Viability of Cross-Flow Fan with Helical Blades for Vertical Take-off and Landing Aircraft

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Authors
Kwek, Howe Leng
Subjects
cross-flow fan (CFF)
vertical take-off and landing (VTOL)
straight blades
computational fluid dynamics (CFD)
ANYSY-CFX
helical blades
Advisors
Hobson, Garth V.
Date of Issue
2012-09
Date
Sep-12
Publisher
Monterey, California. Naval Postgraduate School
Language
Abstract
The cross-flow fan (CFF) is a lifting and propulsion device that retains the advantages of a fixed-wing aircraft by using a ducted lift fan. There is no upper limit to the rotor length-to-diameter ratio of a CFF, allowing the device to be installed along the length of the wing or lifting device. The CFF discharged vector can be easily rotated about the fan axis since the fan has no angular requirements, further allowing the capability of vertical take-off and landing (VTOL) by thrust vectoring. CFF possess the potential to propel an airframe to flight; however adequate thrust must be produced by the CFF in order for it to realize VTOL. Conventional CFFs designs with straight blades produce unacceptable noise levels for personal air vehicle operation. It is believed that helical blades could solve the sound pressure level problem and produce more thrust to aid VTOL. Using computational fluid dynamics (CFD) software, ANSYS-CFX, a three-dimensional (3-D) straight-bladed model was validated against previous studys experimental results. A 3-D model with helical blades was constructed to investigate the performance. The analytical results have shown that helical blades could increase the thrust performance of a CFF, and could possibly realize VTOL.
Type
Thesis
Description
Series/Report No
Department
Engineering Science (Mechanical Engineering)
Organization
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Distribution Statement
Approved for public release; distribution is unlimited.
Rights
This publication is a work of the U.S. Government as defined
in Title 17, United States Code, Section 101. As such, it is in the
public domain, and under the provisions of Title 17, United States
Code, Section 105, is not copyrighted in the U.S.
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