In order to meet the accurate measurement of air flow under the low flow intake conditions of the engine high-altitude test

reduce the influence of the air flow surface layer in the intake duct

and weaken the correlation between the air flow measurement and the tested engine

the working characteristics of the single piece/combined critical flow Venturi nozzle (CFVN) were analyzed

and the calculation method of the air flow of the array of critical flow Venturi nozzle (ACFVN) was expounded. The calculation method of combined CFVN was also given. The combination structure was designed according to the given test engine and the size of the high-altitude cabin. The control method and test layout of the combined CFVN in high-altitude cabin were obtained. The design and application methods of the combined nozzles were verified by small-sized nozzles. The results show that the method of opening and closing the nozzles and adjusting the intake pressure could be applied in the high-altitude cabin

the test layout meets the measurement requirements

and the Turbulence of engine intake flow is better than 0.3%

meeting the requirements of engine high altitude simulation test.