nozzle having an upstream face which consists of a flat surface perpendicular to the nozzle axis, a convergent section the shape of which is a quarter ellipse, a cylindrical throat and possible a resess or a bevel, düüs, millel on voosisendpind, mis koosneb düüsi teljega risti olevast tasapinnast, veerandellipsi kujulise profiiliga koonduvast sektsioonist ja silindrilisest avast