| Recent advances in turbomachinery design have led to the use of monolithic bladed disks (blisks) for their increased overall aerodynamic efficiency and decreased drag, complexity, parts count, and weight. However, these improvements come at the cost of very low intrinsic damping, resulting in large vibratory stresses and ultimately leading to high-cycle fatigue. This research aims at the development of a technique that reduces the turbomachinery blade vibration generated when a change in rotation speed results in an excitation frequency sweeping through a structural resonance frequency. In particular, a semi-active technique termed resonance frequency detuning is developed, simulated, and experimentally demonstrated to illustrate its potential for turbomachinery blade vibration reduction.;Resonance frequency detuning involves altering the blade structural properties to avoid (to the extent possible) resonance excitation, thus inhibiting large vibration response. Through the inclusion of piezoelectric material in the turbomachinery blade, detuning alters the electrical boundary conditions of the piezoelectric material to change the blade stiffness. When switched optimally, this change results in a structural resonance frequency that is detuned from that of the excitation.;To achieve optimal vibration reduction, the piezoelectric material should be located in a region of high modal strain, so a significant aspect of this research is the development of an accurate low-order turbomachinery blade model, treated here as a representative at trapezoidal plate with attached piezoelectric material. Based on the assumed modes method, the model produces a set of discretized equations of motion that may be coupled with those corresponding to piezoelectric shunt circuitry to simulate a variety of vibration reduction approaches.;Experimental data validates both the low-order model and the concept of resonance frequency detuning. The model generates very good predictions of plate natural frequencies with a variety of electrical boundary conditions. It also predicts key plate modal parameters like electromechanical coupling coefficients and damping ratios with moderately good accuracy. More significantly, experimental data confirm that resonance frequency detuning can reduce the vibration associated with sweep excitation passing through resonance. Furthermore, the dynamics model can accurately predict the optimal parameters for implementation of resonance frequency detuning, as well as the expected ensuing vibration reduction. |
