Carlos M. Xisto

Analytical modeling of a cyclorotor in hovering state

In the paper it is proposed and described in detail a mathematical model that is able to assist in the design of cycloidal rotors. The method is formulated on a semi-empirical way including unsteady aerodynamic effects that are based on first principles. It is able to predict the overall generated thrust and the power required by the operation of the cycloidal rotor. The model also includes a kinematic package that can provide an instantaneous design and animation of the cycloidal rotor under different regimes of operation. For validation it was addressed three different rotor configurations where it was varied several rotor parameters, namely: pitch amplitude; pitching axis location; blade chord; airfoil thickness; phase angle of eccentricity. It was shown that the proposed model is able to provide a good estimation of thrust and power when compared with the experimental data from these different sources, showing that the semi-empirical approach could be applied in a more general way.

Aerodynamic optimization of cyclorotors

Purpose n n n n nCycloidal rotors, also known as cyclogyros, are horizontal axis rotary-wing machines with potential for Vertical Take-Off and Landing aircraft applications. The paper aims to devise and validate a new semi-empirical analytical model that is capable of assisting in the structural and aerodynamic design of cyclogyros. n n n n nDesign/methodology/approach n n n n nThe analytical model comprises a purely analytical kinematic sub-component that is used for analyzing the structural feasibility of the rotor. Several geometrical parameters are assessed, e.g. the oscillation schedule of the blades as a function of the properties of the pitching mechanical system. The dynamic sub-component of the model is used for estimating the rotor thrust production and power consumption. This sub-component is semi-empirical and uses a calibration function that was devised using the available experimental data. n n n n nFindings n n n n nFor a set of initial conditions and geometrical parameters, the model is capable of providing a real animation of the cyclogyro operation. It is shown that the motion of the blades does not comply with the requirements of a perfect cycloidal curve. The study concerning the simulation of the virtual camber effect on the drum blades, with and without the pitch effect, shows that the virtual camber strongly depends on the chord-to-radius ratio and on the aircraft advance velocity. n n n n nOriginality/value n n n n nA new analytical model capable of assisting in the geometrical and aerodynamic design of cyclogyros is here proposed. The model is capable of providing approximate estimations of the cyclogyro thrust production and power consumption under operating design conditions.

DRAFT:NUMERICAL MODELLING OF ELECTRODE GEOMETRY EFFECTS IN A 2D SELF-FIELD MPD THRUSTER

A self-field MPD thruster in its most basic form consists in a central cathode surrounded by a concentric anode. With thi s coaxial geometric shape is very difficult to use experimenta l techniques to visualize the plasma parameters. In the followingpaper we intend to present some preliminary results for a 2D sel ffield MPD thruster obtained with a new algorithm developed fo r solving the resistive magnetohydrodynamics (MHD) equatio ns. The numerical method is based on the well known PISO algorithm and make use of AUSM-MHD scheme for flux calculation.

Analytic Model Able to Assist in Parametric Design of Cycloidal Rotor Thrusters

In this work we present in a unified way an analytic parametric design method for cycloidal rotors. The method allows for a fast identification of thrust, lift and power parameters as a function of the rotor geometries. Even if, in recent years, the CFD based approaches have been able to provide adequate means to analyse this class of flow, the present model is useful to provide immediate guidelines in the preliminary stages of design, and also to be used as a tool to perform optimization of the cyclorotor. The cycloidal propeller, which can be described as a horizontal rotary wing, offers powerful thrust levels, and a unique ability to change the direction of that thrust almost instantly. The cycloidal propeller is the most efficient form of propeller conceived to date, and was recognized as the solution to overcome propulsion deficiencies associated with airships and other special air vehicles. Several test cases are presented, for three different working regimes, showing the versatility of the developed analysis tool.© 2013 ASME