2. Renewable Energy Technologies

Wind Energy — Quiz

Test your understanding of wind energy with 5 practice questions.

Practice Questions

Question 1

Considering the ideal actuator disk model, at what axial induction factor $a$ is the power coefficient $C_p=4a(1-a)^2$ maximized?

Question 2

A wind turbine has $C_p=0.42$, air density $\rho=1.225\,\mathrm{kg/m^3}$, swept area $A=2000\,\mathrm{m^2}$, wind speed $V=10\,\mathrm{m/s}$. What is its mechanical power output $P=\tfrac12\rho A V^3 C_p$?

Question 3

Using the logarithmic wind profile $V(z)=V_{\mathrm{ref}}\frac{\ln(z/z_0)}{\ln(z_{\mathrm{ref}}/z_0)}$ with $V_{\mathrm{ref}}=6\,\mathrm{m/s}$ at $z_{\mathrm{ref}}=10\,\mathrm{m}$ and roughness length $z_0=0.1\,\mathrm{m}$, estimate the wind speed at hub height $z=80\,\mathrm{m}$.

Question 4

In wind turbine grid integration, what does 'synthetic inertia' refer to?

Question 5

In Jensen’s wake model, the wake width $D_w$ at downstream distance $x$ is given by $D_w=D+2k x$. For $D=100\,\mathrm{m}$, wake expansion coefficient $k=0.04$, and $x=3D$, what is $D_w$?