This work presents a novel approach for the modeling of the entrainment in the numerical simulation of the internal ballistics of hybrid rocket engines with paraffin-based fuels. This model, coupled with a more sophisticated gas–surface interaction treatment, is an improvement of the model previously developed by some of the authors, which was based on some oversimplifying assumptions. Indeed, the old entrainment model was performed in a close range of averaged oxidizer mass flux, and it made the overall numerical model not scalable on different motor sizes. Therefore, a new correlation is introduced, which is based on the Reynolds number and takes into account the dependence of the entrained fraction on the shear stress exerted by the gas flow and the tube diameter. Firstly, the new and the old numerical models are compared in order to highlight the improvement obtained by the current efforts. Then, the model has been validated on experimental tests involving two different thrust class motors. Finally, the effect of the motor size on the fuel consumption is shown, thus revealing the crucial influence of the recirculating zone extension due to the oxidizer axial injection.

这项工作提出了一种新的方法，用于在混合火箭发动机的内部弹道数值模拟中对基于石蜡的燃料的夹带进行建模。该模型与更复杂的气体-表面相互作用处理相结合，是一些作者先前基于一些过于简单化的假设开发的模型的改进。事实上，旧的夹带模型是在平均氧化剂质量通量的近距离范围内进行的，它使整体数值模型无法在不同的电机尺寸上扩展。因此，引入了一种新的相关性，它基于雷诺数，并考虑了夹带分数对气流和管径施加的剪切应力的依赖性。首先，新旧数值模型进行了比较，以突出当前努力取得的改进。然后，该模型已在涉及两个不同推力级电机的实验测试中得到验证。最后，显示了电机尺寸对燃料消耗的影响，从而揭示了由于氧化剂轴向喷射而导致的再循环区扩展的关键影响。