In order to solve the problems of difficult test, high cost and long cycle in the development of large-scale airborne negative pressure isolation system, the simulation analysis of negative pressure response characteristics is carried out around various aviation conditions such as aircraft ascending, leveling and descending, especially rapid decompression, based on the computational fluid dynamics (CFD) method. The results showed that the isolation cabin could achieve -50 Pa pressure difference environment and form a certain pressure gradient. The exhaust air volume reached the maximum value in the early stage of the aircraft's ascent, and gradually decreased with the increase of altitude until it was level flying. In the process of aircraft descent, the exhaust fan could theoretically maintain a pressure difference far below -50 Pa without working; Under the special condition of rapid pressure loss, it was difficult to deal with the rapid change of low pressure only by the exhaust fan, so it was necessary to design safety valve and other anti-leakage measures in the isolation cabin structure. Therefore, the initial stage of aircraft ascent is the key stage for the adjustment and control of the negative pressure isolation system. By controlling the exhaust air volume and adjusting parameters, it can adapt to the change of low pressure under normal flight conditions, form a relatively stable negative pressure environment, and meet the needs of biological control, isolation and transport.
Aircraft ; Computer Simulation ; Aviation/instrumentation* ; Humans ; Hydrodynamics ; Air Pressure ; Equipment Design ; Pressure

AIMTo assess the +Gz protection afforded by an advanced bladder anti-G system in the centrifuge against a capstan anti-G system.

METHODSTow centrifuge experiments were completed, respectively, by two groups of six male subjects. In the first experiment, subjects using advanced bladder anti-G system, the +Gz protection afforded by this anti-G system was determined. Then they were exposed to simulated air combat maneuver (SACM)I with leg straining, the +Gz-time tolerance was determined. In the second experiment, subjects using capstan anti-G system, the +Gz protection afforded by this anti-G system was determined. Then they were exposed to SACMII with anti-G straining maneuver, the +Gz-time tolerance was determined.

RESULTSThe anti-G effectiveness of the advanced bladder system was 5.33 G, which was significantly higher than that of the capstan system by 1.35 G (P < 0.01). All subjects of the two groups passed themselves SACM, but the effort, fatigue, and heart rates of the first group subjects were lower than those of the second group subjects.

CONCLUSIONThe results demonstrate that the +Gz protection afforded by the advanced bladder anti-G system is significantly higher than that by the capstan system.

Adult ; Aerospace Medicine ; instrumentation ; Aviation ; instrumentation ; Centrifugation ; instrumentation ; Equipment Design ; Gravity Suits ; Humans ; Male ; Physical Endurance ; physiology ; Young Adult