Nonlinear Analysis of Cavitating Propellers in Nonuniform Flow
Abstract
The work presented in this thesis represents the latest in an on-going effort within the propeller hydrodynamics community to obtain rational design stage estimation of dynamically varying blade loads and shaft/bearing forces for cavitating propellers. To this end, the unsteady cavitating flow about a marine propeller is treated in nonlinear theory by employing a low order potential based boundary element method. The steady state oscillatory solution is obtained by incremental stepping in the time domain. The three dimensional, nonlinear and time dependent boundary conditions are satisfied on an approximate boundary consisting of the propeller surface beneath the cavity and the portion of the blade wake surface overlapped by the cavity. This solution represents the first iteration of a completely nonlinear solution in which the exact boundary conditions are satisfied on the exact flow boundary, including the cavity free-surface. It is then shown that the convergence of such an iterative solution for two-dimensional flows is remarkably fast and that the accuracy of the first iteration solution is sufficient for a wide range of operating conditions. Emphasis is placed on developing an efficient and robust iterative scheme to predict general cavity planforms. The numerical method is shown to be convergent and consistent with fully nonlinear results. Computed results are compared to those from linear theory, linear theory with leading edge corrections, and to published experimental measurements and observations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 16, 1992
- Accession Number
- ADA258215
Entities
People
- Neal E. Fine
Organizations
- Massachusetts Institute of Technology