Open water tests of a propeller carried out in KHRC conventional cavitation tunnel T-32.
The propeller model is mounted in the centre of the measuring section, driven by a shaft from upstream. A non-rotating smooth transition between the upstream shaft and the propeller hub is arranged.
At the open water test, thrust and torque are measured at a range of different advance numbers (J) and cavitation numbers (σ) by changing the shaft speed and tunnel pressure at constant water velocity, unless some limitations in the measuring system require lower velocity.
Any combination of ahead/astern conditions with positive or negative thrust/torque can be obtained, i.e. tests in all four quadrants.
For a controllable pitch propeller the procedure is repeated for different pitch settings. Different water velocities can be used to investigate the influence of Reynolds number.
The result is presented in a diagram showing non-dimensional thrust and torque coefficients, KT and KQ, as well as the open water efficiency, η0 as a function of the advance number, J for different pitch settings and cavitation numbers.