Structural Endurance Stand Tests of the Gas Turbine and Axial Compressor Rotor Blades of Stationary Gas Turbine Units

Structural endurance testing of rotor blades is the most important stage of perfecting newly developed blade systems for gas turbine units (GTUs). Obtaining the values of a blade’s structural endurance (fatigue) limit allows designers to evaluate the vibration reliability of a GTU’s blade system. Experimental data also provide an opportunity to verify calculated models of blades. Specialists at the Power Machines company are now working on a line of new GTUs that includes the GTE-170 gas turbine unit. The rotor blades of the GTE-170 unit’s axial compressor and gas turbine, manufactured according to original equipment design documents, are currently being studied for structural endurance on the TsKTI Research and Production Association (NPO) fatigue testing stand. Blade vibration is excited on the stand by applying a variable-frequency electromagnetic field to the area around the tip of a blade. The blade’s limit of structural endurance is determined proceeding from the readings from strain gauges glued in the zones of maximum vibration stresses. Fatigue tests of more than 300 blades used in 14 stages of axial compressors and four gas turbine stages have been run on the stand. The resulting data show that the rotor blades of the GTE-170 unit’s axial compressor and gas turbine have high vibration reliability. Based on results from comparative fatigue tests, it has been determined how replacing the grade of steel and redesigning a blade’s profile affect its vibrational strength. Stand test results have confirmed the need to perform experimental studies of the structural endurance of both newly developed and updated blades when changing their material and redesigning their profiles.