Cavitation erosion: Using the target material as a pressure sensor

Samir Chandra Roy (1) , Jean-Pierre Franc (2) , Marc C. Fivel (1)

1 SIMaP - Science et Ingénierie des Matériaux et Procédés
2 LEGI - Laboratoire des Écoulements Géophysiques et Industriels [Grenoble]

Numerical prediction of mass loss due to cavitation erosion requires the knowledge of the hydrodynamic impact loads generated by cavitation bubble collapses. Experimental measurements of such impact loads using conventional pressure sensors are not reliable (if not impossible) due to the micron size and the very small duration of the loading. In this paper, a new method to estimate these loading conditions is proposed based on cavitation pitting tests and an iterative inverse finite element modeling. The principle of the method is as follows. First, numerous pits corresponding to localized plastically deformed regions are identified from a cavitation test performed in a dedicated tunnel. Then each pit is numerically reproduced by finite element simulations of the material response to a representative Gaussian pressure field supposed to mimic a single bubble collapse. This gives the size and pressure distribution of the bubble impacts. The prime objective of this study is to find out if the target material itself could be used as a pressure sensor or not, i.e., if the cavitation pits left on the surface of the tested specimen could provide the characteristics of the cavitating flow in terms of pressure fields independently of the target material. Pitting tests were done on three materials, namely, 7075 Aluminum alloy (Al-7075), 2205 duplex stainless steel (A-2205), and Nickel-Aluminum Bronze (NAB) at three different flow conditions and the impact loads have been estimated for each identified pit. Very interestingly, a statistical analysis shows that the estimated impact loads are material independent at all flow conditions, provided the material properties are characterized properly. It is also shown that for some materials, the constitutive parameters obtained from compression tests are not satisfactory.

Domaines: Mécanique des fluides [physics.class-ph]

Samir Chandra Roy, Jean-Pierre Franc, Marc C. Fivel. Cavitation erosion: Using the target material as a pressure sensor. Journal of Applied Physics, 2015, 118 (16), ⟨10.1063/1.4934747⟩. ⟨hal-01223687⟩