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A novel actuator disk model (ADM) coupled with lifting-line theory is proposed in this paper. Several virtual planform blades are placed on a disk plane with a constant azimuthal interval, and the lifting-line theory is applied to each blade to predict the effective angle of attack. The proposed model considers the local lift and drag forces acting on disk surface cells by interpolating the predicted effective angle of attack with various azimuth angles to the actuator disk plane; therefore, the proposed model considers individual blade tip vortices without tip loss functions. Experimental data for hover and forward flight rotors are used to validate the proposed model. For hovering flight, sectional thrust based on collective pitch angles predicted by the modified ADM was similar to that obtained in the experiments. For forward flight, the inflow above the rotor estimated by the proposed ADM was similar to that obtained in the experiments and by using other numerical methods. Thus, the developed ADM can be used for rotor performance analysis under the main flight conditions of V/STOL. [ABSTRACT FROM AUTHOR]

A novel actuator disk model (ADM) coupled with lifting-line theory is proposed in this paper. Several virtual planform blades are placed on a disk plane with a constant azimuthal interval, and the lifting-line theory is applied to each blade to predict the effective angle of attack. The proposed model considers the local lift and drag forces acting on disk surface cells by interpolating the predicted effective angle of attack with various azimuth angles to the actuator disk plane; therefore, the proposed model considers individual blade tip vortices without tip loss functions. Experimental data for hover and forward flight rotors are used to validate the proposed model. For hovering flight, sectional thrust based on collective pitch angles predicted by the modified ADM was similar to that obtained in the experiments. For forward flight, the inflow above the rotor estimated by the proposed ADM was similar to that obtained in the experiments and by using other numerical methods. Thus, the developed ADM can be used for rotor performance analysis under the main flight conditions of V/STOL.

The image vortex model is widely used in lifting line method to predict the flow induced by the shroud and hub surface in ducted fan, but it does not perform well in lift fan design due to the zero far field inflow. In this paper the theoretical defects and numerical error propagation characteristic of the image vortex model in simulating duct surface are studied. Then the vortex rings correction based on image vortex model is verified and applied in lifting line method. In order to test the improved method, a 150 mm diameter lift fan is designed by the modified lifting line method, after that, analyzed by the modified lifting line itself and RANS solver respectively. The results show that the contribution of the vortex rings at the rotor accounts for 50% of the total induced velocity, and it accounts for 35% at the stator, which verifies the necessity of the vortex rings correction. The performance of the rotor and stator geometry is consistent with the design expectation, the efficiency is up to 90.97% by numerical simulation and 88.32% by experimental measurement, which confirms the reliability of the modified lifting line method developed in this paper especially on lift fan design. [ABSTRACT FROM AUTHOR]

The core of the short takeoff and landing problem in thrust-vectoring V/STOL vehicles is the tilt angle control of the thrust vector nozzles. This work resolves it by figuring out the optimal tilt angle time history with optimization methods. Since the optimization process is constrained by the transition corridor of the vehicle and the mission requirements, the transition corridor is firstly established by the AES theory with the longitudinal model of the V/STOL protype, where the jet-induced effect of the 3BSD nozzle and the lift fan are especially considered. In addition, the control redundancy caused by the multiple physical control actuators is addressed by a suitable control allocation and flight-mode-based control strategy, which ensures a smooth conversion. By establishing appropriate mission references and optimization constraints, the optimal control strategy and the corresponding transition process are obtained, based on the direct inverse and SQP algorithms.

Personal aerial vehicles, an innovative transport mode to bridge the niche between scheduled airliners and ground transport, are seen by aviation researchers and engineers as a solution to provide fast urban on-demand mobility. This paper reviews recent research efforts on the personal aerial vehicle (PAV), with a focus on the US and Europe led research activities. As an extension of the programmatic level overview, several enabling technologies, such as vertical/short take-off and landing (V/STOL), automation, distributed electric propulsion, which might promote the deployment of PAVs, are introduced and discussed. Despite the dramatic innovation in PAV concept development and related technologies, some challenging issues remain, especially safety, infrastructure and public acceptance. As such, further efforts by many stakeholders are required to enable the real implementation and application of PAVs. [ABSTRACT FROM AUTHOR]