The efficient utilization of propeller slipstream energy is important for improving the ultra-short takeoff and landing capability of Distributed Electric Propulsion(DEP)aircraft.This paper presents a quasi-three-dime...The efficient utilization of propeller slipstream energy is important for improving the ultra-short takeoff and landing capability of Distributed Electric Propulsion(DEP)aircraft.This paper presents a quasi-three-dimensional(2.5D)high-lift wing design approach considering the three-dimensional(3D)effects of slipstream for DEP aircraft,aiming at maximizing the comprehensive lift enhancement benefit of the airframe-propulsion coupling unit.A high-precision and efficient momentum source method is adopted to simulate the slipstream effects,and the distributed propellers are replaced by a rectangular actuator disk to reduce the difficulty of grid generation and improve the grid quality.A detailed comparison of the 2.5D and 3D configurations based on the X-57 ModⅣis performed in terms of flow characteristics and computational cost to demonstrate the rationality of the above design approach.The optimization results of the high-lift wing of the X-57 ModⅣshow that the aerodynamic performance of the landing configuration is significantly improved,for instance,the lift coefficient increases by 0.094 at the angle of attack of 7°,and 0.097 at the angle of attack of 14°.This novel approach achieves efficient and effective design of high-lift wings under the influence of distributed slipstream,which has the potential to improve the design level of DEP aircraft.展开更多
We propose a resolution enhancement method for a lensless in-line holographic microscope(LIHM) by combining the hologram segmentation and pixel super-resolution(PSR) techniques. Our method is suitable for imaging spec...We propose a resolution enhancement method for a lensless in-line holographic microscope(LIHM) by combining the hologram segmentation and pixel super-resolution(PSR) techniques. Our method is suitable for imaging specific target objects in samples, where the in-line hologram is disturbed by other objects in the samples. The resolution-enhancement capability of our method was proved by numerical simulations and imaging experiments while using a standard resolution target in a two-layer setup. We also applied our LIHM system to image the sample of living algae Euglena gracilis in water solution for further demonstration.展开更多
文摘The efficient utilization of propeller slipstream energy is important for improving the ultra-short takeoff and landing capability of Distributed Electric Propulsion(DEP)aircraft.This paper presents a quasi-three-dimensional(2.5D)high-lift wing design approach considering the three-dimensional(3D)effects of slipstream for DEP aircraft,aiming at maximizing the comprehensive lift enhancement benefit of the airframe-propulsion coupling unit.A high-precision and efficient momentum source method is adopted to simulate the slipstream effects,and the distributed propellers are replaced by a rectangular actuator disk to reduce the difficulty of grid generation and improve the grid quality.A detailed comparison of the 2.5D and 3D configurations based on the X-57 ModⅣis performed in terms of flow characteristics and computational cost to demonstrate the rationality of the above design approach.The optimization results of the high-lift wing of the X-57 ModⅣshow that the aerodynamic performance of the landing configuration is significantly improved,for instance,the lift coefficient increases by 0.094 at the angle of attack of 7°,and 0.097 at the angle of attack of 14°.This novel approach achieves efficient and effective design of high-lift wings under the influence of distributed slipstream,which has the potential to improve the design level of DEP aircraft.
基金supported by the Shanghai Pujiang Program(No.12PJ1405100)the National Natural Science Foundation of China(No.61205192)
文摘We propose a resolution enhancement method for a lensless in-line holographic microscope(LIHM) by combining the hologram segmentation and pixel super-resolution(PSR) techniques. Our method is suitable for imaging specific target objects in samples, where the in-line hologram is disturbed by other objects in the samples. The resolution-enhancement capability of our method was proved by numerical simulations and imaging experiments while using a standard resolution target in a two-layer setup. We also applied our LIHM system to image the sample of living algae Euglena gracilis in water solution for further demonstration.
