The speed of sound of the gaseous difluoromethane (HFC-32) and trifluoroiodomethane(CF3I) are measured with a cylindrical, variable-path acoustic interferometer operating at156.252 kHz. Temperatures ranged from 273.15...The speed of sound of the gaseous difluoromethane (HFC-32) and trifluoroiodomethane(CF3I) are measured with a cylindrical, variable-path acoustic interferometer operating at156.252 kHz. Temperatures ranged from 273.15 K to 333.15 K for both and pressures rangedfrom 48 kPa to 390 kPa for HFC-32 and from 58 to 276 kPa for CF3I, respectively Theuncertainty of the speed of sound was less than ±0.1%. The ideal-gas heat capacity atconstant pressure and the second acoustic virial coefficients for HFC-32 and CF3I werealso determined over the temperature range from the speed of sound measurements. Theideal-gas heat capacities at constant pressure and second virial coefficients calculated fromthese speed of sound measurements for both were compared with results from the literaturedetermined from PVT measurements and from speed of sound measurements, respectively.The uncertainty of the ideal-gas heat capacities at constant pressure were estimated to beless than ±1%.展开更多
High-temperature effects alter the physical and transport properties of air such as vibrational excitation in a thermally perfect gas,and this factor should be considered in order to compute the flow field correctly.H...High-temperature effects alter the physical and transport properties of air such as vibrational excitation in a thermally perfect gas,and this factor should be considered in order to compute the flow field correctly.Herein,for the thermally perfect gas,a simple method of direct numerical simulation on flat-plat boundary layer is put forward,using the equivalent specific heat ratio instead of constant specific heat ratio in the N-S equations and flux splitting form of a calorically perfect gas.The results calculated by the new method are consistent with that by solving the N-S equations of a thermally perfect gas directly.The mean flow has the similarity,and consistent to the corresponding Blasius solution,which confirms that satisfactory results can be obtained basing on the Blasius solution as the mean flow directly in stability analysis.The amplitude growth curve of small disturbance is introduced at the inlet by using direct numerical simulation,which is consistent with that obtained by linear stability theory.It verified that the equation established and the simulation method is correct.展开更多
文摘The speed of sound of the gaseous difluoromethane (HFC-32) and trifluoroiodomethane(CF3I) are measured with a cylindrical, variable-path acoustic interferometer operating at156.252 kHz. Temperatures ranged from 273.15 K to 333.15 K for both and pressures rangedfrom 48 kPa to 390 kPa for HFC-32 and from 58 to 276 kPa for CF3I, respectively Theuncertainty of the speed of sound was less than ±0.1%. The ideal-gas heat capacity atconstant pressure and the second acoustic virial coefficients for HFC-32 and CF3I werealso determined over the temperature range from the speed of sound measurements. Theideal-gas heat capacities at constant pressure and second virial coefficients calculated fromthese speed of sound measurements for both were compared with results from the literaturedetermined from PVT measurements and from speed of sound measurements, respectively.The uncertainty of the ideal-gas heat capacities at constant pressure were estimated to beless than ±1%.
基金supported by the National Nature Science Foundation of China(Grant Nos.11172203 and 91216111)the National Basic Research Program of China(Grant No.2009CB724103)
文摘High-temperature effects alter the physical and transport properties of air such as vibrational excitation in a thermally perfect gas,and this factor should be considered in order to compute the flow field correctly.Herein,for the thermally perfect gas,a simple method of direct numerical simulation on flat-plat boundary layer is put forward,using the equivalent specific heat ratio instead of constant specific heat ratio in the N-S equations and flux splitting form of a calorically perfect gas.The results calculated by the new method are consistent with that by solving the N-S equations of a thermally perfect gas directly.The mean flow has the similarity,and consistent to the corresponding Blasius solution,which confirms that satisfactory results can be obtained basing on the Blasius solution as the mean flow directly in stability analysis.The amplitude growth curve of small disturbance is introduced at the inlet by using direct numerical simulation,which is consistent with that obtained by linear stability theory.It verified that the equation established and the simulation method is correct.
