A methodology for predicting solar power incidence on airfoils and their optimization for solar-powered airplanes

摘要

In recent years, there has been great deal of interest in exploration of alternative fuels other than jet fuel for aircraft propulsion in order to reduce the greenhouse gas emissions. For commercial transport as well as military aircraft, there has been a great deal of emphasis on biofuels, which behave like drop-in fuel but generate less CO2 and NOx emissions and, therefore, are more environmentally friendly. However, for small unmanned air vehicle or low-speed personal transportation aircraft, there have been many attempts towards building an all-electric or solar airplane whose wings could possibly be covered with photovoltaic panels to harness sun's energy for propulsion. Most notably, the success of solar impulse has attracted the attention of general public as well as small aircraft enthusiasts. The focus of this paper is on the airfoil/wing design for optimal utilization of solar energy for powering a solar airplane. We analyze the incidence of solar radiation over an airfoil/wing of an airplane. We show that, under some conditions, the incidence is independent of the shape of the airfoil. We develop a more complete model to compute the total solar radiation incident on the airfoil during a cruise flight using the solar tracking equations and geodesy for path creation. The model is based on discretization of both the airfoil and the path. To illustrate the versatility of the model, we employ a genetic algorithm with migration to optimize the airfoil shape during some specific given flight conditions and discuss the results.