Experimental investigation on static/dynamic characteristics of a fast-response pressure sensitive paint

An optical-based technique using Pressure-Sensitive Paint(PSP) is a promising method to measure the distribution of surface pressure on an aerodynamic model. The static and dynamic characteristics of a fast-response PSP that is developed in the Chinese Academy of Sciences(CAS)are analyzed and tested to serve as the basis for experiments on unsteady surface measurement using a fast-response PSP. Two calibration systems used for this study are set up to investigate the temperature dependency, response time, and resolution. A data processing method, used for dynamic data, is analyzed and selected carefully to determine the optimum signal. Results show that the fastresponse PSP can be used normally at temperatures from 25 ℃ to 80 ℃. The effect of temperature on the accuracy of the measurement must be considered when temperatures are beyond the temperature range of 30–40 ℃. The dynamic calibration device with a solenoid valve can achieve a pressure jump within a millisecond order. The resolution is determined by the signal-to-noise ratio of the photo-multiplier tube. Results of the measurement show that the response time of the PSP decreases with a large pressure variation, and the response time is below 0.016 s when the pressure variation is under 40 kPa.     

复合涂层刀具钻削高温合金Inconel 718钻削性能研究

高温合金Inconel 718是一种典型的难加工材料,本文利用DEFORM-3D软件对无涂层、TiC单涂层和TiC/Al₂O₃复合涂层硬质合金刀具进行钻削高温合金Inconel 718的仿真分析,研究在不同钻削条件下复合涂层刀具的切削性能,并进行钻削实验进行验证。结果表明：TiC/Al₂O₃复合涂层刀具能有效降低钻削轴向力和钻削温度,其轴向力降低幅度最高为20%,钻削温度最高降低了35%。通过钻削实验验证了仿真模型的准确性,可为实际钻削加工高温镍基合金Inconel 718中选择涂层种类及钻削参数提供参考。     

静基座捷联惯性组合加速度计高阶误差项显著性分析

在标定捷联惯组加速度计时,一般采用多位置试验,但是目前并未对多位置试验所能标定出的误差系数数量和标定结果的有效性进行分析,本文针对这一问题展开了研究.首先,阐述了带有高次误差项的捷联惯组加速度计误差模型.然后,针对一般6位置标定方法无法完成这一模型标定的缺陷,提出了一种18位置标定方法.进行标定后,运用显著性分析方法,对误差模型本身和其中的参数的有效性进行了分析.最后,通过重复进行去除最不显著项、再标定、显著性检验等步骤,获得了试验室条件下所能标定的捷联惯组加速度计组合误差模型.     

GPS-based sea level measurements to help the characterization of land contamination in coastal areas

The Corsica site has been established in 1996 to perform altimeter calibration on TOPEX/Poseidon and then on its successors Jason-1 and Jason-2. The first chosen location was under the #85 ground track that overflight the Senetosa Cape. In 2005, it was decided to develop another location close to Ajaccio, to be able to perform the calibration of Envisat and in a next future of SARAL/AltiKa that will flight over the same ground tracks. Equipped with various instruments (tide gauges, permanent GPS, GPS buoy, weather station…) the Corsica calibration site is able to quantify the altimeter Sea Surface Height bias but also to give an input on the origin of this bias (range, corrections, orbits, …). Due to the size of Corsica (not a tiny island), the altimeter measurement system (range and corrections) can be contaminated by land. The aim of this paper is to evaluate this land contamination by using GPS measurements from a fixed receiver on land and from another receiver onboard a life buoy. Concerning the altimeter land contamination, we have quantify that this effect can reach 8 mm/km and then affects the Sea Surface Height bias values already published in the framework of the Corsica calibration site by 5–8 mm for TOPEX and Jason missions. On the other hand, the radiometer measurements (wet troposphere correction) are also sensitive to land and we have been able to quantify the level of improvement of a dedicated coastal algorithm that reconciles our results with those coming from other calibration sites. Finally, we have also shown that the standard deviation of the GPS buoy sea level measurements is highly correlated (∼87%) with the Significant Wave Height derived from the altimeters and can be used to validate such parameter.     

雷达侦察系统近场相位校正方法的实现

对采用多基线相位干涉仪进行测向定位的雷达侦察系统,分析在近场条件下进行相位一致性校正时引入的波程差,提出了近场条件下的相位校正方法.该方法可有效地消除或减小环境因素对雷达侦察系统相位校正和测向误差的影响,从而提高测向和定位精度.     

对称联系组合定标法检测CMM空间误差

分析了现有三坐标测量机误差检测方法，提出了对称联系组合定标法。详细论述了该方法的测量原理及其简练新颖的数学模型，并通过实验比对，验证了该方法的正确性和实用性。     

新型浮动式收敛袋型密封自适应同心性能数值与实验研究

提出了新型浮动式收敛袋型密封结构，建立了新型收敛袋型密封数值求解模型，研究新型收敛袋型密封周向压力分布规律，分析进出口压比和偏心率对新型收敛袋型密封泄漏量及浮动同心力的影响。设计搭建了浮动式自同心密封实验台，在数值计算结果与实验测试结果相互验证的基础上，研究进出口压比和偏心率对新型浮动式收敛袋型密封泄漏量及自适应同心性能的影响。研究结果表明：在本文研究工况下，新型收敛袋型密封所产生的浮动同心力是传统迷宫密封的8.9~10.9倍。在不同进出口压比和偏心率下，传统浮动式迷宫密封均始终处于初始偏心位置，自适应同心性能较差。新型浮动式收敛袋型密封均向转子轴心方向移动，且随着进出口压比和偏心率的增大，浮动响应时间缩短，自适应同心性能增强。新型浮动式收敛袋型密封具有良好的浮动响应特性和自适应同心性能。     

迎角快速校准及误差对控制系统的影响研究

基于迎角传感器数据校准,目前所采用的线性插值算法对于测量区域的数值处理存在精度丢失的问题,采用三次曲线拟合以及神经网络逼近的方法实现对已有测量数据的精确映射,避免了由于二次映射引起的精度损失,同时提高了对于未测量区域的预测能力,保证了控制系统的跟踪性能。将校准方法通过两余度迎角校准系统进行了验证,并将校准系统加入动态逆飞行控制系统进行仿真,结果显示了算法的精确性和可靠性。     

被动式加载系统多余力的产生机理及其消除方法的研究

分析了被动式加载系统的工作特点；详细推导了被动式加载系统多余力的数学模型；探讨克服被动式加载系统多余力、提高加载精度的方法，为研制高性能的被动式加载系统提供理论依据。     

旋转环形截面弯管内粘性流动的摄动解

采用摄动方法求解了旋转环形截面弯管内的粘性流动，获得截面上轴向速度和二次流的二阶摄动解，系统地分析了主流速度、二次流动在科氏力和离心力共同作用下特性的变化情况；结果表明，当旋转方向和轴向速度方向相同时二次流强度将被加强；当旋转方向和轴向速度相反时，二次流涡结构变得复杂，环形截面上最多可出现八个涡，当科氏力和离心力之比F≈1．02时，二次流强度最弱。