Attitude-pendulum-sloshing coupled dynamics of quadrotors slung liquid containers

Quadrotors suspended water containers may be used for fire-fighting services. Unfortunately, the complicated dynamics in this type of system degrade the flight safety because of coupling effects among the quadrotor attitude, container swing, and liquid sloshing. However, few effects have been directed at the attitude-pendulum-sloshing dynamics in this type of aerial cranes. A novel planar model of a quadrotor carrying a liquid tank under dual-hoist mechanisms is presented. The model includes vehicle-attitude dynamics, load-swing dynamics, and fluid-sloshing dynamics. Resulting from the model, a new method is proposed to control coupled oscillations among the vehicle attitude, load swing, and fluid sloshing. Numerous simulations on the nonlinear model demonstrate that the control method can reduce the undesirable oscillations, stabilize the quadrotor’s attitude, and reject the external disturbances. The theoretical findings may also extend to the three-dimensional dynamics of quadrotors slung liquid tanks, and other types of aerial vehicles transporting liquid containers including helicopters or tiltrotors.

Investigation of Sloshing Effects on Flexible Aircraft Stability and Response

The present paper provides an investigation of the effects of linear slosh dynamics on aeroelastic stability and response of flying wing configuration. The proposal of this work is to use reduced order model based on the theory of the equivalent mechanical models for the description of the sloshing dynamics. This model is then introduced into an integrated modeling that accounts for both rigid and elastic behavior of flexible aircraft. The formulation also provides for fully unsteady aerodynamics modeled in the frequency domain via doublet lattice method and recast in time-domain state-space form by means of a rational function approximation. The case study consists of the so-called body freedom flutter research model equipped with a single tank, partially filled with water, located underneath the center of mass of the aircraft. The results spotlight that neglecting such sloshing effects considering the liquid as a frozen mass may overshadow possible instabilities, especially for mainly rigid-body dynamics.

The influence of obliquely perforated dual-baffles on sway induced tank sloshing dynamics

This paper examines the influence of oblique perforated baffles on the sloshing dynamics of rectangular liquid storage tanks. The analysis presented accounts for sway induced hydrodynamic forces and entropy generation. Internal liquid free surface oscillation is modelled by the volume of fluid method. The effect of baffle geometric parameters, orientation and porosity on loads is examined and numerical results are compared against a set of experiments. Consequently, an engineering method suggesting the optimum size, angle of inclination and topology of baffles for the case of a rectangular tank is presented. It is shown that implementation of optimized oblique porous dual baffles may reduce sloshing loads by up to 15%.