According to the shearing force character and the deformation coordination condition of shell at the station of supports, the mathematical models to calculate contact angle and contact pressure distribution between ty...According to the shearing force character and the deformation coordination condition of shell at the station of supports, the mathematical models to calculate contact angle and contact pressure distribution between tyre and shell were set up, the formulae of bending moment and bending stress of tyre were obtained. Taking the maximum of tyre fatigue life as the optimal objective, the optimization model of tyre support angle was built. The computational results show that when tyre support angle is 30°, tyre life is far less than that when tyre support angle is optimal, which is 35.6°, and it is unsuitable to stipulate tyre support angle to be 30° in traditional design. The larger the load, the less the nominal stress amplitude increment of tyre, the more favorable the tyre fatigue life when tyre support angle is optimal.展开更多
应用Realizable k-ε湍流模型和VOF(Volume of Fraction)两相流模型对某压力旋流喷嘴进行数值研究,分析了旋流室锥角、旋流孔角度及喷嘴入口压力变化对雾化锥角、雾化粒径及分布、液滴速度分布等参数的影响。结果表明:雾化锥角受旋流室...应用Realizable k-ε湍流模型和VOF(Volume of Fraction)两相流模型对某压力旋流喷嘴进行数值研究,分析了旋流室锥角、旋流孔角度及喷嘴入口压力变化对雾化锥角、雾化粒径及分布、液滴速度分布等参数的影响。结果表明:雾化锥角受旋流室锥角的影响幅度随压力增大而减小,雾化粒径及分布受旋流室锥角影响不明显,当旋流室锥角为90°时雾化范围广且雾化稳定性好;雾化锥角随旋流孔角度增大先增后减,当角度为45°时雾化锥角最大,平均粒径及其分布更佳;当喷嘴入口压力逐渐增大时,雾化锥角与雾化粒径均逐渐减小,液滴速度区间逐渐缩小,当入口压力达到0.4 MPa时,Sauter粒径及液滴粒径分布趋于稳定,液滴速度分布最为集中。展开更多
针对先进高性能飞行器对高精度大气数据的测控需求,研发设计了一套适用于亚声速飞行器的嵌入式大气数据传感(flush air data sensing,FADS)系统。该系统首先基于数值建模技术建立了FADS系统模型的压力数据库,并针对建模数据精度及风洞...针对先进高性能飞行器对高精度大气数据的测控需求,研发设计了一套适用于亚声速飞行器的嵌入式大气数据传感(flush air data sensing,FADS)系统。该系统首先基于数值建模技术建立了FADS系统模型的压力数据库,并针对建模数据精度及风洞试验校准数据分析了Ma=0.2~0.4对应的压力误差限;其次,开发了攻角实时解算算法,并集成到工程原理样机中;最后基于风洞试验和飞行试验对FADS系统的实时解算算法及样机进行了系统评估,并通过事后模型算法对攻角进行重新解算以评估攻角实时解算算法的可靠性。结果表明:(1)与机载惯性导航系统等其他独立测试系统解算的数据相比,飞行试验中FADS系统采用的攻角实时解算方法精度整体较好,攻角误差小于1°,在关键段小于0.5°;基于不同模型建立的FADS系统攻角解算方法得到的攻角数值基本一致,证实了开发的实时解算算法的可靠性。(2)基于风洞试验及飞行试验数据对算法误差限的考核结果显示,飞行试验初始阶段实时解算的攻角值产生波动是压力输入波动误差限较大造成的,高空低速时的压力波动幅值大是实时解算攻角值偏差较大的主要原因;建立的FADS系统的攻角解算方法在算法误差限范围内的压力波动对攻角解算值影响较小,但超过算法误差限的压力波动对攻角解算值影响显著。高空低速飞行器FADS系统对测压传感器精度水平及工程实施水平要求较高,在实际工程应用中应尽量保证测压传感器的精度水平。展开更多
基金Project(2005038227) supported by the China Postdoctoral Science Foundation project(04JJ3050) supported by the Hu-nan Natural Science Foundation
文摘According to the shearing force character and the deformation coordination condition of shell at the station of supports, the mathematical models to calculate contact angle and contact pressure distribution between tyre and shell were set up, the formulae of bending moment and bending stress of tyre were obtained. Taking the maximum of tyre fatigue life as the optimal objective, the optimization model of tyre support angle was built. The computational results show that when tyre support angle is 30°, tyre life is far less than that when tyre support angle is optimal, which is 35.6°, and it is unsuitable to stipulate tyre support angle to be 30° in traditional design. The larger the load, the less the nominal stress amplitude increment of tyre, the more favorable the tyre fatigue life when tyre support angle is optimal.
文摘应用Realizable k-ε湍流模型和VOF(Volume of Fraction)两相流模型对某压力旋流喷嘴进行数值研究,分析了旋流室锥角、旋流孔角度及喷嘴入口压力变化对雾化锥角、雾化粒径及分布、液滴速度分布等参数的影响。结果表明:雾化锥角受旋流室锥角的影响幅度随压力增大而减小,雾化粒径及分布受旋流室锥角影响不明显,当旋流室锥角为90°时雾化范围广且雾化稳定性好;雾化锥角随旋流孔角度增大先增后减,当角度为45°时雾化锥角最大,平均粒径及其分布更佳;当喷嘴入口压力逐渐增大时,雾化锥角与雾化粒径均逐渐减小,液滴速度区间逐渐缩小,当入口压力达到0.4 MPa时,Sauter粒径及液滴粒径分布趋于稳定,液滴速度分布最为集中。
文摘针对先进高性能飞行器对高精度大气数据的测控需求,研发设计了一套适用于亚声速飞行器的嵌入式大气数据传感(flush air data sensing,FADS)系统。该系统首先基于数值建模技术建立了FADS系统模型的压力数据库,并针对建模数据精度及风洞试验校准数据分析了Ma=0.2~0.4对应的压力误差限;其次,开发了攻角实时解算算法,并集成到工程原理样机中;最后基于风洞试验和飞行试验对FADS系统的实时解算算法及样机进行了系统评估,并通过事后模型算法对攻角进行重新解算以评估攻角实时解算算法的可靠性。结果表明:(1)与机载惯性导航系统等其他独立测试系统解算的数据相比,飞行试验中FADS系统采用的攻角实时解算方法精度整体较好,攻角误差小于1°,在关键段小于0.5°;基于不同模型建立的FADS系统攻角解算方法得到的攻角数值基本一致,证实了开发的实时解算算法的可靠性。(2)基于风洞试验及飞行试验数据对算法误差限的考核结果显示,飞行试验初始阶段实时解算的攻角值产生波动是压力输入波动误差限较大造成的,高空低速时的压力波动幅值大是实时解算攻角值偏差较大的主要原因;建立的FADS系统的攻角解算方法在算法误差限范围内的压力波动对攻角解算值影响较小,但超过算法误差限的压力波动对攻角解算值影响显著。高空低速飞行器FADS系统对测压传感器精度水平及工程实施水平要求较高,在实际工程应用中应尽量保证测压传感器的精度水平。
