Experimental investigation of turbulent flow in the near wake of a propeller

An experimental investigation of the near wake of a five bladed 15.50 inch (393.75 mm) diameter DTNSRDC 4767A marine propeller was conducted in the VPI Stability tunnel at an advance ratio of 0.95 in a uniform free stream at 20 ft/s (6.1 m/s). Several types of data were obtained. First, the performance characteristics, thrust, torque, and efficiency, were documented using a six component strain gage balance located in the motor housing. Secondly, the mean static pressures, mean flow velocity components, and flow angularity were measured by a five port yawhead probe. The third type of measurement was made with a straight hot-wire anemometer to find mean and turbulence intensity magnitudes averaged behind the propeller disk. These measurements were made at 21 radial locations and 5 downstream locations: X/D=0.025, X/D=0.200, X/D=0.300, X/D=0.400, X/D=0.500. Finally, the wake from an individual blade was studied by sampling the hot-wire signal at 240 fixed intervals following a constant phase, once per revolution trigger. The samples were stored on a microcomputer operated as a digital storage oscilloscope. These signals were phase averaged to yield the turbulent and mean velocities across the blade wake at ten radial locations. The slipstream (wake) of the propeller was found to contract in the downstream direction due to pressure relaxation. High swirl velocities were found near the hub, while the region of maximum thrust was typically around 0.6R. The individual blade wake data revealed very strong turbulence intensities (up to 32 percent of free stream) in the wake of each blade with relatively low turbulence between the blades.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Aerospace Engineering

Department dc:contributor.department

Aerospace Engineering

Grantor dc:publisher

Virginia Polytechnic Institute and State University

Year dc:date.issued

1987

Author dc:creator

• Holland, Scott D.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/10919/53130

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/53130