Performance Measurements, Flow Visualization, and Numerical Simulation of a Crossflow Fan

Recently, NASA has placed emphasis on the need for a more robust civil transport system intended to alleviate congestion in ground and air traffic near major cities. This has resulted in funding for research into various aspects of this broad goal. One such research program encourages the development of civil alternatives to private ground transport, the intent being to reduce ground traffic by replacing the private automobile with a similarly sized and purposed vertical takeoff and landing (VTOL) vehicle. VTOL designs that do not incorporate exposed or otherwise hazardous lifting and propulsive devices would be safer than those that do. The research conducted in preparation for this thesis was intended to evaluate one such device: the enclosed crossflow fan. A 12-inch diameter, 1.5-inch span crossflow fan test apparatus was constructed and tested using the existing Turbine Test Rig (TTR) as a power source. Instrumentation was installed and a data acquisition program was developed to measure the performance of the crossflow fan. Performance measurements were taken over a speed range of 1,000 to 7,000 RPM. Results comparable to those measured by Vought Systems Division of LTV Aerospace in 1975 were obtained. At 6,000 RPM, a thrust-to-power ratio of one was determined; however, at 3,000 RPM twice the thrust-to-power ratio was measured. Flow visualization was conducted using dye-injection methods. Performance and flow visualization results were compared to predictions obtained from 2-D numerical simulation conducted using Flo++, a commercial PC-based computational fluid dynamics software package by Softflo. A possible design for a lightweight, civil V/STOL aircraft is suggested using a similar crossflow fan apparatus for both lift and propulsion. (5 tables, 49 figures, 13 refs.)Naval Postgraduate School Monterey CA is the author of 'Performance Measurements, Flow Visualization, and Numerical Simulation of a Crossflow Fan', published 2003 under ISBN 9781423502869 and ISBN 1423502868.