Reconstruction of Transient Acoustic Radiation From Impulsively Accelerated Objects

The HELS method (Wu, 2000) is extended to reconstruction of transient acoustic radiation from an impulsively accelerated object. The temporal acoustic pressure field is reconstructed by taking an inverse Fourier transformation of the acoustic pressure in the frequency domain. The infinite integral is replaced by a contour integral and evaluated using the residue theory. The formulations thus derived are valid for a spherical surface with an arbitrary normal velocity distribution. These formulations are used to reconstruct the normal surface velocities and transient acoustic fields generated by explosively expanding sphere, impulsively accelerating sphere, and impulsively accelerating baffled sphere. Results show that satisfactory reconstruction can be obtained with relatively few measurements taken around the object under consideration.