Detailed on-Blade Measurements on a Transonic Fan in Unstalled Supersonic Flutter

摘要

Measurements were made on a transonic fan vibrating in a coupled flutter mode. Blades were instrumented with strip transducers, which cover a small area in detail, and others with discrete tranducers, which give general chordwise coverage. Steady and unsteady pressures for the two types of transducer are superimposed to give a more detailed picture. Results are compared with predictions from a finite element potential flow method. The general agreement is good if allowance is made for known assumptions in the theoretical method. The modeshape of the fan in its flutter mode was measured by tip FM grids and holography. Results are compared with the structural finite element model. The measured modeshape and unsteady pressure data are combined to produce unsteady work for a given blade section. This is presented as a function of radius by combining the results of several tests. A unit known as PRESSTEL (pressure telemetry) permitted the simultaneous collection of a larger quantity of data and avoided the need to combine data from several runs and builds, thus improving the overall measurement accuracy.