An experimental investigation of cavitation inception and development on atwo-dimensional Eppler hydrofoil

Cavitation inception and development on a two-dimensional foil with an Eppl er E1817 cross section issued from an inverse calculus have been experiment ally investigated. The foil is theoretically designed to have a wide cavita tion-free bucket allowing a large range of cavitation-free angle of inciden ce (Eppler, R., 1990, Airfoil Design and Data, Springer-Verlag, Berlin). Th e inception cavitation numbers, the noise level, the velocity distribution, the minimum pressure coefficient, the cavitation patterns (bubble, leading edge " band type " cavitation, attached sheet cavity), together with the s heet cavity length have been experimentally determined. Effects on the velo city field have been studied too with a slightly developed cavitation. For angle of incidence larger than 1 deg, a great difference exists between the inception cavitation number and a the theoretical minimum pressure coeffic ient. However it is in agreement with the measured one obtained from veloci ty measurement (for 0 deg<alpha<6 deg). Discrepancy between theory and expe riment on scale models is generally attributed to a flow separation at the leading edge. Although there are some indications of a separated flow at th e leading edge, the velocity measurements do noe show reverse flow with cle arly detected negative velocities expected for a large angle of incidence e qual to 10 deg. Concerning sheet cavity development, the length cavity is f ound to scale as [sigma/2(alpha-alpha(i))(sigma))](-m) with m close to 2, f or length cavities that do not exceed half the foil chord and for alpha/2(a lpha-alpha(i))(sigma)) larger than about 30. [S0098-2202(00)00201-7].