Study of pressure fluctuations downstream of an aerodynamic singularity

The circuits traversed by a fluid, such as the cooling circuits of nuclear reactors, are the site of vibratory phenomena; these phenomena can be generated, in particular, by fluctuations in the pressure of the fluid at the walls, which excite mechanical resonances of the structures. To be able to determine the pressure fluctuations likely to cause mechanical vibrations, at any point of the structure, it is necessary to know the characteristics of the various singularities commonly encountered in the circuits, namely: characteristics at short distance (direct effects of the singularities) and long-range characteristics (sound sources associated with singularities). It is also necessary to be able to calculate the acoustic amplification at any point of the circuit. A calculation code, the Vibraphone program, allowing the calculation, from the sources of fluctuations, of the response of a circuit satisfies this second requirement. This work consists in determining the short-range characteristics of an abrupt widening