THE EFFECTS OF REDUCED-COST MACHINING TECHNIQUES ON DIMENSIONAL TOLERANCES, POWERING, AND CAVITATION INCEPTION FOR A SUBMERSIBLE PROPULSOR

摘要

The effects of reduced cost machining techniques on dimensional tolerances, powering, and cavitation inception are evaluated as part of a Design-for-Manufacturability and Affordability (DFM/A) study for a submersible vehicle propulsor. Results from several DFM/A propulsors, produced using chord-wise machining paths and a barrel-end mill cutter, are compared with data from a precision baseline propulsor fabricated using a span-wise machining process and a ball-end mill cutter. The DFM/A propulsors differ from each other only in the span-wise step-size employed in the chord-wise machining process. The powering performance of all DFM/A propulsors is shown to fall within 2% of the baseline propulsor. However, cavitation inception performance of the DFM/A propulsors degrades considerably with increased span-wise step-size increment. The degradation in DFM/A propulsor cavitation inception is correlated to coordinate measuring machine (CMM) results, and occurs despite mean blade surface deviations within 0.003 inch (0.0762 mm.) of the design profile.