Tham khảo tài liệu 'compressor instability with integral methods episode 1 part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 3 Air and Abrasive Acceleration Properties of Compressed Air Air is a colourless odourless and tasteless gas mixture. It consists of many gases but primarily of oxygen 21 and nitrogen 78 . Air is always more or less contaminated with solid particles for example dust sand soot and salt crystals. Typical properties of air are listed in Table . If air is considered to be an ideal gas its behaviour can be described based on the general law of state p US Ri T where p is the static air pressure US is the specific volume of the gas Ri is the individual gas constant and T is the absolute temperature. It can be distinguished between three pressure levels which are illustrated in Fig. . The relationships between these pressure levels are as follows p p0 pG The parameter p is the absolute pressure the parameter pG is the gauge pressure usually read by the pressure gages in the blast cleaning pressure systems and the parameter p0 is the atmospheric pressure. The atmospheric pressure is a function of altitude. It is important not to confuse the absolute pressure and the gauge pressure. For theoretical calculations the absolute pressure must be used. The parameter Ri in is the individual gas constant which is the energy delivered by a mass of 1 kg of air if its temperature is increased by 1 C K at constant pressure. Its value for air is provided in Table . The individual gas constant is the difference between isobaric heat capacity and isochoric heat capacity of the gas Ri cp - cv The ratio between isobaric heat capacity and isochoric heat capacity is the isentropic exponent of the gas cP K cV A. Momber Blast Cleaning Technology Springer 2008 55 56 3 Air and Abrasive Acceleration Table Properties of air Parameter Symbol Unit Value Densitya Pa kg m3 Dynamic viscositya fi0 Ns m2 X 10-5 Isobaric specific heat capacityb Cp Nm kg K 1 004 Isochoric specific heat capacityb CV Nm kg K 717 Gas constant ft Nm kg K 287 Adiabatic .
