Abstract
Addressing the issue of sealing failure in liquid hydrogen triple-offset butterfly valves within rocket fuel delivery systems under ultra-low temperature conditions due to insufficient cold shrinkage compensation capability, this paper first proposes a soft-sealing elastic compensation structure. Its sealing performance is evaluated using a thermo-mechanical coupling method. Secondly, sensitivity analysis using the Spearman method identifies key optimization variables: radial offset distance D(e), third offset angle α, sealing surface width B, and sealing surface interference T. The optimization objectives are the maximum contact stress P(1max) and average contact stress P(1ave) during forward sealing, and the maximum contact stress P(2max) and average contact stress P(2ave) during reverse sealing. Finally, an optimal Latin hypercube sampling method is used to construct the sample space, and a high-precision RBF surrogate model combined with the NSGA-II algorithm is employed to find excellent Pareto front solutions. After optimization, the Maximum contact stress of the butterfly valve sealing structure during forward sealing decreased by 23.43%, and the average contact stress decreased by 22.41%; during reverse sealing, the Maximum contact stress increased by 51.07%, and the average contact stress increased by 48.83%. The optimized butterfly valve sealing structure achieves reliable bidirectional sealing under liquid hydrogen ultra-low temperature conditions.