3. Characteristics of an electro-pneumatic power modulator

3.1 Compressible fluid flow laws

An electro-pneumatic power modulator controls gas energy transfer by driving variable-area orifices.

For compressible fluids, the mass flow through each passage section is a function of the pressures upstream and downstream of the section in question. ISO 6358-1989 proposes a mathematical approximation of the laws of flow through a fixed restriction using two parameters:

• the sonic conductance C, expressed in m ³ · s ^–1 · Pa ^–1 , the image of the effective cross-sectional area of the component determined in the sonic regime;

• ...