Simulation Research On The Control Of Air Pressure In Oxygen Mask And Oxygen Concentration

When the pilots navigate the advanced aircraft of the modern times aloft in the sky,they usually face the threats such as superaltitude,low air pressure,high overload,low temperature and the other bad environmental factors.Especially when the aircraft is flying at a high altitude,the atmospheric pressure of the surrounding environment reduces extremely and the oxygen deficit becomes one of the most serious threats which the pilots face.Therefore,it is imperative and of great importance to have the perfect equipment and technology to provide suitable and enough oxygen to the pilots stably and reliably.With the development of many advanced technologies such as airborne molecular sieve oxygen generating system,the oxygen supply technology of the low total pressure and the total integrated partial pressure suit,the solution of the oxygen supplying problem has made a great progress.But since that the most advanced aircraft in the contemporary era can fly very fast in the sky and its flight altitude changes sharply and irregularly when it implements some kinds of tactical maneuvers,it brings the new challenges to control the oxygen concentration of the air which is supplied to the pilots boarding on the aircraft.In addition,due to that the air tightness of partial pressure suit's mask is better than the traditional oxygen mask,the pilot's respiration has a great influence to the air pressure in the oxygen mask.It brings a new problem to control the internal pressure of the oxygen mask which the pilot wears.Thus,in order to solve the problem of supplying oxygen to the pilot safely,stably and reliably when he flies an advanced aircraft aloft in the sky,this paper has researched the problem to the control the opening degree of the valve of the breathing adjuster and that to control the air pressure in the mask.The specific research contents and the results are as follows:Firstly,the mathematical model,which describes the relation between the opening degree of the valve of the breathing adjuster and the flight altitude of the aircraft,is firstly set up through analyzing requirement of aviation physiology and working principles of the breathing adjuster.Then a fuzzy controller is designed to control the opening degree of the valve in order to make the breathing adjuster supply to the pilot the mixed gas with suitable oxygen concentration.Finally MATLAB Simulink is employed to verify the feasibility and validity of the fuzzy controlling approach.The results of simulating experiments show that the fuzzy control approach proposed in this paper can make the breathing adjuster supply the mixed gas with suitable oxygen concentration to the pilot boarded on an aircraft.Then this paper also investigates the problem that the air pressure in the oxygen mask of the total integrated partial pressure suit can be easily influenced by thefrequency and depth of the pilot's breathing,the oxygen supplied by the breathing adjuster,its own exhausted air and the other factors.The mathematical model,which describes the problem of controlling the air pressure in the mask,is proposed on basis of analyzing the existed experimental data and according to the principle of fluid mechanics.And then the PID controller is designed to control the internal pressure of mask by adjusting the valve opening degree of the breathing adjuster's inlet.Finally the simulation software EASY5 is employed to design the simulating model of the problem controlling the pressure in the mask and carry out the simulating experiments of controlling the air pressure in the mask through adjusting the valve opening degree of the breathing adjuster's inlet.The experimental results show that the pilot can be ensured to breathe smoothly and safely under the situation of only feeling mild respiratory resistance.Finally,the experimental platform of the controlling system which is designed to adjust the air pressure in the oxygen mask is built with the structural parameters which have been deduced from the simulating experiment mentioned above.Then the experimental platform is applied to carry out the practical experiments and acquire the practical experiment data.By comparing the practical experiment results with that of simulating experiment the results,it proves the correctness of mathematical model and the simulation model about on the problem of controlling the air pressure in the mask.