A multi-thrust and multi-torque aerodynamic balance has been designed for measuring thrusts and torques of a pair of coaxial contra-rotating propellers. The setup allows the independent measurement of performance of each propeller. The results of measurement of first pair of propellers in static thrust mode are presented and indicate the methodology that will be used for future measurements. Various aspects, such as propeller distance and speed of rotation ratio are investigated.

Abstract.A set of small model and UAV propellers is measured both in terms of aerodynamic performance and acoustic noise under static conditions. Apart from obvious correlation of noise to tip speed and propeller diameter the influence of blade pitch, blade pitch distribution, efficiency and shape of the blade is sought. Using the measured performance data a computational model for calculation of aerodynamic noise of propellers will be validated. The range of selected propellers include both propellers designed for nearly static conditions and propellers that are running at highly offdesign conditions, which allows to investigate i.e. the effect of blade stall on both noise level and performance results.

Abstract. The aerodynamics of contra-rotating propellers is a complex three-dimensional problem of an unsteady flow, which is often approached by assuming numerous simplifications. Presented computational model combines a 3D panel method with a force-free vortex wake and a two-dimensional two-equation boundary layer model, in an attempt to capture all the main contributing elements of the flow physics. An emphasis is placed on the interaction of the viscous boundary layer region with the inviscid region and the development of a portable method of their coupling. The kinematics of a force-free vortex wake is supplemented with a vortex aging due to a diffusion. Extra attention is paid to the process of the blade passing through the wake of another blade. To demonstrate the ability of the numerical model, several test cases are presented illustrating the reaction of the system to various operational conditions.