Industrial Research Ltd, PO Box 31-310, Lower Hutt, New Zealand.
J Acoust Soc Am. 2011 Jun;129(6):3513-20. doi: 10.1121/1.3589481.
A spherical harmonic expansion for the sound field due to a rotating oscillating point source has recently been derived. This paper provides further confirmation of the expansion results by comparing it with two known numerical approaches to determining the sound field. In the advanced time approach-applicable for Mach numbers below 1-the sound at transmission time determines the field at an observation point from the distance from source to observation point at the transmission time. In the retarded time approach the field at the observation point at the observation time is determined by solving for the retarded transmission times. The results from all three approaches are shown to be in good agreement. Expressions for the far-field instantaneous frequency are also derived and shown to agree with previous work.
最近导出了一个旋转振荡点源声场的球谐展开式。本文通过将其与两种已知的声场确定数值方法进行比较，进一步验证了展开结果。在先进的时间方法（适用于马赫数低于 1 的情况）中，在传输时间的声音确定了在传输时间从声源到观察点的距离处观察点处的场。在延迟时间方法中，通过求解延迟传输时间来确定观察时间处观察点的场。所有三种方法的结果都显示出很好的一致性。还推导了远场瞬时频率的表达式，并与以前的工作一致。
