Three-Dimensional Flow Analysis over Canard Configuration in Turbulence Model

The canard has been seen as an ominous aerodynamic object for ages this paper is to shed some more light on the effects of canard configuration on the aircraft’s wings. This flow-field analysis is thus being done using a turbulence model solution to take into the effects of a real-time environment where the vortices from the canard are captured more accurately. The analysis has been done meticulously and made to be as error-free as possible under the guidance of Dr. Yagya Dutta Dwivedi.

Aerodynamic Performance of a Coaxial Hex-Rotor MAV in Hover

Micro aerial vehicles (MAVs) usually suffer from several challenges, not least of which are unsatisfactory hover efficiency and limited fly time. This paper discusses the aerodynamic characteristics of a novel Hex-rotor MAV with a coaxial rotor capable of providing higher thrust in a compact structure. To extend the endurance during hover, flow field analysis and aerodynamic performance optimization are conducted by both experiments and numerical simulations with different rotor spacing ratios (i = 0.56, 0.59, 0.63, 0.67, 0.71, 0.77, 0.83, 0.91). The measured parameters are thrust, power, and hover efficiency during the experiments. Retip ranged from 0.7 × 105 to 1.3 × 105 is also studied by Spalart–Allmaras simulations. The test results show that the MAV has the optimum aerodynamic performance at i = 0.56 with Retip = 0.85 × 105. Compared to the MAV with i = 0.98 for Retip = 0.85 × 105, thrust is increased by 5.18% with a reduced power of 3.8%, and hover efficiency is also improved by 12.14%. The simulated results indicate a weakness in inter-rotor interference with the increased rotor spacing. Additionally, the enlarged pressure difference, reduced turbulence, and weakened vortices are responsible for the aerodynamic improvement. This provides an alternative method for increasing the MAV fly time and offers inspiration for future structural design.

Effect of intra-tow flow on plain woven fabric permeability using virtual fiber-voxel element method

A geometric modeling platform based on the virtual fiber-voxel element is proposed to characterize textile reinforcement in a cost-effective way, which could reflect the systemic local changes of the tow path and tow cross-section. The finite volume method is used to solve the governing equation of the boundary value problem, and the permeability of the fabric is calculated by using the flow field data obtained from the model. The flow field analysis and pressure drop in flow direction of different thickness unit cells suggest that the size of inter-tow channels play a vital role in determining the overall in-plane permeability values. The flow channels of the inter tow in warp direction were found to be greater than in the weft direction, which causes the overall permeability to be anisotropic.

Numerical Investigation on a Axial Slot Casing Treatment of a Large Circumferential Interval and Small Opening Area

Axial slot casing treatment is a common method to extend the stall margin of a compressor. Based on the mechanism of unsteady flow control, this paper redesigns axial slots with large circumferential interval and small opening area. To test the effect of this axial slot structure, unsteady numerical simulations were carried out with different slot areas and circumferential intervals. The results show that this novel axial slot casing treatment can significantly improve compressor stall margin. Meanwhile, compared with the traditional axial slot, the efficiency loss is greatly reduced. The flow field analysis shows that the new axial slot structure proposed in this paper can suppress the development of tip leakage vortex and unsteadiness in the tip region at the near stall condition through decreasing the tip loading periodically. Moreover, we find that the slot area is proportional to the improvement of stability margin. Under the same slot area, an excessive number of slots is not conducive to the improvement of the stability margin.