Giovanni Vorraro

A comparison of nonlinear actuator disk methods for the performance analysis of ducted marine propellers

This paper presents the validation of a generalised semi-analytical actuator disk model as applied to the study of the flow around ducted propellers. The method, which returns the exact solution as a superposition of ring vortex, duly accounts for the rotation of the wake, the convergence of the slipstream, and the nonlinear mutual interaction between the duct and the propeller. Furthermore, it can deal with an arbitrary radial distribution of the load and ducts of general shape. In order to validate the previously mentioned actuator disk model, results obtained through it are compared with those provided by the so-called “CFD actuator disk method”. The latter is a widely diffused tool for the analysis of the flow around open and ducted propellers which models the rotor by means of radial profiles of blade forces distributed over a disk surface. In this paper, evidence has been given of the excellent agreement between the results of the two methods. Thanks to its extremely reduced computational cost the semi-analytical method is well suited to be integrated into design systems based on the repeated analysis scheme of hierarchical type.

Analysis of a New Measurement System of the Chain Strength for Electrically Assisted Bicycles

This paper presents an activity concerning a theoretical/experimental analysis of a new measurement system of the chain strength functional for the control of the electrically assisted bicycles. Such systems are characterized by a driving torque due to the contribution of an electric motor and of the rider. The electrical assistance is commonly regulated taking into account informations such as chain ring rotation, bicycle speed and/or the torque given by the rider. As a consequence, suitable measurements have to be made on board in order to handle the assistance performances and to improve drivability.Copyright

Performance Evaluation and Environmental Analysis of an Electrically Assisted Bicycle Under Real Driving Conditions

This paper describes the on-road test program that was used for a performance study and environmental analysis of an electrically assisted bicycle in the urban area of Naples. For this purpose, the vehicle was tested on different test tracks, cycling over 2000 km, and then making a general assessment about the driving behavior under real conditions.Based on the findings obtained during the different test samples, an appraisal of the electric traction offered by this bicycle on the driving comfort was evaluated for different conditions: electrical assistance at start, on a flat road and when riding uphill. The power requirements in different typical riding situations were also calculated: these results were estimated by experimental kinematic parameters that describe the driving dynamics collected during the real-life applications. An environmental analysis was made and also put against the environmental impact of a thermal moped.Copyright