The invention relates to a method for simulating the unsteady aerodynamic loads being exerted on the external structure of an aircraft, notably in the context of a simulation of the buffeting of a wing surface in an airflow. The method includes a step of measurement of pressure (410) at different points of a grid, a step of calculation of the spectral density at these points (420) followed by extrapolation/interpolation operations to calculate the missing measurements (430), a step of estimation of the pressure coherence (440) for each pair of points of the grid, a step of estimation of the interspectral pressure density (450) for these same pairs of points, from the coherence thus estimated, and a step of calculation of the aerodynamic loads (460) by summing the real part of the interspectral density for the area of the wing surface having a separation of the boundary layer.

A method and apparatus for measuring the propulsive power required to overcome drag forces on a vehicle mounted within a wind tunnel. The apparatus includes a running belt platform driven by a dynamometer and supporting the vehicle placed inside a wind tunnel and controlled by a closed-loop servo control system, which maintains the vehicle centered on the running belt under varying operating speeds and headwind conditions. The power dissipated in drag is measured as the power transferred through ground contact with the wheels of the vehicle.

Systems and methods for monitoring aerostructures are provided. In various embodiments, a method for monitoring an aerostructure may include: receiving a signal from a pressure sensor, the pressure sensor located downstream from the aerostructure; performing a time frequency analysis on the signal to calculate a power level over a range of frequencies; monitoring the power level over the range of frequencies; and determining a susceptibility to a flutter condition based on the monitoring the power level.

Systems and methods for monitoring aerostructures are provided. In various embodiments, a method for monitoring an aerostructure may include: receiving a signal from a pressure sensor, the pressure sensor located downstream from the aerostructure; performing a time frequency analysis on the signal to calculate a power level over a range of frequencies; monitoring the power level over the range of frequencies; and determining a susceptibility to a flutter condition based on the monitoring the power level.

The present disclosure relates to the technical field of aerodynamic and acoustic measurement, in particular to a comprehensive performance test platform for acoustic liner. Based on this comprehensive performance test platform for acoustic liner, the stress of the measured acoustic liner under high sound intensity can be measured by using strain gauges arranged on the measured acoustic liner, the aerodynamic drag of the measured acoustic liner can be measured by using the drag balance, and the acoustic performance parameters of the measured acoustic liner can be calculated based on the sound pressure data obtained by the microphone array. With this test platform, the stress, the aerodynamic drag and the acoustic performance parameters of the measured acoustic liner can be measured simultaneously, which overcomes the problem of inaccurate experimental data obtained in inconsistent experimental conditions caused by conventional separate acoustic liner tests.

Disclosed herein is a technique of configuring flexible photovoltaic tracker systems with high damping and low angle stow positions. Under dynamic environmental loads implementing a high amount of damping (e.g., greater than 25% of critical damping, greater than 50% of critical damping) or a very high amount of damping (e.g., 100% or greater of critical damping, infinite damping) enables the flexible tracker system to prevent problematic aeroelastic behaviors while positioned in a low stow angle. The disclosed technique is further applied to a prototyping process during wind tunnel testing.

Disclosed herein is a technique of configuring flexible photovoltaic tracker systems with high damping and low angle stow positions. Under dynamic environmental loads implementing a high amount of damping (e.g., greater than 25% of critical damping, greater than 50% of critical damping) or a very high amount of damping (e.g., 100% or greater of critical damping, infinite damping) enables the flexible tracker system to prevent problematic aeroelastic behaviors while positioned in a low stow angle. The disclosed technique is further applied to a prototyping process during wind tunnel testing.

A system for testing aerodynamic characteristics of a high-speed moving vehicle-bridge system and subsidiary facilities thereof under a crosswind includes a vehicle model, a starting mechanism, a buffer mechanism, a wind tunnel test section and guide rails. The guide rails pass through the wind tunnel test section; the starting mechanism and the buffer mechanism are separately located at both ends of the guide rails. The guide rails include an acceleration section and a deceleration section. The starting mechanism is located in the acceleration section, and the buffer mechanism is located in the deceleration section; the vehicle model starts to run at the starting mechanism and stops at the buffer mechanism; an instantaneous speed of the vehicle model in the acceleration section is not less than 100 km/h. The present invention carries out simulation tests on various infrastructures, their subsidiary facilities and trains through scale models.

A system for testing aerodynamic characteristics of a high-speed moving vehicle-bridge system and subsidiary facilities thereof under a crosswind includes a vehicle model, a starting mechanism, a buffer mechanism, a wind tunnel test section and guide rails. The guide rails pass through the wind tunnel test section; the starting mechanism and the buffer mechanism are separately located at both ends of the guide rails. The guide rails include an acceleration section and a deceleration section. The starting mechanism is located in the acceleration section, and the buffer mechanism is located in the deceleration section; the vehicle model starts to run at the starting mechanism and stops at the buffer mechanism; an instantaneous speed of the vehicle model in the acceleration section is not less than 100 km/h. The present invention carries out simulation tests on various infrastructures, their subsidiary facilities and trains through scale models.

A photovoltaic system includes a collection of photovoltaic modules, a base supporting the collection of photovoltaic modules, and a damper coupled between the collection of photovoltaic modules and the base. The damper resists movement of the photovoltaic modules relative to the base. The damper has a first damping ratio when the collection of photovoltaic modules moves at a first rate relative to the base and a second damping ratio when the collection of photovoltaic modules moves at a second rate relative to the base, and the damper passively transitions from the first damping ratio to the second damping ratio.