Journal of Civil Aviation University of China

Deviation of Beidou GBAS airborne receiver in final approach segment

LIU Ruihua, GAO Yi

2021, 39(4): 1-7.

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Deviation is an important performance indicator for airworthiness demonstration of GBAS (ground-based augmentation system) airborne receiver. According to the requirements of deviation outputs for GBAS airborne receiver DO-253D issued by RTCA (Radio Technical Commission for Aeronautics), the source of deviation is analyzed, the complete solution process of deviation is given, and the threshold of deviation is derived. Accordingly, the deviation outputs of Beidou-based GBAS airborne receiver are simulated and analyzed in static and dynamic scenarios. Simulation results show that the deviation outputs of Beidou-based GBAS receiver can meet the requirements of precision approach guidance outputs, which provides theoretical support for the formulation of GBAS airborne receiver airworthiness standards in China.

Numerical simulation analysis of different winglets under medium-high speed conditions

WANG Hui, CHEN Zezhou

2021, 39(4): 8-12.

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In order to study the drag reduction characteristics of different winglets, four types of winglets and winglet extensions are selected as the research objects. Under the same extended winglet and medium-high speed flight conditions (Ma = 0.6), five different winglet devices are numerically simulated using the k-ω SST (shear stress transfer) two-equation model. The pressure characteristics of the wing surface and the winglet flow field of five types of winglet are studied. The drag reduction characteristics of different winglet are compared and analyzed, along with the principle of induced drag changes. Research results show that the airflow guidance direction of different winglets the surface flow field of the wing and affects the winglet pressure distribution; under the conditions of medium-high speeds and with same wing length, the fused and raked winglets have better drag reduction effect, and the double-feathered winglet can effectively disperse the winglet vortex.

Application of point merge flight procedure in regional approach sector

HEI Yanru, WANG Zi, ZHANG Zhendong

2021, 39(4): 13-18.

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According to the basic concepts and methods of point merge flight procedure, the potential applicability of point merge in regional approach sectors is investigated. Data from the simulation platform of AirTOP and its performance evaluation show that point merge is applicable to regional approach sectors and can effectively improve the efficiency of approach flight flow.

Optimization of flight schedule of airport group based on flight procedure intersection

ZHAI Wenpeng, WANG Weiqing, YANG Qunting

2021, 39(4): 19-24.

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The concept of procedure intersection capacity constraint is proposed to optimize the flight schedule. Firstly, the flight procedure is adaptively selected, and the arrival time at the procedure intersection is reasonably controlled. Then, the flight schedule adjustment is reasonably allocated to the airlines in the airport group, and the flight schedule optimization model is constructed based on the simulated annealing algorithm. Taking flight schedule of the Yangtze River Delta airport group as an example, the simulation is verified by using the AirTOP simulation software. Results show that compared with the airport group flight schedule of traditional optimization model , the total amount of adjustment in this method has increased by 370 minutes, the average flight delay is reduced by 24.6%, and the number of controllers coordinating incoming flight conflicts is reduced by 46.3%, the capacity restriction of procedure intersection has effectively alleviated the aircraft aggregation near the conflict point and lowered the rate of the average flight delay.

Stability assessments of complex airways network for large airport

WANG Xinglong , XUE Yichen , AN Zhicai

2021, 39(4): 25-31.

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Assessing the stability of complex networks on large airport airways is of great significance for airway network design, emergency response, and flight delay reducing. Firstly, the airway network stability is defined. Then, based on the basic theories such as complex network and stability, the airway stability, node stability, city pair, hub airport indicators, flight delay data are collected, the stability evaluation index is determined based on the propagation delay distance, the number of delayed airports and the number of airport delays. A total of 35 airports with an annual passenger throughput of more than 10 million in 2018 are selected. The city-to-airway network and hub-airway network are respectively established. The airway delay statistics within a week are conducted and the evaluation indicators are calculated. Finally, statistical methods are used to compare and analyze the stability of airline network. Results show that under the same circumstances, the maximum numbers of the absolute delays of the city-to-airway network and the hub airway network are respectively 1 417 and 496. Thus the hub airway network is more stable than the city-to-airway network.

Numerical study of slit film cooling structure on turbine blade pressure surface

ZHOU Feng

2021, 39(4): 32-36.

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Film cooling is one of the most efficient cooling methods for turbine blades. A new type of slit cooling structure of turbine blades is proposed, numerical simulation is used to simulate the working process of turbine blades and the temperature and pressure parameters are obtained to analyze the effects of slit width, lip thickness and different machining positions on cooling efficiency and pneumatic loss. The results show that under the same incoming flow parameters, when the ratio of slit width to lip thickness is about 1.0, the new structure can achieve the best result; the top 60% of blade leading edge is the best machining position.

Optimization of line-replaceable unit list based on parking loss

XU Jianxin, GUO Ziqi, SHI Lizhong, FEI Yang

2021, 39(4): 37-41.

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By comparing time and money consumption of LRU (line-replaceable unit) and non-LRU parts in aircraft maintenance, a method to optimize the LRU list for airlines is proposed. FTA (fault tree analysis) is used to filter the faulty parts and sort troubleshooting sequences. Then, combining the 3D model data or detailed structure information of components, disassembly path with troubleshooting progress of faulty parts can be calculated. MODAPTS (modular arrangement of predetermined time standard) is used to estimate the time cost in maintenance task progress and calculate the parking loss during faulty part maintenance considering the operating status of airlines. For aircraft in service, the parking loss is compared with the cost of replacement unit to determine whether the strategy of replacing the LRU component is better for cost cutting; for aircraft type designers, the parking loss could be the reference for them to propose designing request to OEM(original equipment manufacture).

selection method of airport location based on GIS multi-factor weighted superposition

HE Yao, SHU Fumin, ZHENG Haowen

2021, 39(4): 42-47.

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In order to improve the scientificity of airport location, from the perspective of space suitability in airport site selection, geographic information system (GIS) is used to construct a multi-factor weighted and superimposed airport site selection space suitability model. The model organizes and integrates the data of the factors affecting the airport layout. After the data is rasterized and reclassified, the single-factor evaluation results are obtained. The analytic hierarchy process (AHP) is used to assign the influence weights of the factors, and the classification of suitable site selection area is formed by multi-factor weighted superposition. Taking the site selection of the second airport in Kunming, Yunnan Province as an example, the scientificity of the model is verified, and it can provide a new research idea for the site selection of airports.

Safety capability model of aircraft structure maintenance personnel

CHEN Fang , XU Bichen , MI Fengpei

2021, 39(4): 48-53.

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In order to study composition of the safety capability of aircraft structure maintenance personnel and provide basics for the evaluation in practical work, the task analysis process of aircraft structure maintenance personnel based on hierarchical task analysis (HTA) is established by employing the working characteristics of structure maintenance and consulting expert team. Then, Kelly repertory grid is used to conduct semi -structured interviews with expert team based on the HTA of aircraft structure maintenance personnel. Finally, Grounded Theory is used to encode the content obtained from the interview, and a model of the safety capability of aircraft structure maintenance personnel is constructed. Results show that the model includes three dimensions: structure maintenance capability, safety management capability and inherent characteristics. Among them, the inherent characteristics are potential factors that determine the structure maintenance capability. The structure maintenance capability is the external performance that determines the maintenance staff′s safety management capability that plays an auxiliary regulating role and is vital for the safety level improvement of the aircraft structure maintenance.

Fault simulation of electro-hydrostatic actuator system of aircraft considering nonlinear factors

YANG Jianzhong, LIU Ming, CHEN Xiyuan

2021, 39(4): 54-59.

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Electro-hydrostatic actuator(EHA) is a key component of flight control actuator system of civil aircraft. Its failure mode and effect are the focus of airworthiness certification and compliance verification. In current engineering practice, linearizing the components in the EHA system will ignore the influence of nonlinear factors in the system on the fault performance. Basing on AMESim simulation platform and considering the nonlinear factors of stiffness and connection clearance, EHA system nonlinear model is established. Simulation analysis is carried out to explore the influence of nonlinear factors such as stiffness and connection clearance on the leakage fault in hydraulic cylinder. Results show that stiffness reduces the magnitude of leakage fault in hydraulic cylinder but causes periodic vibration while stiffness has significant influence on the leakage in hydraulic cylinder. Nonlinear factors significantly affect EHA system failure performance, which provides technical support for airworthiness certification and compliance verification of EHA system.

Analysis of bridge vibration response under vehicle impact load

WANG Yadong , SHI Xingna

2021, 39(4): 60-64.

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Test on the mechanical properties of bridges under the moving loads of vehicles is one of the important aspects of bridge dynamic test. Considering the complex influence of the pavement roughness on the bridge dynamic test, this paper proposes a measuring technique of the crosstie vehicle′s bumping test which is aimed to suppress the pavement roughness. Firstly, based on the vehicle -bridge coupled vibration theory, the vibration equation is solved by numerical calculation method. The paper studies the factors that have significant influence on the bridge′s impact coefficient, such as the vehicle velocity and pavement roughness. Secondly, a vehicle bridge vibration system model under the condition of crosstie vehicle′s bumping is established. The calculation result shows the major factors which influence the bridge′s impact coefficient are vehicle speed and the height of vehicle′s bumping and pavement roughness. Analysis shows that the bridge′s impact coefficient follows Gaussian distribution on the same grade pavement, bringing significant changes on different grade pavements; the pavement roughness can be ignored when the vehicle speed and the height of vehicle′s bumping meet a certain condition. An engineering example shows that this model can accurately reflect the response of the simply supported beam under the impact load of the vehicle, and can be used to calculate the bridge′ s impact coefficient.

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