, both static and dynamic analyses were performed on UAV nose landing gear equipped with BLMDs to examine how dimensional variations affect stiffness, energy dissipation, and dynamic response. The results identified Model S6 as the most effective configuration, offering a stiffness of 15,854.27 N/mm and energy dissipation of 15,735.68 N.mm. Dynamic tests revealed a trade-off between stiffness and vibration response: Model S6 reduced displacement by 33% compared to the baseline model (S1) but increased acceleration by 24.53%, whereas Model S7, with lower stiffness, decreased acceleration by 24.53% but increased displacement. This inverse relationship shows that higher stiffness limits displacement but amplifies acceleration, while lower stiffness has the opposite effect. The study underscores the need to balance stiffness and dynamic performance in BLMD design to achieve optimal vibration mitigation and enhance the durability of UAV landing gear.

The finite element models of B4C ceramic/metal composite plates penetrated normally by the conical-nose steel projectiles are established with LS-DYNA code. From the numerical simulations, strain contours and penetration process are obtained, and the failure mechanism of composite plates is analyzed. The residual velocity versus initial velocity curves of the conical-nose projectiles are plotted. Numerical results of the ballistic limit velocities are found to be in good agreement with available experimental data. Based on the numerical results, the best thickness ratio between ceramic front plate and metal back plate can be obtained for the equal areal density case. The conclusions are helpful for the optimization design of ceramic/metal composite structures.

Under long cruise conditions, the forebody and inlet of a hypersonic vehicle were sensitive to deform under the aerodynamic thermal load, which hurt aerodynamic characteristics, intake performance, and aircraft safety. A pre-deformation method was proposed by using the numerical method of fluid-thermal-structural coupling based on the in-house software, aiming at the static deformation of a typical forebody-inlet model. Three pre-deformed models were combined by the forebody/inlet deformation and then compared the intake performance between the pre-deformed models and the ideal rigid model. The results show that the pre-deformation of the forebody can not only ensure the intake performance partly but also avoid the risk of excessive pressure on the intake wall. The pre-deformation of the inlet can reduce the flow separation near the ramp wall and reduce the pressure of intake, but it also reduces the total pressure recovery coefficient and affects intake performance negatively.

During high-speed atmospheric entry for spacecraft, the severe aerodynamic heating in the shock layer of the forebody flowfield gives rise to high-temperature nonequilibrium effect and radiative effect, which are closely coupled and significantly influence the thermal environment. A coupled flowfield-radiation numerical method is established based on the flow solver AEROPH_Flow, employing the step model for spectral calculations and the discrete ordinates method for radiation transfer. The method is validated by FIRE II flight data, and the radiative and convective heating characteristics of a typical spherical nose under varying Mach numbers are investigated. Key conclusions are as follows: The radiative contribution to total heat flux increases progressively with Mach number, eventually becoming dominant at high speeds. Radiative heating accounts for 70% of the total heat flux at Mach 45, emphasizing the necessity of accurately evaluating radiative effects in thermal protection design. The flowfield-radiation coupling effect causes significant reductions in both convective and radiative heat flux. At Mach 45 for the spherical nose, coupling effect leads to 12% decrease in convective heat flux and a 56% reduction in radiative heat flux compared to decoupled simulations. This demonstrates that decoupled calculations grossly overestimate total heat flux. Thus, coupled flowfield-radiation simulations are indispensable for high-Mach-number applications to ensure accurate thermal load predictions for spacecraft.