Validation

This chapter provides some comparisons of pyBEMT with experimental results on turbines and propellers. The source code to run these simulations are found in the examples directory of the repository.

Tidal stream turbine

In this example the power and thrust of a tidal stream turbine is compared against results from the experiments presented in [BAHAJ2007]. The airfoil data are obtained from XFOIL using the Viterna extrapolation method to obtain 360 polars.

The figure below shows the simulated power and thrust coefficients compared to the experimental results, and good agreement can be observed.

Propeller

In this example the thrust, torque and efficiency of an airplane propeller is compared against results from the experiments presented in [THEODORSEN1937]. The test case used for comparison is propeller C at a pitch angle of 15 degrees. The propeller uses the CLARK Y airfoil, and the airfoil data are obtained from XFOIL. Note that as pointed out in [MORGADO2015], there is a difference in the definition of pitch angle used in the report compared to common practice today. Hence, the pitch in the simulations is adjusted by 2 degrees compared to the pitch in the report.

The figure below shows the simulated power and thrust coefficients along with the propeller efficiency compared to the experimental results, and good agreement can be observed.

BAHAJ2007

Bahaj A.S., et al. “Power and thrust measurements of marine current turbines under various hydrodynamic flow conditions in a cavitation tunnel and a towing tank.” Renewable Energy 32.3 (2007): 407-426.

THEODORSEN1937

Theodorsen T., Stickle G.W. and Brevoort, M.J. “Characteristics of six propellers including the high-speed range.” Report no. 594-National Advisory Committee for Aeronautics (1937).

MORGADO2015

Morgado J., Silvestre M.A.R. and Páscoa J.C. “Validation of new formulations for propeller analysis.” Journal of Propulsion and Power 31.1 (2015): 467-477.