Periodic Reporting for period 1 - FLOVISP (Flow Visualization Based Pressure)
Reporting period: 2015-06-01 to 2016-11-30
The FLOVISP project extended the current capabilities of non-intrusive full-field velocity measurements to the measurement of the flow field pressure. The project has further developed the technique Particle Image Velocimetry (PIV) into a tool for the simultaneous mapping of the three-dimensional velocity vector and the pressure fields including the pressure and aerodynamic forces at the surface of objects immersed in the stream. The work was prioritised to realise a technique that can be moved from research labs and operated by very skilled operators, towards industrial facilities with medium-expertise operators. A unique experiment has been conducted in a large-scale wind tunnel with test section of 3x3 square meters. The experiment replicates the aerodynamic conditions encountered by a cyclist on the racing track and also a scaled ground vehicle (a.k.a. Ahmed body). The novel use of helium-filled soap bubbles (HFSB) as flow tracers has enabled to amplify the measurement volume from a few centimetres up to a meter. For the first time, the aerodynamic force acting on a full-scale cyclist model has been obtained from aerodynamic data. The pressure field reconstructed from the velocity measurement was calculated invoking the momentum equation. The comparison of state-of-the-art force measurements by six-component balance showed excellent agreement within 2% accuracy. It can be concluded that the proposed approach has the potential of bringing a paradigm shift in the way how pressure measurements are conducted: not anymore with invasive and time-consuming probe scanning or with costly models equipped with myriads of pressure sensors, but with versatile, non-intrusive measurements on models whose shape could be modified for real-time optimization of the aerodynamic loads. The economical and societal benefit of this proof-of-concept shall not wait to be demonstrated with many applications already planned in the automotive, aerospace, wind energy and speed sports sectors.