Use of Athena Vortex Lattice for Preliminary Hydrofoil Design

Abstract

The purpose of this paper is to demonstrate the extent to which the Athena Vortex Lattice program (AVL) is useful in the design of a hydrofoil system for a solar boat. Cedarville University has won the Solar Splash Collegiate World Championship of Solar Boating 8 times in the past 12 years, and was the top university in the Top Class of the 2012 DONG Energy Solar Challenge in the Netherlands. The three main events of the Solar Splash Competition are the high-speed Slalom and Sprint events, and the longer Endurance event. In the past Cedarville has attempted to design and use hydrofoils for the Endurance event without success. Computational Fluid Dynamics (CFD) analysis for a hydrofoil system was conducted by Neola Putnam (2013 team member) using ANSYS’s CFD software, Fluent. Putnam worked with single phase flow modeling 3D hydrofoils. Fluent analysis can be a long and complicated process requiring hours of meshing followed by hours of CPU time for analysis. AVL, as an alternative, is a less complicated program allowing for simple generation of a geometry file. This program also takes a comparatively short time to analyze the imported geometry file. Thus, if AVL reliably predicts lift and drag, it could be used as a preliminary design tool to quickly assess various design options. AVL is a program which models lifting surfaces as vortex lattice sheets to determine the flight characteristics of the surface. The program is written in Fortran and is an inviscid solver. The AVL3.30 User Primer is a reference guide on how to use the program and was used extensively by the authors of this paper when learning to use AVL. Cedarville University also partnered with the company Sea Land Aire Technologies Inc.in Jackson Michigan for aid in using AVL as a design tool. The tool was recommended to Cedarville University by Sea Land Aire as a product which might be of interest to our team in the design of a hydrofoil system. AVL is potentially beneficial to the Cedarville University Solar Boat team in the preliminary design phase of a hydrofoil system. The content of this paper demonstrates the correlation between results from AVL and Fluent analysis for a 2D NACA 4412 foil. Secondly, the paper demonstrates comparable results from AVL for 3Danalysiswith published experimental results. The following sections discuss the use of AVL as a preliminary design tool, and the overall recommendation of the authors as to further use of AVL by Cedarville University in the design of a hydrofoil system.