Jet velocity measuring apparatus

A jet velocity measuring apparatus for measuring the velocity of a fluid stream, said apparatus measuring the time delay between primary electronic signals generated by a firsst photosensitive device as a result of a first beam of light from a light source being reflected by a portion of the surface of the stream and secondary electronic signals generated by a second photosensitive device as a result of a second beam of light from a light source being reflected downstream by substantially the same portion of the surface of the stream, said apparatus comprising in combination:

• a housing disposed adjacent to the fluid stream, said housing having a first face;
• a first bifurcated fiberoptic bundle secured to said housing adjacent to said first face for transmitting the first beam of light from the light source to the portion of the surface of the stream and back towards the first photosensitive device;
• a second bifurcated fiberoptic bundle secured to said housing and terminating adjacent to said first face and downstream relative to said termination of said first fiberoptic bundle, said second fiberoptic bundle transmitting the second beam of light from the light source to substantially the same portion of the surface of the stream when this portion of the surface of the stream has flowed downstream away from the first beam of light, said second fiberoptic bundle transmitting the reflected second beam of light back along said second fiberoptic bundle towards the second photosensitive device;
• debris deflecting means disposed adjacent to said first face of said housing for deflecting debris from said first face of said housing thereby inhibiting accumulation of debris on said first face which could otherwise impede transmission of the first and second beams of light towards and away from the fluid stream;
• said respective terminations of said first and second fiberoptic bundles being elongate in a direction transverse relative to the direction of flow of the fluid stream such that misalignment of said terminations of said first and second fiberoptic bundles relative to the direction of flow of the fluid stream results in substantially no variation between the respective signals generated by the first and second photosensitive devices;
• and
• said portion of the surface of the stream adjacent to said first bifurcated fiberoptic bundle having a surface area the same as said portion of the surface of the stream adjacent to said second bifurcated fiberoptic bundle due to said elongate configuration of said respective fiberoptic bundles even when the disposition of said fiberoptic bundles are misaligned relative to said direction of flow of said fluid stream.