4.4.2. List of Symbols
\({}_{l}\) |
low frequency |
|
\({}_{h}\) |
high frequency |
|
\({}_{p}\) |
airfoil pressure side |
|
\({}_{s}\) |
airfoil suction side |
|
\({}_{t}\) |
turbulence |
|
\({}_{0}\) |
reference |
|
\({}_{1}\) |
parallel to airfoil chord |
|
\({}_{2}\) |
normal to airfoil chord |
|
\({}_{3}\) |
blade spanwise direction |
|
\(\alpha\) |
angle of attack |
[rad] |
\(\beta^{2}\) |
Prandtl-Glauert correction factor |
[-] |
\(\delta\) |
airfoil boundary layer thickness |
[-] |
\(\delta^{*}\) |
airfoil boundary layer displacement thickness |
[-] |
\(\theta\) |
airfoil boundary layer momentum thickness |
[-] |
\(\Theta_{e},\ \Phi_{e}\) |
angles between emitter and observer |
[rad] |
\(\rho\) |
air density |
[kg/m3] |
\(\omega\) |
radial frequency |
[rad/s] |
\(A_{w}\) |
A-weight |
[dB] |
\(c\) |
speed of sound |
[m/s] |
\(c_{i}\) |
chord at blade spanwise position i |
[m] |
\(d\) |
blade span at station i |
[m] |
\(\overline{D}\) |
directivity function |
[-] |
\(f\) |
frequency |
[Hz] |
\(G\) |
empirical function |
[-] |
\(h\) |
height of the trailing edge thickness |
[m] |
\(H\) |
airfoil kinematic shape factor |
[-] |
\(I\) |
turbulence intensity |
[-] |
\(k\) |
wave number |
[m-1] |
\(\overline{k},\ \widehat{k}\) |
nondimensional wave number |
[-] |
\({\mathrm{\Delta}K_{1},\ K}_{1}\),\(\ K_{2}\) |
empirical parameters of the BPM model |
[-] |
\(l\) |
spanwise extent of the separation zone from blade tip |
[m] |
\(L\) |
lift force |
[N] |
\(L_{t}\) |
length scale |
[m] |
\(M\) |
Mach number |
[-] |
\(M_{c}\) |
Mach number past the trailing edge |
[-] |
\(r_{e}\) |
effective observer distance |
[m] |
\(\text{Re}\) |
Reynolds number |
[-] |
\(S^{2}\) |
Sears function |
[-] |
\(\text{St}\) |
Strouhal number |
[-] |
\(t_{x}\) |
relative thickness of the airfoil at chordwise position x |
[-] |
\(U\) |
local inflow velocity |
[m/s] |
\(y\) |
blade spanwise position |
[m] |
\(z\) |
height above the ground |
[m] |
\(z_{0}\) |
ground surface roughness |
[m] |