Converging-Throat-Chamber Nozzle

$fn = 150; total_length = 50.0; outer_diameter = 16.0; inlet_length = 8.0; // smooth accelerating taper into throat inlet_start_dia = 16.0; throat_dia = 2.0; throat_length = 2.0; // just enough to stabilize the jet chamber_length = total_length - inlet_length - throat_length; // 40.0 mm chamber_dia = 10.0; difference() { cylinder(h = total_length, d = outer_diameter, center = false); union() { translate([0, 0, -0.01]) cylinder(h = inlet_length + 0.01, d1 = inlet_start_dia, d2 = throat_dia); translate([0, 0, inlet_length]) cylinder(h = throat_length + 0.01, d = throat_dia); translate([0, 0, inlet_length + throat_length]) cylinder(h = chamber_length + 0.05, d = chamber_dia); } }

Parameters

Every value above is a live dimension. Open a model like this in the editor and each one becomes a slider you can drag before exporting.