such a mesh screen can easily be introduced in the embodiments of the invention described in fig5 as an example fig6 shows a mesh screen 22 attached to the inner wall of the air duct 16 covering all of the exit of the duct 20 from the nozzle 2 to the air duct 16 except for the entrance 7 to the return tube 6 in that way all the drops of the jet that enter the air duct 16 are broken up into much smaller drops except those that enter the return tube at the same time their speed is reduced so that they can be carried away by the air stream into the engine more efficiently preferably the mesh screen should be made of metal wire mesh with about 2 5 wires per millimeter but also wider or smaller mesh sizes can be used alternatively a small slit may be used instead of the mesh screen in the embodiment shown in fig5 the mesh screen is attached to the lower opening of the duct 20 where the jet exits into the air tube 16 however the mesh may be positioned at other places along the jet path as described above the undeflected jet enters the return tube 6 with an appreciable speed in this process a certain amount.