Experimental investigation of non-uniform flow past propellers

• Main Author: Mallory, David A.
• Other Authors: Aerospace and Ocean Engineering
• Format: Others
• Language: en
• Published: Virginia Polytechnic Institute and State University 2020
• Subjects: LD5655.V855 1985.M244; Fluid dynamics; Propellers > Experiments
• Online Access: http://hdl.handle.net/10919/101447

An experimental investigation of non-uniform flow past a 1.615 foot, 3-bladed propeller was conducted in the Virginia Tech 6 foot by 6 foot Stability Wind Tunnel. The free stream velocity was 44.5 ft/sec and the propeller rpm 1400. A screen disk consisting of two circular meshes, one 15 inches in diameter and the other 5, along with a 30 degree wedge having a 7.5 inch radius, was used to create the non-uniform inflow. The screen disk was chosen to simulate a wake flow behind a slender body with an attached appendage. The propeller was operated at self-propelled mode with respect to the drag of the screen disk. Several types of measurements were completed on the propeller and the near wake. First, the propeller performance quantities were measured. The second type of measurements were the mean flow quantities, which included the mean velocities and static pressures. These were obtained by using a five hole yawhead probe. The third type of measurements were made with an x-wire probe, constant temperature anemometer and an r.m. s. meter. These allowed all the turbulence quantities, intensities and shear stresses, to be obtained. All turbulence quantities were averaged in the peripheral direction. The results of the mean and turbulent flow under the non-uniform flow condition are documented and discussed in detail. The 3-D non-uniform inflow caused the location of the maximum thrust to be shifted from . 7R, previously found for uniform inflow for the same propeller, to .88R while the location of maximum swirl was shifted inward from .6R to .5R. The turbulence quantities were sensitive to the non-uniform mean inflow and the upstream turbulence created by the screen disk, especially in the wake of the wedge region. This was generally observed in the form of higher turbulence intensities and shear stresses. This data can be used to verify and refine turbulent transport models and computational methods for flows of this type. === M.S.