Min Chang

The hybrid vortex particle method (HVPM) combines the low-dissipation property of the meshless vortex particle method with the efficient treatment of body-surface boundaries of the panel method, making it suitable for fast unsteady-flow simulations of wings and rotors. The HVPM typically uses a conventional one-to-one panel-to-vortex particle conversion mode, which strongly couples particle spatial resolution to the panel size and the computational time step, thereby affecting computational efficiency and accuracy. Accordingly, this paper proposes an adaptive HVPM based on a spatial–temporal resolution decoupling strategy. The method introduces a dimensionless vortex-particle overlap rate parameter (ROL) to partition the wake vortex panels dynamically and combines it with a bilinear interpolation model to determine the doublet strengths on sub-panels. That is, the adaptive HVPM can achieve adaptive panel-to-vortex particle conversion, i.e., making the spatial distribution of vortex particles independent of the panel size and the time step. The case validation for a NACA0015 rectangular wing reveals how setup parameters (e.g., the number of panels, ROL, and vortex-particle core radius) influence adaptive HVPM simulations. Its predicted load and vortex wakes are in good agreement with the corresponding high-fidelity simulation results or experimental data. In addition, the validation results of the Beaver rotor demonstrate that the adaptive HVPM overcomes the defect of non-uniform vortex particle distributions in HVPM simulations. At an approximate level of computational accuracy, the adaptive HVPM has a much lower computational cost than the high-fidelity simulation method and achieves higher computational efficiency than the HVPM.

To achieve underactuated control, a novel swashplateless rotor configuration of asymmetric inclined hinges which can be driven by periodic sinusoidal torque is studied, hopefully eliminating the conventional swashplate mechanism and multiple actuators. Therefore, the traditional mechanism can be intelligently replaced by software. However, high-frequency torque variation will invariably result in vibration noise and energy loss.Thus it is critical to properly design the swashplateless rotor in order to achieve a control process with less torque variation. As a result, in both numerical simulation and experiments, we performed sensitivity analyses on related design parameters such as hinge eccentricity, hinge inclined angle, and wingtip hammer position. The parameter effect on swashplateless rotor control was discovered through the analyses, and the basic law of its design was obtained.