Project description

State of the art Background

The investigation on active control technologies in rotorcraft environment is currently one of the major research topics in the fields of aerodynamics and aerospace structures due to the strong demand to reduce the power consumption whilst preserving flight performance.

In a recently envisaged morphing technique, named Variable Droop Leading Edge (VDLE), a dynamically deforming leading edge control is employed to improve rotor blade performance by optimizing the blade airfoil shape. In this technique, however, a significant portion of the section lift is lost due to the leading edge deformation.

This drawback can be overcome by actively controlling Gurney flap (AGF) deployment in the appropriate portion of the rotor disk. It is only very recently that the aerodynamic performance of such devices have been investigated numerically in two- and three-dimensional configurations and experimentally in two dimensions. AGFs have never been tested on a rotor. This is the baseline where the project starts.

Objectives

The main objective of the present project is to measure the performance of a helicopter main-rotor model with an AGF integrated in each blade. The goal will be achieved by means of a comprehensive wind tunnel test campaign carried out in the Wind Tunnel of Politecnico di Milano.

In order to improve the insight into the effects of the AGFs the test campaign will involve the use of Particle Image Velocimetry (PIV) to measure the velocity field and to evaluate the pressure distribution around the blade. The derivation of a pressure field from PIV data is a very attractive technique that has been recently proposed for time-varying flow applications. This method represents a non-invasive pressure field measurement to be used in applications where traditional methods such as probes and pressure ports present some difficulties, for instance in terms of integration in the rotor blade model. Therefore, a complementary objective will be the development and the accuracy evaluation of a technique aimed to obtain the pressure distribution on the rotor blade section starting from PIV velocity data.

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