SENSOR ARRAY DESIGN FOR WAVE DECOMPOSITION IN THE PRESENCE OF COUPLED MOTION

The estimation of wave amplitudes is investigated for the case in which two different vibration types couple to the measured variables. Particular reference is made, by way of example, to the coupling of axial wall motion to pressure waves in a fluid-filled pipe. Two different types of sensor array are considered: one in which the same parameter is measured at a number of different locations, and one in which the measured parameters are not all identical. Predictions of variation in frequency range and sensitivity to measurement errors are made based on the behaviour of the determinant of the transformation matrix, and are verified by simulation. It is shown that the analytical expression for this determinant can give valuable insight into the design of sensor arrays, and that the choice of measured variables is critical to achieving low sensitivity to measurement error.