固冲发动机补燃室内强迫对流条件下硼颗粒燃烧速率研究

硼颗粒在通过固体火箭冲压发动机的燃气发生器喷管进入补燃室的过程中,颗粒通常都会受到高速气流的作用。此时,静止条件下硼颗粒的燃烧模型不再适应。对强迫对流条件下的硼颗粒燃烧的二维问题建立了数学模型,通过物理、数学简化,将偏微分方程组化为易于求解的常微分方程组,最后得到燃烧速率的显示表达式,并进行了求解,给出了硼颗粒周围边界层内温度场、浓度场及颗粒燃烧速率随雷诺数Re的变化规律。     

缩比推力室甲烷传热试验研究

为了研究火箭发动机推力室冷却通道内的甲烷传热和流阻特性,研制了缩比推力室甲烷传热试验系统,并以推力室挤压热试验的形式进行了5次超临界甲烷传热试验和2次亚临界甲烷传热试验研究.超临界甲烷传热试验燃烧室压力为5.5～7.5 MPa,燃烧室氢氧混合比约为6.8,甲烷温度为128～230 K,甲烷冷却剂流量为5～7 kg/s,甲烷冷却剂入口压力为8.3～11.7 MPa.亚临界甲烷传热试验的室压约为4 MPa,氢氧混合比2.8,甲烷温度为：128～189 K,甲烷冷却剂流量约为2.9 kg/s,甲烷入口压力为3～3.5 MPa.通过试验研究获得了液态甲烷在推力室冷却通道内超临界压力状态和亚临界压力状态下的传热和流阻特性.     

西飞公司应用振动时效技术的现状及前景分析

通过介绍振动时效的原理、工艺特点及其应用情况，并与热时效进行了对比，进而阐述了振动时效技术的优点及工艺局限性，并就在西飞公司的应用前景进行了分析，指出为提高产品质量和效率，应积极开展振动时效技术的研究。     

自适应直角坐标网格方法在对流换热数值模拟中的应用

复杂几何边界是对流换热计算面临的主要难点之一。自适应直角坐标网格方法可以比较方便的处理复杂几何边界,但其应用目前主要集中于可压无粘流的Euler方程、可压粘性流的Navier-Stokes方程的外部绕流计算。本文应用自适应直角坐标网格方法计算了两个不可压内流对流换热算例,并把计算结果同商用CFD软件STAR-CD的计算结果进行了对比。自适应直角坐标网格方法在本文的两个算例中得到了同STAR-CD一致的结果。这说明采用该方法数值模拟对流换热问题是适用的。      

空气流速和自热效应对湿度传感器测量准确度的影响

通过对多种典型型号湿度传感器在不同空气流速条件下对同一相对湿度测量结果的变化的实验研究,得出了0～1.5 m/s流速范围内湿度传感器的示值随流速的变化趋势,即示值随流速增大而增大,总变化量最大达2%RH以上,且变化主要发生0.5 m/s以下的低流速情况下,同时传感器表面温度随流速增大而降低,两者变化趋势相互吻合。进一步分析表明,上述现象是湿度传感器的自热效应和空气与传感器之间的对流换热效应共同作用的结果,它给湿度传感器的测量结果带来新增不确定度。     

Study of thermo-fluidic characteristics for geometric-anisotropy Kagome truss-cored lattice

The aim of this paper is to provide a comprehensive comparison of the thermal insulation and heat transfer performance for Kagome truss-cored lattice along two perpendicular orientations OA and OB. Three test conditions are conducted under forced air convection for the titanium sandwich panel fabricated by 3 D printing technology. The thermo-fluidic characteristics are further explored by numerical simulation to reveal the underlying mechanisms of heat transfer enhancement.The results indicate that the orientation OB exhibits better thermal insulation than orientation OA under the identical temperature loading, while the latter outperforms the former by up to 20% higher overall heat transfer performance. In particular, the endwalls and lattice core in orientation OA achieve 9.7% and 22.5% higher area-averaged Nusselt number respectively than that in orientation OB for a given Reynolds number. The heat transfer superiority of orientation OA comes from the unique topology which induces the large scale spiral primary flows, facilitating the heat exchange between the cooling air and the surfaces of sandwich panel. However, the complex flow mixing leads to a maximum of 20% higher friction factor in orientation OA than that in orientation OB.     

竖直平板间湍流自然对流中螺旋羽流结构的实验研究

应用粒子图像测速技术（PIV）对竖直平板间水的温差湍流自然对流的流场进行了测量,并由测量所获得的速度场获取了涡量分布和散度分布。测量结果表明,在流场中的竖直展向截面和水平流向截面上都存在大尺度涡流结构,而且在部分涡量集中区域同时具有正的或者负的散度集中,速度矢量分布也表明水平截面上的这部分涡流结构呈现着清晰的源或汇的特征。这些现象都表明这部分旋转着的流体不但有切向速度,还有径向速度。这意味着这部分流体在旋转的同时也有向上或向下的运动,即同时具有在同方向上的涡量和速度,即螺度,而这是螺旋羽流结构的特征。这些涡结构,尤其是水平流向截面上具有径向速度的涡流结构的存在证实了竖直平板之间的湍流自然对流流场中大尺度的螺旋羽流结构的存在。     

Numerical optimization of transonic natural laminar flow nacelles

Natural laminar flow nacelle is a promising technology for drag reduction. In this paper,an optimization platform is established for the design of transonic axisymmetric and threedimensional natural laminar flow nacelles for large civil aircraft. The platform adopts the class/shape transformation method for geometric parameterization, a four-equation transition model for transition prediction, and the differential evolution algorithm combined with the radial basis function surrogate model as the...     

A linear stability analysis of large-Prandtl-number thermocapillary liquid bridges

A linear stability analysis is applied to determine the onset of oscillatory thermocapillary convection in cylindrical liquid bridges of large Prandtl numbers (4  Pr  50). We focus on the relationships between the critical Reynolds number Re_c, the azimuthal wave number m, the aspect ratio Γ and the Prandtl number Pr. A detailed Re_c–Pr stability diagram is given for liquid bridges with various Γ. In the region of Pr > 1, which has been less studied previously and where Re_c has been usually believed to decrease with the increase of Pr, we found Re_c exhibits an early increase for liquid bridges with Γ around one. From the computed surface temperature gradient, it is concluded that the boundary layers developed at both solid ends of liquid bridges strengthen the stability of basic axisymmetric thermocapillary convection at large Prandtl number, and that the stability property of the basic flow is determined by the “effective” part of liquid bridge.     

振动表面自然对流强化换热特性

基于振动影响流动换热边界层发展的思路,通过实验方法对振动条件下的自然对流换热特性进行研究.实验采用电铃谐振器作为加热膜的激振源,并利用红外测温技术对表面温度场进行了测量.结果表明:振动对自然对流的强化可提高90.7%.在等热流密度条件下,振动能量越大,换热越好;在等振动能量条件下,热流密度越小,换热越强.研究结果为强化表面自然对流换热提供了一种新思路.