高亚声速大弯角轴流压气机平面叶栅损失模型研究

基于亚声速叶栅设计点损失预估模型,结合无粘S1流场与附面层迭代计算发展了一套计算大弯角轴流压气机平面叶栅流场程序。增加弯度比分布及最大厚度修正得到设计点损失预估模型,采用马赫数修正后的叶栅有效工作范围得到一套大弯角叶栅全工况损失预估模型。分析了轴向密流比在实验中对叶栅损失系数的影响。结果表明,S1流场计算程序与修正后的损失预估模型均能准确地预估出大弯角叶栅设计点损失系数,误差分别小于0.006与0.004。非设计点损失模型能有效地预估得到叶栅有效工作范围内的损失随攻角的分布。初步验证了损失模型对高亚声速大弯角平面叶栅损失系数预估的准确性。     

Antenna systems of radio equipment for advanced UAVs: Problems and lines of development

The paper deals with the problem of creating airborne antenna systems for advanced unmanned aerial vehicles (UAVs). The ways of solving the basic problems, based on a combination of empirical approaches, electrodynamic simulation, and experimental results are proposed.     

Experimental study of pressure fields in a multilobe journal bearing

An experimental pressure field in operating clearance and flowrate parameters analysis for different eccentricities, inlet oil pressures, and journal rotating velocities are presented for a radial multilobe journal bearing. Lubricating film breakdown zones in bearing oil ducts caused by complicated construction and journal rotation are observed.     

航天器用薄膜温度传感器的研制及性能研究

飞行器以高超声速飞行时瞬间温升可达1 600℃以上,为了保证飞行器的可靠和运行安全,准确实时测量热防护系统表面温度显得尤为重要。针对高温环境实时测温的技术难题,结合磁控溅射技术和陶瓷烧结技术,提出了一种引线和传感器基底一体化的微小型高温薄膜温度传感器结构。采用高温检定炉对传感器陶瓷基底的高温绝缘性进行了测试,并使用多种微观形貌表征方法对传感器主要结构材料进行筛选,得到薄膜温度传感器制备所需的最佳材料组合。进行了薄膜温度传感器静态标定和综合性能高温考核试验,结果表明,所研制传感器灵敏度、重复性的变化与标准热电偶基本保持一致,在实际环境温度低于1 500℃时,传感器测量误差不超过4‰,可在1 200℃高温环境中连续准确测温6 h以上,且测温上限高达1 800℃,验证了该传感器在高温环境中进行测温的可行性和实用性,为航天器表面温度测量和热防护系统优化提供科学依据。     

Experimental study of strain for plates discretely connected to a cylindrical shell

We present the results of an experimental study of deflections for the loaded plates that are discretely connected to a circular cylindrical shell along the generatrix lines. The influence of structure element connection elasticity on these deflections has been examined. The unique experimental setup and three specimens being tested are described. Satisfactory agreement is shown between the experimental results and the calculation data obtained by the simplified mechanical model of a plane problem.     

Control of spacecraft turns in scheduled time using rocket engines

We obtained an on-off control law for two spacecraft (SC) rocket engines creating the angular acceleration in the opposite directions considering that SC is controlled by the rocket engines with an exponential increase of thrust at starting and decrease at shutdown. This control law provides the change-over of SC from the initial angular position to the final one in the scheduled time. A special trajectory consisting of eight typical segments is proposed to identify the angular acceleration and delay of its formation in the rocket engines. Both problems are solved by the method of analytical construction of composite trajectories for the angular turn from the typical segments on which the differential equations of angular motion have analytical solutions. The results are applicable for the development of promising space interceptors and design of onboard control systems.     

Divergence of a plate discretely supported by the stringer system

An approximate solution of the divergence problem, that is, of the static instability of a plate discretely supported by a system of stiffening ribs (stringers) in the gas flow. The critical velocity of divergence is determined in one-term approximation and the influence of stringers on it is analyzed.     

Construction of an airfoil with an irregularity in the flow

Using the method of quasisolutions for inverse boundary-value problems of aerohydrodynamics, a problem of constructing an airfoil was solved by the specified velocity distribution along the sought airfoil contour when there is an irregularity in the flow such as a vorticity source. The cases of a source (sink) and vortex are obtained as particular ones. The airfoils are constructed numerically and analytically and conclusions are made about an influence of the irregularity position and type on the shape and aerodynamic characteristics of the airfoil.     

Analysis of chaotic vibrations for the distributed systems in the form of the Bernoulli-Euler beams using the wavelet transform

A problem on chaotic vibrations of the Bernoulli-Euler beams is formulated. The wavelet transform was first applied to investigate the complex beam vibrations. The validity of results was provided by using two methods of solution, namely, the finite element method and finite difference method.