QuasiSteady + Section
Type Definition
Aeroelasticity.QuasiSteadySection — TypeQuasiSteadySectionCoupling model for coupling a quasi-steady aerodynamic model based on thin airfoil theory (see QuasiSteady) and a two-degree of freedom typical section model (see [Section()]). This model introduces the freestream velocity $U$, air density $\rho$, and the Prandtl-Glauert compressibility factor $\beta$ as additional parameters.
The parameters for the resulting coupled model (as defined by the parameter function) defaults to the parameters for each model concatenated into a single vector.
Example Usage
- Aeroelastic Analysis of a Typical Section
- Time Domain Simulation of a Typical Section
- Aeroelastic Analysis of the Goland Wing
- Steady State Aeroelastic Analysis of a Highly Flexible Wing
- Aeroelastic Stability Analysis of a Highly Flexible Wing
Theory
This model is defined by coupling quasi-steady thin airfoil theory aerodynamics
with the typical section model.
To facilitate this coupling, the freestream velocity components $u$ and $v$ are assumed to be aligned with the undeflected chordwise and normal directions, respectively, so that
\[u \approx U_\infty \\ v \approx \dot{h} \\ \omega \approx \dot{\theta}\]
where $U_\infty$ is the freestream velocity magnitude, $\theta$ is pitch, and $h$ is plunge. To capture the effect of twist on the circulatory lift (since it is no longer implicitly modeled by the $\frac{v}{u}$ quantity) twist is added to the effective angle of attack from the quasi-steady model so that the effective angle of attack is now given by
\[\alpha_\text{eff} = \theta - \frac{v}{u} + \frac{b}{u}\left( \frac{1}{2} - a \right) \omega - \alpha_0\]
The original expression for the effective angle of attack may be used by defining the new variable $\bar{v} = u \theta + v$ such that
\[\alpha_\text{eff} = -\frac{\bar{v}}{u} + \frac{b}{u}\left( \frac{1}{2} - a \right) \omega - \alpha_0\]
A small angle assumption is also used to define the lift about the reference location as
\[\mathcal{L} \approx \mathcal{N}\]
where $\mathcal{N}$ is the normal force per unit span at the reference location.