The Effect Of Personal Air Supply On Occupants’ Comfort In Aircraft Cabins In Winter

With the development of civil aviation in our country,more and more people begin to choose to travel by air.As a special environment charactized as high occupants’ detinsity and narrow space,creating a comfortalbe thermal environment of cabin has become the key focus by aircraft manufacturer,research institution and public.Due to the individual difference,the main air distribution system can not satisfy everyone’s comfort demands,for which is offseted by the personal air supply system.However,there is no specific requirement for personal air supply system(PASS)in current standards of thermal environment in aircraft cabin.So our research team investigated the real flights and conducted experiment in our three-row aircraft cabin,and found that the PASS was needed by majority of passengers because its cooling effect in summer.While,in winter they also may open the nozzle to release sense of stuffy or uncomfort.To explore that,this study focus on the air distribution characteristic of nozzle,usage rules and impact on human confort in winter.Firstly,this paper analyzed the research methods and criterions in this study.The mockup three row aircraft cabin built by Chongqing University was introduced in detail.The physical index of human body and measurement methods,the principle of human experiments,methods of the questionnaire designs and how subjects selected were described.Then,the environmental paramters and instruments needed were sepcificed.Secondly,the physical characteristic and usage habits of personal air supply nozzle in winter was stuied.Experimental measurement including: investigating the relationship of air velocity,flesh air and temperature difference between the outlet and huam body using different measurement methods;testing the air velocity and turbulence distribution from the personal air supply and around human body.Conducting an experimental investigation of behavioral response to thermal envirment in aircraft cabin.The experinment was conduct in different conditions with air temperature at 20 oC,22 oC,24 oC and 26 oC.Results shows majority of subjects close nozzle and put on jacket in 20 oC,while open nozzle and take off jacket at 26 oC.The mains reason to open nozzle are stuffy(due to bad air quality about 50%-80%)and warm(due to high temperature,about 30%).The human’s comfort is largely effected by psychological path,thus the human experiment is very important to find out the optimized airflow rate.20 healthy college students were recruited to study the comfortable airflow rate of personal air supply when the cabin temperature at the range of 20 to 28 oC in winter.And other 20 subjects were compared with it in the summer at 26 oC.There are two levels of clothing insulation,one is winter clothing at 28 oC,26 oC,24 oC and 22 oC,the other is winter clothing with jacket at 24 oC,22 oC and 20 oC.The airflow rate has four levels: nozzle closed,0.5 L/s,1.0 L/s and 1.5 L/s.Subjective questionnaire including thermal sensation vote,thermal comfort,draught rate,perceived air quality and so on.At the same time,subjects’ skin temperature was measured.The results show that TSV decreased as airflow rate rising,DR and PAQ increased as the airflow rate risiing.The draught sensation is mainly concentrated in the head;local skin temperatures are affected by various factors in different degrees,the head skin temperature is mainly effect by thermal environment and airflow rate,the skin temperature of chest and upper arm is mainly affected by clothing,and the skin temperature of hand is mainly affected by their body’s thermal state.Analysis of results show subjects are more thermal sensitive to thermal environment in aircaraft cbin than they are in building environment because of psychological factors and limit of adaptive behavior.Compared to other parts of the body,hand skin temperature is more sensitive to the human body thermal state.PAQ is affected by the thermal environment,when the subjects felt slightly warm the PAQ decreased obviously.It is also found that PAQ has a strong linear relationship SET.The traditional Fanger’s draught model does not suitable to the personal air supply environment in this study,so a new DR model is established according to the DR of head base on the heat transfer theory.In conclusion,creating cabin environment should avoid overheating and draught in winter,thus the optimized comfort zone for personal air supply was recommended.