List of symbols

Symbol	Name of the symbol	Unit
$d_1$	diameter $ d_1 $	$\mathrm{mm}$
$d_2$	diameter $ d_2 $	$\mathrm{mm}$
$f$	friction factor	$\mathrm{ }$
$l$	length	$\mathrm{mm}$
$α$	angle	$\mathrm{°}$
$β$	diameter ratio	$\mathrm{ }$
$ζ$	loss coefficient	$\mathrm{ }$
$μ$	discharge coefficient	$\mathrm{ }$
$φ_0$	coefficient $ φ_0 $	$\mathrm{ }$