Table of Content

27 August 2020, Volume 38 Issue 4

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Civil Aviation

Flight tracking gap assessment based on multi-source heterogeneous data#br#

HAN Ping, ZHANG Bingqing, ZHANG Zhe, LU Xiaoguang

2020, 38(4):  1-6. 

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Aiming at the location report gap of ACARS or ADS-B during global flight tracking, a flight tracking gap assessment model is established based on the ACARS and ADS-B messages. Firstly, the model reconstructs the missing points by cubic spline interpolation algorithm, then divides the point coverage area and the missing area in the evaluation area. SVM algorithm based on Gaussian kernel function is used to obtain the tracking gap location probability distribution inside the missing area. Finally, test data are used to evaluate the model performance. Results show that the assessment model is suitable for two kinds of multi-source heterogeneous data, and the accuracy is higher with shorter data period.


GNSS spoofing detection algorithm based on composite SQM variance#br#

WANG Wenyi, GONG Jing

2020, 38(4):  7-12. 

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GNSS is vulnerable to spoofing and interference due to its open signal structure and weak signal power. SQM has been proved being able to detect spoofing attacks. However, due to the increasing variety of existing spoofing types, a single SQM algorithm in specific spoofing situations can no longer meet the need for real-time and high performance detection of spoofing attacks. A spoofing detection method is proposed to detect the change of composite SQM in the detection code tracking loop, which can detect the existence of spoofing based on the change of variance value of composite SQM and conduct experimental analysis with actual signals of TEXBAT.
Experimental results show that this method can detect spoofing attacks in a short time without increasing the complexity of the algorithm with better performance than that of the composite SQM algorithm.


Applicability study of HF loop antenna in civil aircraft#br#

CHEN Shihao, MENG Jian

2020, 38(4):  13-16. 

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Considering the performance requirements and design constraints of civil aircraft communication system on HF antenna, key technical indicators such as impedance features, efficiency, power capacity, radiation features and gain of HF loop antenna are analyzed by simulation. Basing on the analyzing results, the installation requirements of loop antenna are porposed. It is proved that loop antenna has flexible design and could be the optimal type of civil aircraft HF antennae.


Engine performance analysis under static uneven tip clearance#br#

CAO Huiling, WANG Han

2020, 38(4):  17-20，36. 

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Turbine tip clearance has great influence on engine performance. Borescope inspect image shows that the friction between the leading edges of HPT blade and shroud is severe, and the engine performance keeps low. It is found that the leading and trailing edges of HPT produce uneven expansion deformation under hot state. HPT leading edge grinding angle is adjusted in CFM56 aero -engine under static condition to produce uneven clearance between leading and trailing edges of blade tip position and to carry out the test. 3D turbulence numerical simulation is used to simulate the flow field of HPT and calculate its efficiency as well as thermal efficiency of the whole engine under working state. The key performance parameters are analyzed and the influence of static uneven tip clearance on turbine efficiency and engine performance is studied in combination with maintenance and test data. Result shows that the uneven tip clearance maintenance scheme can reduce the friction of shroud and effectively improve the performance of high-pressure turbine components and the engine.


Dynamic collision avoidance path planning of unmanned vehicles under airport bridge#br#

WANG Bingyuan, ZHENG Fang, LI Xia, JIANG Jian, YANG Bo

2020, 38(4):  21-26. 

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To optimize the path planning duration and smooth planning path for dynamic collision avoidance of unmanned vehicle, a fusion algorithm for path planning is proposed. Bid -RRT is used to quickly search the obstacle avoidance path, shorten the path planning time. Dynamic window approach is used to smooth the planning path,the path planned by the fusion algorithm is able to avoid collision of unmanned vehicles under dynamic constraints. Simulation results show that the planned trajectory is more secure and more effective for dynamic collision avoidance of unmanned vehicles under airport bridge, being able to conduct collision avoidance path planning both rapidly and smoothly.


Design of six-DOF attitude simulation system for flight simulator#br#

DU Hanghang

2020, 38(4):  27-30. 

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A six-DOF platform is designed employing the control algorithm of Stewart爷s six-DOF parallel mechanism.Flight attitude data is converted into the actuator motion parameters through inverse kinematics to drive servos.The flight attitude data of Prepar 3D the simulation flight software can be obtained through shared memory and then imported into the simulation platform to conduct verification. Results show that the attitude simulation platform has high motion precision and stability and can be used for theoretical verification.


Design of visualized airline operation system based on system integration#br#

TAN Zhaoyang

2020, 38(4):  31-36. 

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In order to improve the safe operation level of airlines, a monitoring platform of airline operation is built based on information integration and sharing. Influential factors of each flight such as operating environment, operating status, aircraft status, and flight crew capacity are monitored and with emergency warning. Thus the system can achieve operational flight risk control, hidden danger elimination and hazardous disposal, realize systemization and automation of flight operation monitoring and can be applied to various business areas.


Flight delay short-term prediction based on improved ICEEMDAN#br#

WANG Hui, CHEN Chao

2020, 38(4):  37-42. 

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Aiming at the difficulty in short-term accurate prediction of flight delay, a combined flight delay prediction model based on improved denoising method of ICEEMDAN and support vector machine (SVM) is built. Firstly, the original flight delay sequence is decomposed into stationary components by using ICEEMDAN algorithm, and then the mixed noise in the component is determined by correlation function analysis and is processed by SG filtering. Secondly, the SVM regression prediction model is established for each component according to its features; predicted values of each Component model are superimposed to obtain the final predicted data. Compared with the ICEEMDAN-SVM model, the improved combined prediction model reduces the root mean square error and mean absolute percentage error by 8.7% and 11.9% respectively, proving that the model has good following ability to flight delay sequence fluctuation and strong generalization capacity.


Airport safety risk assessment under of large-scale flight delay#br#

ZHANG Li, QI Xiaoyun, WANG Xiaochun

2020, 38(4):  43-47. 

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In order to improve the safety risk management level of large-scale flight delays for the airport. Based on the traditional assessment index of airport safety risk and the impact of large-scale flight delays, it obtained the safety risk evaluation index of large-scale airport flight delays, and build a network model by ANP method; in order to reduce subjective error of experts scoring, it increased the reliability of weight in the evaluation model by using the experts mean confidence act; it obtained the quantitative sort of index weight of airport safety risk assessment using the SD software. The results showed that: intact rate of facilities and equipment, perfect rate of facilities and equipment, illegal operation rate of employee, supervision error rate of safety staff, emergency education and training are the most important factors of risk sources.it provided the theoretical basis for the airport safety risk management in the situation of large-scale flight delays.


Development and challenges of supercooled large drop icing research for civil airplane airworthiness certification#br#

LI Yanxin, GU Xin

2020, 38(4):  48-53. 

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In order to implement the research of supercooled large droplet(SLD) icing airworthiness verification, the SLD icing research progresses in and abroad have been systematically summarized from the following three aspects: the microscopic mechanism of SLD anomaly icing, the evaluation method of flight performance after icing, and the safety protection technique of SLD icing. Then, basing on the common thoughts of civil aircraft icing airworthiness certification under conventional icing conditions, the airworthiness certification approaches of SLD icing are explored. Finally, looking ahead to the future challenges for SLD icing research and certification approaches, promoting suggestions are proposed including the combination of theoretical research and engineering practice, enhancement of verification capacity under critical condition and building of SLD icing airworthiness standards and procedure, helping break bottlenecks and solve the key problems of civil aircraft development.


Low-altitude helicopter flight data simulation#br#

XU Yusong, GE Hongjuan, XUE Jianliang, NI Youyang

2020, 38(4):  54-59. 

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Current helicopter operation data cannot meet the needs of safety monitoring research. Based on C ++ and Simulink, a low-altitude helicopter flight data simulation system is established to simulate the key operational data such as flight control, avionics, and engines under different atmospheric wind environments. Simulation results show that the trimming data in the stable forward flight state has small deviation from the actual operational data. The system has high simulation accuracy. The proposed system can accurately simulate helicopter operational data under specific flight scenarios such as gusts, helping to solve the lack of helicopter safety monitoring data.


Engineering and Technology

Flat contact model with rounded edges and finite element analysis#br#

ZHANG Hanyu, XU Wenjun

2020, 38(4):  60-64. 

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When calculating the response of the turbine blades with a dry friction damper, the tangent contact stiffness between the contacts of the damper affects the conditions of the contact state conversion directly. In this paper,theoretical derivation was combined with numerical simulation method. By establishing a flat contact model with rounded edges, the force distribution of the contact surface was given. Based on the displacement distribution of contact points, the relationships between tangent contact stiffness and normal pressure was derived. Besides, the relationship between contact stiffness and normal pressure was obtained by finite element simulation as well.Therefore, we can obtain the contact stiffness quickly and accurately to more accurately analyze the state changes between combined surfaces.