火箭推进

典型低温推进剂的热力学性能参数评估

刘柏文^1,2,徐元元¹,雷刚¹,厉彦忠^1,2

(1.航天低温推进剂技术国家重点实验室,北京100028;2.西安交通大学能源与动力工程学院,陕西西安710049)

Evaluation of thermodynamic performance parameters for typical cryogenic propellant

LIU Bowen^1,2, XU Yuanyuan¹, LEI Gang¹, LI Yanzhong^1,2

(1.State Key Laboratory of Technologies in Space Cryogenic Propellants, Beijing 100028, China; 2.School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an 710049, China)

Keywords：cryogenic propellants; flow resistance; storage characteristics; densification

备注

摘要

全文

图/表

参考文献

近年来,低温推进剂在火箭推进领域得到了广泛应用,针对液氧、液氢以及液甲烷等低温推进剂的研究也得到了深入开展。然而,有关低温推进剂热力学性能的研究虽有开展,但各种推进剂性能的特点和差异缺乏研究,对低温推进剂的热力学性能缺乏综合性分析研究和系统认识。统计了1960年以来火箭推进剂的使用以及按照火箭级应用分布情况,对低温推进剂在火箭推进领域的应用与发展进行系统性综述。从低温推进剂的基础热物理性质出发,面向航天推进应用,对不同低温推进剂的动力特性、传输特性、贮存特性以及致密化特性4个方面进行综合评估。结果表明:液氢推力特性最好,氢氧发动机理论比冲可达457 s。相同管路和工况条件下,液氢流动阻力最小,液氧流动温升最小,液甲烷流动阻力和温升特性表现居中。以管长为10 m、管内径为0.1 m的加注管路为例,液氢流动压降小于5 kPa,液氧流动温升小于0.5 K。在地面停放过程中液氧和液甲烷温升小,贮箱增压慢,同时液甲烷热分层现象较弱。对于高5 m、直径3 m的圆柱形贮箱来说,当外界热流密度为50 W/m2时,液氢温升可达4.83 K,液氧仅为1.93 K; 液氧贮存周期可达 36.5 h,液氢仅为5.5 h。而液甲烷发生热分层所需的临界热流最大,为14 W/m2,相对而言液甲烷贮存性能最佳。采用过冷致密化技术能够改变推进剂应用性能,对其动力、传输和贮存特性会产生显著影响,当贮箱体积维持不变,采用深度过冷技术(液氢和液甲烷达三相点温度)可使液氢/液氧、液甲烷/液氧燃料的相对载荷能力分别提升8.66和6.89; 液氧、液甲烷和液氢的无气化贮存周期分别延长达322.82、354.67和285.45,但黏度增加会使得流动阻力增加41.36、15.42和18.64。总体看来,对推进剂过冷致密化处理后,其动力特性和贮存特性明显提升,传输特性有所降低。

In recent years, cryogenic propellants have been widely used in the field of rocket propulsion, and the research on cryogenic propellants such as liquid oxygen, liquid hydrogen and liquid methane has also been carried out in depth.However, although the research on the thermodynamic properties of cryogenic propellants has been carried out, the characteristics and differences of various propellants have not been studied.In addition, the thermodynamic properties of cryogenic propellants have not been comprehensively analyzed and systematically understood.In this paper, the application and development of cryogenic propellant in the field of rocket propulsion are systematically reviewed based on the statistics of the used rocket propellants since 1960s and the distribution of rocket stage application.Based on the basic thermophysical properties of cryogenic propellants, the dynamic characteristics, transport characteristics, storage characteristics and densification characteristics of different cryogenic propellants were comprehensively evaluated for aerospace propulsion applications.The results show that the liquid hydrogen has the best thrust characteristics, and the theoretical specific impulse of hydrogen-oxygen engine can reach 457 s.Under the same pipeline and working conditions, the liquid hydrogen has the smallest flow resistance, the liquid oxygen has the smallest flow temperature rise, and the overall performance of the liquid methane transmission characteristics is in the middle.Taking the filling pipe with a length of 10 m and an inner diameter of 0.1 m as an example, the liquid hydrogen flow pressure drop is less than 5 kPa, and the liquid oxygen flow temperature rise is less than 0.5 K.In the process of ground parking, the temperature rise of liquid oxygen and liquid methane is small, the tank pressurization is slow, and the thermal stratification of liquid methane is weak.For a cylindrical tank with a height of 5 m and a diameter of 3 m, the temperature rise of liquid hydrogen is 4.83 K and that of liquid oxygen is only 1.93 K when the heat flux is 50 W/m2.The storage period of liquid oxygen is 36.5 h, and that of liquid hydrogen is 5.5 h.The critical heat flow required for thermal stratification of liquid methane is 14 W/m2, and the storage performance of liquid methane is the best.The supercooling densification technology can change the propellant application performance, which will have a significant impact on the power, transport and storage characteristics.When the tank volume remains unchanged, the adoption of deep supercooling technology(triple point temperature)of liquid hydrogen and liquid methane can increase relative load capacity of liquid hydrogen/oxygen and liquid methane/oxygen fuel by 8.66 and 6.89.The non-gasification storage periods of liquid oxygen, liquid methane and liquid hydrogen are extended to 322.82, 354.67 and 285.45, respectively, but the flow resistance increased by 41.36, 15.42 and 18.64 due to the increase of viscosity.In general, after the subcooling and densification of propellant, its dynamic characteristics and storage characteristics are obviously improved, while its transmission characteristics are reduced.

引言
1 低温推进剂使用情况
2 低温推进剂重要热物性及指标
3 结论

表1 不同年代推进剂使用情况<br/>Tab.1 Data of propellant usage in different ages

表1 不同年代推进剂使用情况
Tab.1 Data of propellant usage in different ages

图1 不同年代推进剂使用情况<br/>Fig.1 Propellant usage in different ages

图1 不同年代推进剂使用情况
Fig.1 Propellant usage in different ages

图2 推进剂在火箭不同级上的使用情况<br/>Fig.2 Propellant usage at different stages of the rocket

图2 推进剂在火箭不同级上的使用情况
Fig.2 Propellant usage at different stages of the rocket

表2 3种典型低温推进剂的常规热物性数据(标准沸点状态)<br/>Tab.2 Conventional thermal properties data of three typical cryogenic propellants(at normal boiling point states)

表2 3种典型低温推进剂的常规热物性数据(标准沸点状态)
Tab.2 Conventional thermal properties data of three typical cryogenic propellants(at normal boiling point states)

表3 推进剂推力特性参数<br/>Tab.3 Thrust characteristic parameters for different propellants

表3 推进剂推力特性参数
Tab.3 Thrust characteristic parameters for different propellants

图3 不同型号火箭的比冲与密度分布情况<br/>Fig.3 Specific impulse and density distribution of different types of rockets

图3 不同型号火箭的比冲与密度分布情况
Fig.3 Specific impulse and density distribution of different types of rockets

图4 低温推进剂的流动压降随流速的变化曲线<br/>Fig.4 Flow pressure drop curve of cryogenic propellant varies with flow velocity

图4 低温推进剂的流动压降随流速的变化曲线
Fig.4 Flow pressure drop curve of cryogenic propellant varies with flow velocity

图5 低温推进剂管道流动温升随流速的变化曲线<br/>Fig.5 Curve of flow temperature rise with flow velocity in cryogenic propellant pipeline

图5 低温推进剂管道流动温升随流速的变化曲线
Fig.5 Curve of flow temperature rise with flow velocity in cryogenic propellant pipeline

图6 贮箱内低温推进剂温度随时间变化(热流密度50 W/m2,贮箱高5 m,直径3 m)<br/>Fig.6 Temperature of low-temperature propellant in the tank varies with time(heat flux of 50 W/m2, height of 5 m, diameter of 3 m)

图6 贮箱内低温推进剂温度随时间变化(热流密度50 W/m2,贮箱高5 m,直径3 m)
Fig.6 Temperature of low-temperature propellant in the tank varies with time(heat flux of 50 W/m2, height of 5 m, diameter of 3 m)

图7 贮箱内压力随时间变化规律(热流密度50 W/m2,贮箱高5 m,直径3 m)<br/>Fig.7 Pressure in storage box varies with time(heat flux of 50 W/m2, height of 5 m, diameter of 3 m)

图7 贮箱内压力随时间变化规律(热流密度50 W/m2,贮箱高5 m,直径3 m)
Fig.7 Pressure in storage box varies with time(heat flux of 50 W/m2, height of 5 m, diameter of 3 m)

表4 修正瑞利数与热分层的关系<br/>Tab.4 Relationship between the revised Rayleigh number and thermal stratification

表4 修正瑞利数与热分层的关系
Tab.4 Relationship between the revised Rayleigh number and thermal stratification

图8 低温推进剂的瑞利数随热流变化曲线(特征尺寸为2.5 m,标准沸点状态)<br/>Fig.8 Rayleigh number curve with heat flow of cryogenic propellant at normal boiling point states with characteristic size of 2.5 m

图8 低温推进剂的瑞利数随热流变化曲线(特征尺寸为2.5 m,标准沸点状态)
Fig.8 Rayleigh number curve with heat flow of cryogenic propellant at normal boiling point states with characteristic size of 2.5 m

表5 过冷低温推进剂热物理性质<br/>Tab.5 Thermophysical properties of subcooled cryogenic propellants

表5 过冷低温推进剂热物理性质
Tab.5 Thermophysical properties of subcooled cryogenic propellants

图9 低温推进剂组合密度比冲随温度变化曲线[当量温度T*=(T-TTP)/(TNBP-TTP)]<br/>Fig.9 Density specific impulse curve with temperature for low-temperature propellant combination [equivalent temperature T*=(T- T TP)/( T NBP- T TP)]

图9 低温推进剂组合密度比冲随温度变化曲线[当量温度T*=(T-TTP)/(TNBP-TTP)]
Fig.9 Density specific impulse curve with temperature for low-temperature propellant combination [equivalent temperature T*=(T- T TP)/( T NBP- T TP)]