Thrust Augmentation Study of Cross-Flow Fan for Vertical Take-Off and Landing Aircraft

Abstract

Vertical Take-Off and Landing (VTOL) has primarily seen research and development in the two traditional fields, namely the rotary wing and jet propulsion, with each seeking incremental improvements in thrust generation and fuel efficiency, respectively. In recent years, there has been increasing interest in the viability of the Cross-Flow Fans (CFF) being the primary source of aircraft propulsion. There has been measured success in horizontal flight; however, VTOL propulsion with CFFs remains elusive. The current study seeks to determine the feasibility of combining two CFFs in a back-to-back configuration that could augment the thrust generated, thus making VTOL a reality. Making use of an optimized CFF housing, the research aimed to maximize the thrust generated in the above mentioned configuration by varying the gap between the CFFs. Computational fluid simulations of the dual CFF configuration was performed using ANSYS CFX to find the thrust generated as well as the optimal operating point. Analysis was done at three different speeds (3,000 rpm, 5,000 rpm and 8,000 rpm) and four different distances between the dual CFFs (26 mm, 52 mm, 78 mm and 104 mm). Thereafter, an experiment was conducted to compare and validate the results of the simulation.