Abstract
When the characteristic dimension of a cavity is much greater than the thickness of the thermal boundary layer (δ) the acoustic conductance of the cavity is proportional to the inner surface area of that cavity. On this principle the surface area of an object can be known by measuring the acoustic impedance of the container in which the object is placed. For cavities of the smaller characteristic dimension, however, the acoustic conductance is not accurately proportionate to the cavity surface area since the effect of edges and corners comes to be not negligible. The distributions of acoustically caused temperature variation about edges and corners were investigated numerically. And the edge correction-the equivalent extension of the length and the width of the object in the acoustical surface area measurement-was calculated and found to be 0.6δ. The corner correction-the equivalent reduction of the length of the wall-was also calculated and turned out to be -1.28δ.
