Computer modeling and functional evaluation of Venturi flow generators for use in ventilators

A Venturi has been traditionally used for liquid and gas flow measurements based on Bernoulli and Venturi principles. Application of Venturi as a flow generator in a mechanical ventilator was limited to being a secondary source of flow or configured to compress flexible bags. The main reason for this level of utilization is the considerable flow deterioration of flow output under respiratory system load. A method was hence sought to probe into the possibility of using a Venturi device as the main flow generator with onload flow compensation. The Venturi was mathematically modeled to incorporate the three possible control variables which are controls of jet diameter, entrainment port size and the working pressure of the gas to be entrained. A set of experimental data were then quantitatively compared and evaluated with the results of computer simulation of the TUTSIM model of the system under equivalent conditions. The nature of the results can open up a range of different automatic control schemes and their practical implementation.