Hydraulic piston pump in civil aircraft: Current status,future directions and critical technologies

The piston pump is the key power component in the civil aircraft hydraulic system, and the most common pump used in the aviation field is the pressure compensated variable displacement type. In this review paper, a basic introduction to the civil aircraft piston pump is presented, including the classification, structure, working principle, design features, and achievements by some research groups. Then, the future directions of the aircraft pump are reported from various perspectives. Further, the critical technologies are analyzed and summarized in detail from six thrust areas: friction couples, noise reduction, inlet boost, thermal management, fault diagnosis and health management, and mechanical seal. Finally, the challenges and limitations of the research on the aircraft pump are discussed to provide valuable insight for future scholars.     

Time-varying linear control for tiltrotor aircraft

Tiltrotor aircraft have three flight modes: helicopter mode, airplane mode, and transition mode. A tiltrotor has characteristics of highly nonlinear, time-varying flight dynamics and inertial/control couplings in its transition mode. It can transit from the helicopter mode to the airplane mode by tilting its nacelles, and an effective controller is crucial to accomplish tilting transition missions. Longitudinal dynamic characteristics of the tiltrotor are described by a nonlinear Lagrange-form model, which takes into account inertial/control couplings and aerodynamic interferences. Reference commands for airspeed velocity and attitude in the transition mode are calculated dynamically by visiting a command library which is founded in advance by analyzing the flight envelope of the tiltrotor. A Time-Varying Linear (TVL) model is obtained using a Taylor-expansion based online linearization technique from the nonlinear model. Subsequently, based on an optimal control concept, an online optimization based control method with input constraints considered is proposed. To validate the proposed control method, three typical tilting transition missions are simulated using the nonlinear model of XV-15 tiltrotor aircraft. Simulation results show that the controller can be used to control the tiltrotor throughout its operating envelop which includes a transition flight, and can also deal with vertical gust disturbances.     

民用飞机后机身参数化设计探究

通过对民用飞机后机身外形特征的分析,总结了民机后机身外形定义的关键参数,研究后机身外形参数化外形成型的可能性,提出了民机外形参数化设计的方法和思路。     

民航专业来华留学生现状分析及培养研究

通过对行业背景及来华民航专业留学生现状、教学方式、管理模式等方面的分析,提出了针对民航专业来华留学生的教学及管理方法。     

Earth observation with MEO transmitters and UAS receivers: A potential utilization of Galileo constellation

Remote sensing application of Galileo upcoming constellation in the field of civil security is preliminarily analyzed, defining low resolution (25 m) and high resolution (7.5 m) working modes for a bistatic Synthetic Aperture Radar system utilizing Galileo satellites as transmitters and Unmanned Aerial Systems as receivers. Simulations offshore Somali coast and in a South Mediterranean Sea region showed that both low and high resolution acquisitions are feasible. For the low resolution mode a probability of successful image formation no matter the azimuth position of the receiving UAS has been estimated at nearly 100%. Whereas, for the high resolution mode it decreases to about 90%, which, if deemed unsatisfactory for the application, leads to the need for UAS to adapt its route to the actual Galileo satellite coverage.     

民用小飞机取美国FAA型号合格证研究

洪都航空工业集团公司设计生产的N5A飞机先后取得中国民用航空局（CAAC）颁发的型号合格证和生产许可证。为了开拓国际市场,根据中美双边适航协议,按14CFR23适航标准与美国联邦航空局（FAA）小飞机管理中心达成的型号合格评估项目（CRI）要求,洪都集团主要从设计工程技术资料、持续适航文件、现场试飞评估等几个主要方面,接受FAA的审查,完成了FAA对该型飞机的颁证工作。本文结合该型飞机完整的型号取证过程,为我国航空工业企业按CCAR23部生产的小飞机申请美国FAA型号合格证,将产品推向国际市场探索出了一条可行之路。     

民事公益诉讼简释

公益诉讼源于罗马法,具有古老的历史,但民事公益诉讼存在的时间并不很长。本文尝试分析民事公益诉讼的内涵、特征,考查国外民事公益诉讼制度的状况以及我国民事公益诉讼的历史状况和现状。     

民用飞机RAT发电机自然结冰环境飞行试验研究

为了检验某型飞机RAT发电机在自然结冰环境下能否正常释放和供电,对该RAT发电机自然结冰试飞进行研究。首先,阐述RAT发电机进行自然结冰试飞的原因、目的以及民用航空标准对自然结冰环境的要求;其次,介绍RAT发电机自然结冰的试飞方法;最后,对试飞结果进行分析。结果表明:RAT发电机自然结冰环境条件满足适航规章要求,能够在可预期的自然结冰环境下实现手动释放功能且供电功能正常。     

Drop test and crash simulation of a civil airplane fuselage section

Crashworthiness of a civil airplane fuselage section was studied in this paper. Firstly, the failure criterion of a rivet was studied by test, showing that the ultimate tension and shear failure loads were obviously affected by the loading speed. The relations between the loading speed and the average ultimate shear, tension loads were expressed by two logarithmic functions. Then, a vertical drop test of a civil airplane fuselage section was conducted with an actual impact velocity of6.85 m/s, meanwhile the deformation of cabin frame and the accelerations at typical locations were measured. The finite element model of a main fuselage structure was developed and validated by modal test, and the error between the calculated frequencies and the test ones of the first four modes were less than 5%. Numerical simulation of the drop test was performed by using the LS-DYNA code and the simulation results show a good agreement with that of drop test. Deforming mode of the analysis was the same as the drop test; the maximum average rigid acceleration in test was 8.81 g while the calculated one was 9.17 g, with an error of 4.1%; average maximum test deformation at four points on the front cabin floor was 420 mm, while the calculated one was 406 mm, with an error of 3.2%; the peak value of the calculated acceleration at a typical location was 14.72 g, which is lower than the test result by 5.46%; the calculated rebound velocity result was greater than the test result 17.8% and energy absorption duration was longer than the test result by 5.73%.     

民用飞机增升装置中的流动控制技术

传统的增升装置设计受到各种约束条件的限制,难以充分发挥增升效果,甚至无法达到飞机对增升效果的需求,而流动控制技术可以弥补这些缺陷。通过搜集大量文献,阐述了襟翼涡流发生器、主翼后缘偏折技术、ZHU’s襟翼、自激励运动襟翼、零质量射流、等离子体技术、MEMS技术以及动力增升等各类主动控制技术的工作原理,增升效果分析以及具体应用情况等。结果表明,这些流动控制新技术对于进一步提高民用飞机的增升效果具有巨大的潜力。