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951.
小型涡喷发动机数控调节器的半实物仿真 总被引:5,自引:0,他引:5
介绍了某小型涡喷发动机数控调节器的半实物仿真试验系统的设计,以及软件和硬件的试验配置。半实物仿真试验对涡喷发动机控制系统的稳态和瞬态性能进行了校正和验证。试验完成了发动机数控调节器在地面和空中起动、停车功能的检验;自动加、减速功能,稳态调节性能的校正和校验;评价了发动机空中起动,按理论弹道飞行过程的调节性能。最后,给出了部分的仿真试验曲线。 相似文献
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《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2020,65(11):2586-2594
Precise point positioning with ambiguity resolution (PPP-AR) is a useful tool for high-precision geodetic and geophysical applications, while phase bias products are the prerequisite to implement PPP-AR. Wuhan University has been providing the final (the best operationally post-processing solution based) phase clock/bias products with a latency of two weeks since March of 2019, while a dedicated open-source software package PRIDE PPP-AR is released to leverage these products for high-precision positioning. In order to satisfy some both time and precision critical applications, such as rapid earthquake response, Wuhan University also released rapid (with comparable quality but with much shorter delivery latency) phase clock/bias products with a latency of less than 24 h and updated PRIDE PPP-AR in July 2019. We first introduce the phase clock/bias generation and validation schemes and the maintenance of routine products provision. Then, with 14 days (July 2 to July 15 in 2019) of GPS data collected from 146 globally distributed IGS (International GNSS Service) stations, we evaluated the positioning performance of the rapid products with respect to their final counterparts. It is found that positioning precision of PPP-AR using rapid products is comparable to that using final products, especially in kinematic positioning mode. When rapid products are used, the RMS of PPP-AR in static mode with respect to IGS weekly solutions can reach 1.7 mm, 1.8 mm and 5.5 mm in the east, north and up components, respectively. Furthermore, the RMS of epoch-wise positions with respect to daily solutions for the east, north and up components are 0.51 cm, 0.57 cm and 1.51 cm for PPP-AR with rapid products in kinematic mode. It demonstrates that the rapid phase clock/bias products can sufficiently meet the precision requirement of most geodetic and geophysical applications yet with much shorter time delay. Finally, we study the July 6th M7.1 2019 Ridgecrest, California earthquake using the rapid phase clock/bias products and demonstrate their comparable performance against the final products. 相似文献
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通过对三个单转子跨声速轴流压气机的数值模拟,考察了近失速点的流场特征.结果表明,Vo等人提出的尖峰型失速判别准则,即前缘溢流和尾缘倒流必须都出现则失速发生,并没有与本文所有箅例吻合;在部分算例中,尾缘倒流并未出现.因此,尾缘倒流是发生尖峰型失速的必要条件、还是失速发生后所导致的流动状况,还需要进一步研究.另外,还对亚声速和跨声速情况下近失速点的流场及流动机制进行了讨论. 相似文献
957.
Franz-Josef Ebert 《中国航空学报》2010,23(1):123-136
This article presents an overview of fundamentals of rolling element bearing designs and technologies. The aim is to outline the complex interrelation of all fundamentals with the rolling contact fatigue and the attainable bearing life. Such fundamentals include, amongst others, bearing stressing and life capability. The article shows the different types of rolling bearing stressing and the analysis of the stress distribution (principal stresses and equivalent stresses) in the material under the rolling contact area. It becomes obvious that the contamination of the bearing with foreign particles leads to a drastic reduction in bearing life. Furthermore, it demonstrates the impact of the bearing lubrication and coating as well as the effect of additives on the attainable life and wear. Further fundamentals of rolling element bearing design are the materials, the material cleanliness and the heat treatment. The article reveals the importance of the cleanliness of bearing steels as well as different types of inclusions and their effect on rolling contact fatigue. Additionally the article describes how to optimize the material properties (strength, toughness and residual stress) by the heat treatment processes. The outcome of these investigations is that endurance life of a rolling element bearing can be achieved if specific operating conditions, an adequate lubrication, good system cleanliness and specific bearing stressing are met. The article provides a guideline for bearing engineers on how designs and technologies can be applied to optimizing a bearing for a particular industry or aerospace application. 相似文献
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基于国内标准化文件类型单一及标准应用需求多样化的现状,调研了航天领域的国外相关7个标准化组织/机构发布的标准化文件类型及其定义解释,并采用对比分析和归类研究的方法进行了研究。基于文件的权威性、制定过程的规范性、内容的规范性综合分析,航天领域国外标准化文件概括起来主要包括4个类别:正式标准、不成熟标准、指南/手册、信息文件。此外,结合国内现状,提出了国内标准化文件类型多样性的建议,以期为用户提供多层次、全方位、更丰富的标准化信息,有助于用户对标准的理解及应用实施。 相似文献
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状态预测神经网络控制应用于小型可回收火箭 总被引:1,自引:2,他引:1
随着商业航天的到来,可重复使用运载器的研究受到广泛关注,以SpaceX为代表的商业航天公司研发的部分可回收火箭表现出了前所未有的竞争力。为了研发可回收火箭技术,翎客航天利用民间工业力量研制了RLV-T3小型可回收火箭验证机,并在该验证机上通过数百次试验逐渐掌握了垂直起降(VTVL)技术。主要介绍了翎客航天在VTVL技术中的一项动力控制技术,提出了状态预测神经网络控制(SPNNC)算法。该算法具有鲁棒性强、适用范围广、控制参数易调整等优点。详细地描述了该算法的原理,并通过Simulink对SISO和MIMO 2种系统进行了仿真。同时详细地论述了将状态预测神经网络控制算法应用于RLV-T3小型可回收火箭的飞行及回收的试验,包括RLV-T3小型可回收火箭的基本特点、控制难点、存在的问题,飞行过程中各物理量的曲线和试验结论。经试验验证,状态预测神经网络控制算法具有良好的控制性能,基于该控制技术,即状态预测神经网络控制算法的RLV-T3小型可回收火箭验证机可以安全地实现垂直起飞、弹道飞行、空中悬停、软着陆回收全流程。 相似文献