表面热流辨识技术在边界层转捩位置测量中的应用初步研究

目前工程飞行试验中主要采用近壁热电偶测温法来确定飞行器表面流动的边界层转捩位置,由于测点离表面较近,对温度传感器量程和结构强度有较高要求。为此,提出了基于表面热流辨识技术确定转捩位置的基本思想和处理方法,测点可以距离表面相对较远。但是,当测点越远离受热面,辨识问题的不适定性会越强,因此需要采用仿真辨识方法来对传感器安装位置进行合理选取。在给出二维传热模型表面热流辨识算法的基础上,对两个算例进行了仿真辨识分析。结果表明：基于表面热流辨识技术确定转捩位置是可行的,能给出较为准确的转捩区域判断。     

复合材料质量烧蚀率计算模型实验研究

通过对CF/S- 157PF复合材料进行氧-乙炔烧蚀试验研究,得到了质量烧蚀率,并利用多元线性回归方法,拟合得到了该参数与热流密度和烧蚀时间的数学模型,即M=0.043.q0.128·t-0.191.经检验,该回归模型适用性较好,预测精度较高,为复合材料该项烧蚀性能的评估建立了快速、有效、可靠的试验方法.     

M3条件下乙烯燃料超燃冲压发动机空气节流点火试验

在隔离段入口Ma=3(模拟飞行马赫数6.5)条件下,采用乙烯燃料的超燃冲压发动机点火十分困难。为解决该难题,采用了空气节流作为辅助点火措施。基于脉冲燃烧风洞直连式试验平台进行了空气节流点火试验,通过壁面压力测量,获得了节流点火的火焰发展历程。以点火时间为指标,对节流流量、乙烯当量比、节流时间等参数进行了定量分析,节流流量的调节范围为0%~45%,乙烯当量比调节范围为0.6~1.2,节流时间调节范围为190~350ms。分析了三个节流参数各自的作用机理,通过数据拟合,绘制了节流流量与点火时间、乙烯当量比与点火时间的关系曲线,揭示了节流时间与点火时间的关系。      

Validation of a novel mixing-plane method for multistage turbomachinery steady flow analysis

The steady calculation based on the mixing-plane method is still the most widely-used three-dimensional flow analysis tool for multistage turbomachines. For modern turbomachines, the trend of design is to reach higher aerodynamic loading but with still further compact size. In such a case, the traditional mixing-plane method has to be revised to give a more physically mean-ingful prediction. In this paper, a novel mixing-plane method was proposed, and three representa-tive test cases including a transonic compressor, a highly-loaded centrifugal compressor and a high-pressure axial turbine were performed for validation purpose. This novel mixing-plane method can satisfy the flux conservation perfectly. Reverse flow across the mixing-plane interface can be resolved naturally, thus making this method numerically robust. Artificial reflection at the mixing-plane interface is almost eliminated, and then its detrimental impact on the flow field is min-imized. Generally, this mixing-plane method is suitable to simulate steady flows in highly-loaded multistage turbomachines.     

热流响应时间测试方法研究

论述了热流传感器响应时间测试在航空、航天、能源及国民经济各领域中的作用和意义,介绍了热流响应时间测试技术研究情况,描述了研制的热流响应时间测试装置及应用情况。实验证明,所设计的测试装置可以实现预期目标,并对热流传感器的响应时间进行测试。     

空间遥感器的热／结构／光学分析研究

作为一个空间遥感器整机热光学（热／结构／光学）集成分析过程，对空间遥感器主要光机结构简化，进行导热特性分析和等效热阻计算；利用软件计算在轨道上典型工况的空间外流热和内热源分布；建立有限元温度场分析模型和结构热弹性分析模型，计算全机稳、瞬态温度场分布，均匀温度和特定温度场下的位移场，得到各光学元件的位移；利用光学分析程度计算的公差计算结果插值计算遥感器光学系统由于光学元件的热致刚体位移（离轴、轴向位移和倾斜）而产生的光学性能变化。     

振弦式陀螺电磁驱动结构设计与电磁分析

依据振弦式陀螺的工作原理提出一种振弦式陀螺电磁驱动方案,分析了振弦式陀螺电磁驱动电学模型与动力学模型,初步设计了振弦式陀螺电磁驱动结构,运用MATLAB数值软件设定目标参数和初始值计算得到初始结构尺寸;应用Maxwell电磁软件分析了振弦式陀螺电磁驱动系统中永磁体尺寸、永磁体间距、背磁片、Halbach永磁体阵列等因素对电磁驱动模型气隙磁感应强度的影响;最后优化了振弦式陀螺结构模型并进行了电磁驱动结构模型仿真分析。结果表明,电磁驱动整体结构模型气隙磁感应强度得到很大提升,可以很好地降低陀螺功耗,提高陀螺框架驱动力,优化陀螺结构尺寸,从而验证了振弦式陀螺电磁驱动方案模型的可行性,为振弦式陀螺的结构优化设计与实际产品试制研究奠定了理论基础。     

表面涂漆对火箭尾翼热结构的影响

建立了运载火箭的气动加热工程计算方法,计算区域横跨连续流、稀薄过渡流和自由分子流,包括层流、转捩和湍流等各流态。重点研究了尾翼与芯级间的干扰加热,数值求解了自然正交曲线坐标系下尾翼内部二维单层和双层材料热传导方程,给出了典型部位的内外表面温度计算结果,表明表面涂漆对尾翼前缘并不能起到防热隔热效果。     

Uncertainties in gravity wave parameters,momentum fluxes,and flux divergences estimated from multi-layer measurements of mesospheric nightglow layers

Measurements of dynamic parameters of atmospheric gravity waves, mainly the vertical wavelength, the momentum flux and the momentum flux divergence, are affected by large uncertainties crudely documented in the scientific literature. By using methods of error analysis, we have quantified these uncertainties for frequently observed temporal and spatial wave scales. The results show uncertainties of ～10%, ～35%, and ～65%, at least, in the vertical wavelength, momentum flux, and flux divergence, respectively. The large uncertainties in the momentum flux and flux divergence are dominated by uncertainties in the Brunt-Väisälä frequency and in spatial separation of the nightglow layers, respectively. The measured uncertainties in fundamental wave parameters such as the wave amplitude, intrinsic period, horizontal wavelength, and wave orientation are ～10% or less and estimated directly from our nightglow image data set. Other key environmental quantities such as the scale height and the Brunt-Väisälä frequency, frequently considered as constants in gravity wave parameter estimations schemes, are actually quite variable, presenting uncertainties of ～4% and ～9%, respectively, according to the several solar activity and seasonal atmosphere scenarios from the NRLMSISE-00 model simulated here.     

Old tail lobes effect on the solar-wind – Magnetosphere energy transport for the 27 August 2001 substorm

The magnetic flux of tail lobes Ψ is divided in two parts of comparable values Ψ₁ and Ψ₀₂, with the first that appears during substorm and the second, observed before substorm start. The first was named “new magnetic flux”, the second – “old magnetic flux”. The first, Ψ₁, is known to play a definitive role in the energy transport from the solar wind into the magnetosphere-ionosphere-atmosphere system, but the role of Ψ₀₂ in this transport is not well known. From the 27 August 2001 substorm data we study the involvement in the above transport process of the old flux Ψ₀₂. This involvement is observed in the polar cap (PC) area, which existed prior to the substorm and is called respectively “the old PC”. In this study, as distinct from earlier works, we use the balance equation of the energy stored in magnetosphere and energy consumed. Activation of the old PC magnetic flux Ψ₀₂ was found to increase the energy input by ∼85% in the event under consideration.