火星探测天线组阵数据接收技术研究和验证实验

为了满足我国首次火星探测任务的需要，确保探测器有效载荷科学数据的顺利下传，将采用天线组阵的方式进行数据接收。天线组阵数据接收技术在航天工程中的应用国内尚属首次，为此开展了信号合成方法和处理流程的研究，提出了利用模型计算和基于科斯塔斯环的搜索估计相结合的初始时延和多普勒频差快速估计方法。利用现有的密云站50 m天线和昆明站40 m天线，以嫦娥3号着陆器数传信号为实验对象，开展了天线组阵与数据接收技术检验实验。研究和实验结果表明，全频谱合成方法优于符号流合成方法，其合成损耗小于等于 0.45 dB ，可用于我国首次火星探测任务天线组阵的信号合成；初始时延和多普勒频差快速估计方法可提高广域组阵信号互相关的搜索效率；所确定的信号合成技术流程和数据处理方法可用于后续信号合成软硬件设备的研制和开发。     

Influence of Interference Effects of the Rotor on the Launch Dynamics of Gliding Unmanned Aerial Vehicle

A mathematical model of the gliding unmanned aerial vehicle (UAV) motion is performed taking into account the interference effect of the main rotor on the UAV. Calculated values are presented for the interference addition to the aerodynamic coefficients of forces and moments on the UAV path section close to the carrier. The problems of stabilization and control are solved, providing stability of the UAV motion at the launch with due account of the aerodynamic interference and the effect of short-term upper stage engine operation, as well as a safe distance between the carrier and the UAV during their simultaneous motion.     

Influence of thermal protection on the temperature state of the screen and casing

This work is devoted to the experimental study of the method of thermal protection of the environment by shielding from the hot body of the high-temperature gas turbine engine on a model setup under conditions of free convection (bulk screen), and with the injection of air through a porous screen. The generalized dependences of thermal protection are obtained that permit the temperature of the screen and the casing under free convection and injection of air through a porous screen to be predicted.     

A combined method for calculating the trajectories of suspended particles

A combined method for calculating the trajectories of suspended particles in the hydrodynamic velocity fields is proposed. The method utilizes capabilities of existing CFD codes and parallel computing on a computer with a graphics card that supports CUDA technology. The software package that implements the method is described.     

Simulation of thermal radiation emitted by heterogeneous combustion products in the combustion chamber of a model engine

The paper presents technology and results of the computational experiment on investigation of thermal radiation in the combustion chamber of a model rocket engine. Dependence of optical properties, radiation characteristics and emission characteristics on the main determining factors and parameters is analyzed.     

基于拟合的吸收光谱反演算法研究*

可调谐半导体吸收光谱技术作为一种先进的光谱检测手段,已广泛应用于大气环境监测、工业过程控制等领域,实现不同领域组分浓度、温度、压力等参数的高精度探测。技术分为直接吸收光谱技术和波长调制光谱技术,通过选取不同的目标函数,验证拟合算法在吸收光谱技术中的可行性,两种技术均可通过构建合适的目标函数结合拟合算法实现吸收信息的精确反演,依据物理过程建立吸收模型,分别将直接吸收技术的光强、吸光度及透过率和波长调制光谱技术的光强及谐波信号作为拟合对象,实现了拟合参数的精确计算,从理论上验证了处理方法的准确性,扩展了拟合算法在检测仪器开发方面的应用,为各领域的发展提供了技术保障。     

Simulation of flow and mixture formation nonstationarity in combustion chambers

In this paper, attention was focused on the matter of simulating a flow, the mixture and vapor formation in the GTE combustion chamber without regard for combustion. The software developed by the authors was used for simulation. For comparison and analysis, also presented are the simulation results obtained in Fluent software. The characteristic features of a flow and the distribution of vaporous and droplet-liquid fuel throughout the flame tube model volume are revealed.     

Dynamics of a cylindrical shell with a locally damaged protective coating

An approximate solution of a problem on the dynamic behavior of a thin elastic circular cylindrical shell with the damaged heat-protective layer section is presented. The influence of the fracture zone size and its mass on the frequencies of shell natural vibrations and its dynamic deflections is analyzed.     

Analysis of stress state in a root-airfoil transition zone of hollow wide chord fan blades

In this paper, under consideration is the complex approach to analyzing the operation of a simulator for the hollow blade made from the VT6 titanium alloy. The stress state parameters in the hollow-monolithic part transition zone of the cantilevered simulator at bending under the distributed load are determined.