Pitou type probe for flow velocity registration with possibility of independent temperature control

Abstract
Proposed control equipment scheme is based on acoustic Helmholtz resonator property to change its resonance frequency when sound speed in the vicinity of its throat inlet is changed. So this kind of resonator with pressure measuring acoustic transducer is installed in well known Pitou probe static pressure volume envelope, slightly changing its construction. To use Pitou probe of new type, except of difference between dynamic and static pressure conventional measurement, one must additionally control acoustic pressure spectrum maximum frequency observed in resonator volume by means of spectrum analyzer or other frequency measuring device connected to transducer. Graduation curves for Helmholtz resonator frequency are presented showing that resonance frequency change is linearly dependent on sound speed change and - by square root law - on temperature change. Initial experimental results conducted in model circumstances (in air) are presented giving possibility to estimate effect of measuring equipment proposed.