筒壁沟槽式制退机主流液压阻力系数分析

Mainstream hydraulic resistance coefficient of a cylinder wall groove recoil mechanism

液压阻力系数k_1是反映主流流道结构特征的参数,是火炮制退机设计的关键,相似流道结构特征时可参考取值,而不同流道结构时取值范围相差较大。针对某筒壁沟槽式制退机,为了确定合理的k_1取值范围,对其影响参数、变化规律进行了研究。通过筒壁沟槽式制退机主流流道特征进行分析,经合理简化,将活塞杆固定,设定入口边界流速V＇模拟制退杆后坐运动速度V,出口边界为自由流出,在Fluent软件中建立了主流流场等效分析模型,通过仿真得到活塞壁面受力大小,再由伯努利方程推导得到液压阻力系数k_1,并以某成熟制退机为例进行了方法验证。按照该方法,研究了后坐速度V和流道截面积a_x对k_1的影响,其在后坐过程中是动态变化的,随着后坐速度、流道面积减小,在一定范围内逐渐增大。在所设计的制退机结构参数条件下,结合后坐阻力仿真与试验结果对比,k_1合理的取值范围为2.4~2.7。

Hydraulic resistance coefficient k_1 reflecting mainstream channel structure＇s characteristic is a key parameter in artillery recoil mechanism design. It can be initialized with tests when channel structures are similar,otherwise it may be different completely. Here,a cylinder wall groove recoil mechanism was studied. For obtaining the reasonable range of k_1 in theoretic design,the influencing parameters were studied. Based on the mainstream channel structure analysis and reasonable simplification,the piston rod was fixed,the recoil velocity of the recoil rod V was simulated with inlet velocity V＇ and the free outlet was set,the equivalent flow field model was built and simulated in Fluent. Under the certain condition of inlet velocity V＇ and the channel cross-section area ax,the piston force was calculated. And then,the coefficient k_1 was deduced with Bernoulli equation. The presented method was validated with a mature recoil mechanism. According to this method,the influences of V and axon k_1 were studied. It was shown that the coefficient k_1 increases within a range gradually with decrease in V and a_x during recoil; under conditions of the recoil mechanism＇s parameters here,and using the comparison between the simulated recoil force and the tested one,the reasonable range of k_1 is 2. 4 ~ 2. 7.