STRAIN MEASUREMENT IN TURBINE ENGINES

THE PROPOSED RESEARCH WILL TEST THE FEASIBILITY OF REMOTELY MEASURING MECHANICAL STRAIN IN HOSTILE ENVIRONMENTS AND ON MOVING ENGINE PARTS OR OTHER STRUCTURES USING A SPECIAL LOW LEVEL RADIATION SOURCE PRODUCED BENEATH THE SURFACE. STRAIN ON THE PART IN QUESTION WILL CHANGE THE ATTENUATION OF SURFACE MATERIAL COVERING THE SOURCE AND THUS CHANGE THE RELAYED SIGNAL WHICH IS ULTIMATELY MONITORED BY A DETECTOR EXTERNAL TO THE ENGINE. CHANGES IN STRAIN THEN PRODUCE CORRESPONDING CHANGES IN COUNTING RATE AT THE DETECTOR. BECAUSE OF THE DESIGN FOR SUCH A STRAIN GAUGE, THE SENSOR SHOULD BE SUITABLE FOR HIGH TEMPERATURES AND WILL NOT INTERFERE WITH FLOW BECAUSE IT DOES NOT PROTRUDE INTO THE STREAM, OR CHANGE THE SURFACCE SHAPE IN ANY WAY. ONLY THE EXTERNAL DETECTOR SYSTEM WOULD REQUIRE ELECTRICAL CONNECTIONS AND NO PENETRATING WIRES OR ELECTRICAL FEEDTHROUGH WOULD BE NEEDED. A SMALL CORRECTION FOR TEMPERATURE CHANGES, AS IS ALSO REQUIRED BY CONVENTIONAL STRAIN GAGUES, MAY BE NECESSARY. THIS TYPE OF GAUGE WOULD BE IDEAL FOR MONITORING STRAIN ON MOVING PARTS, FOR EXAMPLE, IN OPERATING TURBINE ENGINES. RAPIDLY OF MEAUSRMENT WOULD BE A FUNCTION OF SOURCE STRENGTH, BUT QUITE MODEST SOURCES WHICH DO NOT INVOLVE ANY HAZARD OR SPECIAL HANDLING COULD PRODUCE RELIABLE MEASUREMENTS EVERY 10 TO 20 SECONDS.