This paper presents wind tunnel experiments to illustrate the effects of surface curvature on the aeroacoustic performance of airfoil E387. For the first time, surface curvature effects are considered in an investigation of the airfoil's self-noise. To distinguish the effects of surface curvature, the CIRCLE method is applied to the airfoil E387 to remove slope-of-curvature discontinuities and the redesigned airfoil is denoted A7. Anechoic wind tunnel tests were performed with E387 and A7 at three low Reynolds numbers to investigate aeroacoustic performance by measuring airfoil self-noise at different angles of attack (AoA) and spatial positions. At 2 • and 4 • AoA, A7 presents a tone with a reduced amplitude compared with E387 due to its improved slope-of-curvature distribution. It is concluded that improving surface curvature distribution improves airfoil aeroacoustic performance.

Sound source localization technology is used to study the noise mechanism generated by flow around a circular cylinder. Detached-eddy simulation is performed to compute the flow field and the far-field noise is calculated with the Ffowcs Williams and Hawkings acoustic analogy. At first the simulation method is validated with the flow around circular cylinder at Re=3900. The numerical results are compared with the experimental data by other researchers. The following case is to simulate the flow around circular cylinder at Re=46000. The acoustic result is found in good agreement with the experimental measurements. The acoustic analogy result is used as an input for the noise localization process. Microphone array technique is applied to investigate sound generated by flow around a circular cylinder with emphasis on sound generation mechanism. Two sound source localization methods are considered, including Delay-and-Sum beamforming algorithm and a high resolution beamforming method. The sound source is associated with the lift dipole at the vortex shedding frequency. The sound source is associated with the drag dipole at the double vortex shedding frequency. The sound source can also be shown at other frequency. With frequency increasing, the strength reduces and there are some other sidelobe sources.

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After generating reference trajectory in the process of reentry guidance for reusable launch vehicle, if the designed bank angle curve is too close to the constraint boundary, there is a great possibility for the obtained reference trajectory to exceed the reentry corridor boundary. This paper proposed a margin searching method, to reduce the likelihood of generating a reference trajectory which exceeds the reentry corridor boundary and to improve the design success rate.

The aim of this work is to propose an accurate and reliable numerical simulation method of gust response, so as to analyze longitudinal stability characteristics of high-aspect-ratio unmanned aerial vehicles (UAVs) under gust response. Based on the dual-time stepping method, the unsteady Navies-Stokes equation was solved. By introducing grid velocity to study the effects of gust, the numerical simulation of gust response was realized. Moreover, the numerical simulation method was verified to be accurate by using the theoretical value and reference value obtained in previous research. The calculation results of the high-aspect-ratio UAV under the 1-cos gust reveal that longitudinal aerodynamic forces of high-aspect-ratio UAVs changed. In the whole range of gust gradient length, the UAVs were always in the state of static stability. However, with the increase of gust velocity, static stability margin decreased. The numerical simulation method of gusts established in this study preferably overcomes the possible numerical oscillations and divergence problems caused by excessive gust velocity. The analysis on longitudinal static stability and stability margin of high-aspect-ratio UAVs under the effects of gusts can ensure flight quality and safety of UAVs under the effects of gusts.