Accurate cavity volume testing based on micropressure differential gas inflation and deflation

Abstract

For cavity volume testing, conventional optical or acoustic direct test methods are not only limited in terms of measurement efficiency, but also have difficulty avoiding errors due to complex cavity structures. In this paper, we present a cavity volume test based on micropressure differential gas inflation and deflation. The principle of the method is to charge and deflate the test cavity and obtain a mapping between the microbe difference and the inflating flow rate. Variability curves of the pressure difference inside and outside the cavity are measured during the deflating process and the cavity volume is calculated using parameters such as the intake flow rate and differential pressure. The heat and mass transfer equations are formulated for the gas in the cavity under inflation and deflation conditions. Numerical simulations of the variability of the gas state parameters and their impact factors are performed to verify the feasibility of the volumetric measurements. An experimental setup for volume measurements is constructed and a cockpit is used as an application object for volume measurement experiments under different micropressure differential inflation and deflation conditions. It shown that, as a complement to geometrical physical measurements, this method can better characterize the gas volume of the cavity.