充装量及筒体长度对车载LNG气瓶共振频率影响的数值模拟分析

以大容积车载液化天然气(LNG)气瓶为研究对象，分析不同充装量和不同筒体长度下的各阶共振频率随这两个参数变化的规律。当筒体长度不变时，随着充装量的增加，气瓶共振频率逐渐减小，按照标准最大允许充装率90%时，气瓶一阶共振频率已减小到国标允许的40 Hz以下，使用时容易引起气瓶内胆轴向窜动引发失效。当充装率90%保持不变时，随着筒体长度的增加，气瓶共振频率也呈现减小的趋势，当筒体长度为原长的0.8倍时，气瓶共振频率便低于40 Hz，而且随着长度增加将进一步降低，产生共振可能性加大，不满足国家对车载气瓶共振频率的要求。上述研究说明，评价气瓶抗振性能时应考虑内部介质充装率的影响，建议采用最大充装率为90%的气瓶作为判定该类型气瓶共振频率是否达标的条件。另一方面，当采用增加筒体长度扩大盛液容积时要注意共振频率随筒体长度降低的问题，避免结构振动破坏。

Numerical simulation analysis of influence of filling amount and length of cylinder on resonance frequency of vehicle LNG cylinder

Taking the large-capacity liquefied natural gas (LNG) gas cylinder as the research object, the variation of the resonance frequency under different filling amount and different cylinder length with these two parameters is analyzed. When the length of the cylinder is constant, as the filling amount increases, the resonance frequency of the cylinder gradually decreases. When the maximum allowable filling rate is 90% according to the standard, the first-order resonance frequency of the cylinder has been reduced to below 40 Hz allowed by the national standard. When used, it is easy to cause axial collapse of the cylinder liner to fail. When the filling rate is 90%, the resonance frequency of the cylinder also decreases with the increase of the length of the cylinder. When the length of the cylinder is 0.8 times of the original length, the resonance frequency of the cylinder is lower than 40 Hz. As the length increases, it will be further reduced, and the possibility of resonance will increase, which does not meet the national requirements for the resonance frequency of the vehicle cylinder. The above results showed that the evaluation of the internal medium filling ratio should be considered when evaluating the anti-vibration performance of the cylinder. It is recommended to use a cylinder with a maximum filling rate of 90% as a condition for determining whether the resonance frequency of the cylinder is up to standard. On the other hand, when increasing the volume of the cylinder to increase the volume of the liquid, it is necessary to pay attention to the problem that the resonance frequency decreases with the length of the cylinder to avoid structural vibration damage.