Wave vector measurements of empirical design transfer functions Free

Empirical design transfer functions can be used to predict the radiated noise generated from various components in a system. The Darby method is one example of an approach used to find these empirical design transfer functions. For an immersed and radiating structure, near‐field measurements of the pressure field can be wave vector filtered to find the empirical design transfer function from the structural input point to the acoustic far field. Assuming a cylindrical body excited by a force and radiating, a discrete line array of pressure sensing devices are used to measure the near‐field pressure. The acoustic pressure data measured at each point are sampled, digitized, time averaged, and frequency transformed. The position‐frequency domain pressure is then transformed into the wave vector domain, and the far‐field radiation is predicted. The empirical design transfer function is found by dividing the predicted far‐field radiation by the input force. The mathematical development of this approach is presented. Simulations are presented for various radiation sources, including a monopole and a discrete line source. The pressure predictions of the wave vector are compared with the pressure directly computed for the sources. [Work supported by ONR.]