Narrow Results

When aircraft pass through the clouds that contain super cooled water droplets during aviation, the droplets collide with the wing surface and ice is formed, which induces a significant threat to aviation safety. Studies on droplet movement in gaseous medium are prerequisite for deicing/anti-icing researches. So, in this work, an experimental study is performed on water droplet deformation as the droplets approach the leading edge of an airfoil. This experiment is carried out in a vertical wind tunnel, with a NACA0012 airfoil model assembled 4.3 m downstream of the droplet generator. The influence of Weber number (ranging from 0.2 to 36) on the deformation of a 2 mm diameter droplet is thoroughly investigated. The results indicate that droplets maintain initial form with Weber number under 10; after that droplet deforms into remarkable bag deformation as Weber number reaches to 19, and bag-stamen deformation mode as Weber number is above 20. This observed correlation between Weber number and deformation mode is validated through comparing with published simulation results. Furthermore, using the high-speed camera, clear images of the droplet structure during the deformation process are taken and are shown in detail in this work.

An aerofoil commonly used in aerospace engineering to produce lift is also employed in the motor sport industry to produce downforce for improving traction during cornering. This paper investigates aerofoil surface modification through ‘golf ball dimpling’, used to reduce flow separation behind a golf ball. The studies of other researchers have shown that this type of design can have a positive effect on improving aerofoil performance. However, no optimization information of dimple sizing is given in literature. Therefore, three types of dimpling sized at 5, 10 and 15 mm are applied to the surface of a NACA 6615 wing at 25% chord length from the leading edge in this study using Computational Fluid Dynamics (CFD) as an initial design process. Then a physical model, made through 3D printing additive manufacturing (AM), is tested at angles of attack (AoA) ranging from $0^{\circ }$ to $20^{\circ }$ and wind speed up to 30 m/s in a subsonic wind tunnel. Experimental and CFD results show that the smallest dimple size provides the most significant increase on lift to drag ratio at high AoA above $10^{\circ }$. This ratio increases further with the wind speed, indicating that a high AoA wing favors down force to improve drag reduction performance.

Usually, force tests and pressure tests are conducted with different model in wind tunnel which could cause trouble for aircraft design as the pressure test results always could not match the force test results. So attempts to do force tests along with pressure tests are conducted. Results show that it is possible to do force test based on pressure-test-model when some improvements are done with the model and sting. Both force and pressure test results can be measured at the same time. The amount of pressure test results need not be reduced, and yet precision and accuracy of the force tests are acceptable for aircraft design, and this technology can be popularized with low cost.

Wind effects on solar panels mounted on façade of high-rise residential building are studied through wind tunnel test. The model with scale ratio of 1:80 is adopted. Results show that the top floor panel is dominated by the upward negative wind load, and the panel at the mid height floor suffers the downward positive wind load, when the panels are mounted on the windward face. The influence of different inclination angles on force coefficient of the panel is also studied. It is found that positive peak force coefficient increases with the increase of panel’s inclination angle, most unfavorable extreme wind suction decreases with increase of panel’s inclination angle. Results show that the location of panels has significant effect on the design wind load. The peak force coefficient values of $-3.50$ and $+1.50$ can be used as the recommended values for design wind coefficients of the top floor panels. Peak force coefficient values of $-3.0$ and $+2.5$ can be used as the recommended values for design wind coefficients of the mid floor panels. The correlations between wind loads on different panels are also examined to check the flow mechanism around the panel. Different trends can be clearly checked from the results for different incident wind directions, suggesting the complex flow condition near panels. The greater the panel inclination is, the higher the correlation of net force coefficient between two adjacent panels is.

This paper demonstrates the design of the airfoil of small wind turbines, the bionic airfoil was inspired by the morphology of the swallow's extended wing. The wind tunnel tests on the bionic and standard airfoils NACA4412 were conducted, and the aerodynamic performances of the airfoils were numerically investigated. The results show that the bionic airfoil has better aerodynamic performance, the lift coefficient and lift-drag ratio are larger than those of the NACA4412; with the angle of attack increases, both the bionic and standard airfoils stall, but the stall characteristics of the bionic airfoil are better.

A new inject blowing supersonic wind tunnel was designed for the development of supersonic aircraft in current and future. In wind tunnel experiment, the location velocity and location accuracy of attack angle mechanism directly influence its quality and efficiency. For this, the calculation, analysis, simulation and optimization of control strategy were done based on the introduction of the attack angle mechanism in supersonic wind tunnel. At last, actual experiment was done and the result indicated that the control method was steady, accurate and rapid.