摘要
吸气式核热推进发动机作为吸气式火箭领域的先进应用之一,其高热流密度下堆芯热力行为与冷却剂特性存在强耦合关系,堵流则为该类反应堆独特且关键的事故现象之一。本研究基于一维流体与三维固体热力耦合形式,结合点堆动力学方程,对典型的吸气式核热推进反应堆堵流事故下的瞬态响应进行了核-热-力多场耦合模拟。结果表明,本研究所提出的耦合求解形式可以快速准确计算包括多种反馈机制在内的反应堆瞬态响应过程,主要温压偏差不超过3%,推力计算偏差不超过5%;随着堵流面积的增加,堵流限制因素从温度向堆后总压转变;可容许的堵流因子随着堵流占比的增加与堵流位置的提升逐步降低并趋向于全局堵流状态;采用最低堵流初始堆后总压1.53MPa作为堵流失稳的预警条件具有保守性及一致性。
[Background]With the further improvement of engine thrust,specific impulse,and inherent load requirements in modern aerospace systems,nuclear thermal propulsion(NTP)technology has considerable development potential.Air-breathing nuclear thermal propulsion engines do not need to carry oxidants and chemical fuels,directly drawing air from the atmosphere,heating,and generating thrust,further reducing the inherent load of the engine.[Purpose]This study aims to explore the response of air-breathing NTP reactors to flow-blockage accidents,and study the influence of blockage factors on the stability of reactor operation under different blockage ratios and positions to obtain the pre-judgment parameters.[Methods]First of all,a cross dimensional neutronics-thermal hydraulics-mechanicals multi-physics field coupling model was established with zero-dimensional point reactor kinetics equations,one-dimensional fluid,and three-dimensional solid thermo-mechanical forms.Then,multiple verification and validation(V&V)tests were conducted to verify the correctness of the code for efficiently calculating the transient response of the system,including multiple feedback mechanisms,with a deviation of less than 5%.Finally,the response of reactor flow-blockage accidents at different degrees and positions at a blockage area rate of 0 to 100%under rated operating conditions was investigated.[Results]The calculation results indicate that as the proportion of blockage areas increases,the limiting factor for core safety and stability shifts from temperature to blockage thrust loss,and the maximum blockage factor allowed for the engine to achieve self-stabilization generally decreases to 0.74.In large-scale blockage accidents,temperature and stress are maintained within safe levels.When the blockage factor exceeds the limit,the low total pressure behind the reactor rapidly decreases the thrust and forms positive feedback,causing engine instability.As the blockage position moves downstream,the reactor is more likely to enter an unstable state under the same blockage factor conditions.When the initial total pressure behind the reactor after blockage is less than 1.53 MPa,it can be considered that the current blockage factor of the reactor is only 15.3%at most different from the critical instability value.After organizing a large amount of data,the total pressure of 1.53 MPa behind the reactor can be considered as a pre-judgment condition for approaching instability.The value may vary under different reactor conditions,but the parameter has system conservation and consistency.Taking the allowable temperature limit and the initial total pressure behind the reactor into account,it can provide early warning for any uncontrolled flow conditions.[Conclusions]Simulation results of this study provide experience for early warning and intervention of flow-blockage accidents in air-breathing nuclear thermal propulsion engine working.
作者
段子勉
李彬乾
章静
苏光辉
巫英伟
贺亚男
王明军
郭凯伦
DUAN Zimian;LI Binqian;ZHANG Jing;SU Guanghui;WU Yingwei;HE Yanan;WANG Mingjun;GUO Kailun(Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology,School of Nuclear Science and Technology,Xi'an Jiaotong University,Xi'an 710049,China)
出处
《核技术》
北大核心
2025年第5期196-212,共17页
Nuclear Techniques
基金
中核集团青年英才项目资助。
关键词
吸气式核热推进
堵流
核-热-力多场耦合
失稳
Air-breathing nuclear thermal propulsion
Flow-blockage
Neutronics-thermal hydraulics-mechanicals multi-physics field coupling
Instability
