Wind Turbine Aerodynamics - 10 - Predicting Noise
23 August 2026, Pascal Weihing
BPM model for trailing edge noise prediction
Total sound pressure level is modeled by contributions from the suchtion $s$ and pressure $p$ sides and the effect of the angle of attack $\alpha$
$$ L_{p, TBLTE} = 10log_{10}\left(10^{L_{p, \alpha} / 10}+10^{L_{p, s} / 10} + 10^{L_{p, p} / 10} \right) $$
How do the contributions of the suction and pressure sides differ in the spectrum?
- when airfoil creates lift, $\delta^_p$ is typically smaller than $\delta^_s$
- level scales with $10 log_{10} \delta^*$
- for a given logal mach number, $\frac{St_p}{St_{peak}} = 1$ is reached at higher frequencies$
level is lower on the pressure side
peak frequency is higher on the pressure side
The Empirical BPM Model
| pros | cons |
|---|---|
| simple implementation | model does not take into account the airfoil shape (derived for NACA0012) |
| very few input quantities required ($\alpha, \delta^*, Re$) | model contains explicit angle of attack ranges |
| very fast when using XFOIL boundary layer data | model typically overpreducts high frequencies |
| shape of spectra and peak region predicted reasonably well | -- |
NEXT UP: The TNO model for trailing edge noise prediction