Reusable helical filter for high temperature gases

Abstract

A reusable filter to remove contaminants from high temperature gases, in excess of 4500.degree. F., developed by burning propellants and used to do work such as actuation of piston-powered devices in aircraft store ejector racks. Contaminants are removed to prevent fouling of the device being acted upon. The filter has a metal strip wound in the form of a helix, the turns of the helix being spaced from one another to permit side entry of the gas between the turns. Protuberances spaced along one side of the strip establish filter gaps between the turns. A closed, convoluted structural support runs through the center of the helix from one end to the other of the filter in order to support the shape of the helix. The convoluted structural support also defines a plurality of axial flow passages between its closed surface and the helix, the passages communicating with the filter gaps to allow axial gas flow along the inside of the filter for end exit. The metal strip and structural support are both made of molybdenum, columbium or tantalum. Studs pass through the interior of the convoluted structural support to hold the filter together. Filtering gaps in an axial direction between adjacent turns of the helix may be of the order of a few microns to a few hundred microns.