Table of Content

09 April 2025, Volume 43 Issue 1

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Safety and airworthiness of civil aircraft

Sensitivity analysis of engine safety affecting factors based on the turbocharging

system model

LI Guoa, , WANG Zilub , TENG Yidab , XU Tonggeb

2025, 43(1):  1-10. 

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Adopting turbocharging system can effectively restore the high-altitude power performance of the engine and improve the working ceiling of general aircraft. However, while improving the engine performance, its safety should

also be given sufficient attention. In order to improve the safety of the turbocharging system of aviation reciprocating engine and provide suggestions for actual operation, this paper combines model-based system safety analysis,

"V" shaped safety analysis, response surface methodology (RSM), and Sobol factor sensitivity analysis method, and

taking Rotax914 as prototype, a quasi dimensional model for the entire engine and fitting equation are constructed

for global sensitivity analysis. The sensitivity of the turbocharging system performance of aviation reciprocating engine to different safety affecting factors are analyzed and compared. The results indicate that the sensitivity index of

altitude is much higher than other factors, and the sensitivity index of intake valve diameter is higher than that of

exhaust valve diameter but they are similar in magnitude. The effective length of air filter has almost no effect on the

engine turbocharging system under normal operating condition. Therefore, during the actual operation, the change

range of safety affecting factors can be adjusted according to the analysis results, in order to reducing the uncertainty of key factors and conducting efficient and intuitive safety analysis.

Determination and verification of severe anti-icing working conditions

during the entire flight phase

HU Xuelan, WANG Yidan, NIU Yifan, YAO Jiawei

2025, 43(1):  11-19. 

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Determining the severe working conditions that meet the airworthiness requirements is a necessary step in the airworthiness certification process of wing icing, and traditional calculation methods of severe anti-icing working

conditions require a large amount of repetitive calculations, therefore, this article proposes a simplified method for

determining severe working conditions based on Appendix C of CCAR-25 (Appendix C) by combining Latin hypercube sampling and severity assessment index, considering the entire flight phase and full ice accumulation

conditions, and its feasibility is verified by computational fluid dynamics model. Firstly, based on Appendix C, the

parameter intervals for icing working conditions were clarified, and Latin hypercube sampling was used to discrete

the continuous parameter intervals and obtain the combined working conditions. Secondly, the severity assessment

index is introduced to rank the icing working conditions, and the computational fluid dynamics simulation calculation of wing icing under univariate icing working conditions and continuous maximum icing working conditions is

used to verify that the severity assessment index can be used as an evaluation index for severity assessment under

the same ice type, with the amount of icing (including the total mass of icing and the maximum icing thickness). It is

proved that the larger the absolute value, the more severe the working working conditions. Due to the significantly

longer flight time compared to other flight phases, the waiting phase has the highest degree of icing severity, and all

severe working conditions are in the waiting phase. Finally, the severe condition based on Appendix C are given by

the severe condition determination method proposed in this paper.

Study on the influence of different loading conditions on lumbar response index

RUI Xiangqian , CUI Shurui a , SHI Xiaopengb

2025, 43(1):  20-26. 

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Lumbar load and dynamic response index (DRI) are two common lumbar response index used to assess passenger

lumbar injuries during emergency landing of aircraft. To elucidate the differences between these two metrics, firstly,

the seat-occupant finite element model and the occupant upper limb lumped parameter model were established in

this paper. Secondly, a comparative verification is conducted between the seat-occupant finite element model and

the occupant upper limb lumped parameter model. Finally, a parametric analysis was conducted on these two lumbar response index by changing the loading time and loading peak value. The results show that the DRI value calculated by floor acceleration is lower than that calculated by pelvic acceleration, and when the loading time is constant, the DRI value shows an increasing trend with the increase of loading peak value. When the loading peak value is constant, the DRI value shows the trend of increasing first and then decreasing with the increase of loading

time. When the speed change is constant, the DRI value shows an increasing trend with the increase of the loading

peak value. In summary, by sorting out and analyzing the principle of DRI, it is helpful to promote the continuous

improvement of the criteria for determining occupant lumbar injuries.

Study on degradation and thermal runaway characteristics of commercial

lithium-ion battery fast-charging

ZHOU Xiaomeng a, b , CAI Jinlea, b , GUO Yiboa , LIAO Yunlong b

2025, 43(1):  27-32. 

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To identify the impact of fast-charging aging factors on the operation and thermal safety performance of lithium-ion

batteries, this study first conducts cyclic aging tests on commercial 18650 lithium-ion batteries using 1C/2C charging rate to characterize capacity decay, electrochemical impedance, operating temperature rise, and other characteristics of the battery. Secondly, on the self built thermal runaway platform, compare the differences in thermal runaway behavior and temperature characteristics between fresh and fast-charging aged lithium-ion batteries are compared. The results show that the aging process of lithium-ion battery is nonlinear, and presents three stages corresponding to different aging mechanisms. Increasing the fast-charging rate leads to a significant magnify in charge

transfer impedance and ohmic impedance. The cycle life of lithium-ion batteries with 2C charging rate aging shortens rapidly, and abnormal heat release behavior occurs during the cycle, and the maximum surface temperature reaches 75 ℃ during the charging phase, which not only accelerates the capacity decay of the battery, but also increases the risk of thermal runaway. The results of the thermal runaway test show that the thermal runaway of aged

lithium-ion batteries is delayed and the temperature of thermal runaway is higher. Lithium-ion batteries affected

by fast-charging aging factors have better thermal stability, but the process of thermal runaway is more dangerous.

Aerodynamics

Numerical study of the effect of boundary layer ingestion on the flow field

distortion of S-shaped intake

FU Wenguang, XIAO Lei, SUN Peng

2025, 43(1):  33-40. 

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: In order to study the effect of boundary layer ingestion (BLI) on the flow field distortion of the S-Shaped intake, a

short spread pressure and small offset S-shaped intake is designed in this paper, the effect of BLI on the flow field

characteristic of S-shaped intake is analyzed, and the effect of inhaling boundary layers of different thicknesses on

the outlet flow field is further researched. The results show that when the boundary layer is inhaling, the three-dimensional separation flow of the fluid inside the inlet forms a twin swirl distortion zone, low-energy fluid accumulated at the bottom of the intake tract, and forms a unique concave shape total pressure distortion zone at the exit

position. With the increase of the thickness of the suction boundary layer, the flow capacity of the inlet tract decreases, and the total pressure distortion intensity and range at the outlet section increase. However, the range of

swirl distortion slightly increases, and there is no significant change in swirl intensity.

Research on influence of geometric parameters of airfoil on aerodynamic

characteristics of ducted coaxial double rotors

YANG Yonggang a , ZHENG Wei b

2025, 43(1):  41-46. 

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The geometric parameters of the airfoil have a great influence on the aerodynamic characteristics of the rotor. This

article focuses on numerical simulation calculations of the ducted coaxial double rotors model, studying the influence of different geometric parameters on the aerodynamic characteristics of the rotor, in order to improve the aerodynamic efficiency of the ducted coaxial double rotors. The results indicate that increasing the airfoil camber and

the installation angle of the blade root can significantly improve the total thrust of the ducted coaxial double rotors.

When the thrust coefficient is less than 0.04, the aerodynamic performance parameters of the small camber airfoil

were higher than those of the large camber airfoil. As the thrust coefficient continues to increase, aerodynamic interference and vortex trajectory disorder occurred between the lip airflow of the duct and the tip vortex of the upper

rotor, as well as between the wakes of the double rotors. Local flow separation occurred on the inner wall surface of

the duct outlet. These are the main reasons for the rapid decline of aerodynamic performance parameters of small

camber airfoil. The aerodynamic performance parameters of the large camber airfoil change smoothly, and the aerodynamic efficiency is better than that of the small camber airfoil when the thrust coefficient is large. It is a better

choice to design the rotor with a blade root installation angle for NACA6412 between 20° to 40°.

Aeronautical communications and navigation

ADS-B signals separation algorithm based on cluster weighted covariance matrix

WANG Wenyi , ZHANG Hanshuo

2025, 43(1):  47-52. 

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The automatic dependent surveillance - broadcast (ADS-B) systems transmit ADS-B signals by randomly broadcasting in the same frequency band, which will lead to the overlapping of ADS-B signals and threaten aviation safety. At present, when Capon algorithm is used to separate ADS-B signal, the pulse characteristics of ADS-B signals are not taken into account, which will greatly degrade the performance of Capon algorithm. Therefore, this paper designs a signal separation algorithm based on cluster weighted covariance matrix for ADS-B overlapping signals. Firstly, the characteristics of the array response of ADS-B signal are analyzed according to its pulse characteristics. Then, three types of snapshots with only noise, only the first signal and only the second signal are screened

out by K-means clustering method. The covariance matrix of these three types is calculated respectively. Secondly,

the covariance matrix of noise snapshots and the covariance matrix of the signal to be suppressed are selected and

the sum of them is calculated to replace the covariance matrix estimated by all snapshots in the objective function of

Capon algorithm. Finally, combined with the Capon algorithm, overlapping ADS-B signals can be separated. The

results show that this algorithm can significantly improve the performance of ADS-B overlapping signals separation.

Integrity evaluation based on intelligent estimation of ionospheric delay

LU Dan, ZHANG Hongjian, ZHONG Lunlong, HU Tieqiao

2025, 43(1):  53-59. 

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Integrity is one of the performance requirements of civil aviation navigation systems, and ionospheric delay is an

important error source for integrity evaluation. For the single-frequency system, Klobuchar model is usually used

to correct the single-frequency signal, but the correction rate is only about 60%, and the accuracy is limited. This

paper proposes a method for estimating ionospheric delay and using it for integrity evaluation. Firstly, the ionospheric delay of observation station is trained by back propagation (BP) neural network, and the ionospheric delay

is calculated by BP neural network model of the observation station, which improves the ionospheric delay correction rate of the observation station. Secondly, the ionospheric delay of the aircraft equipped with single-frequency

receiver at its flight position is calculated by using the trained observation station BP neural network model and the

three-point interpolation method, and the integrity evaluation is carried out. Evaluation based on the data from

February to March 2015 shows that, when calculating the ionospheric delay, the BP neural network model and the

three-point interpolation method perform better than the Klobuchar model in some areas. They improve the correction rates of ionospheric delay during both daytime and nighttime, thus enhancing the accuracy of the protection level.

Aviation maintenance

MSCNN-LSTM method for monitoring the state of horizontal stabilizer system

based on flight data

ZHANG Penga , HU Fangyub , DUAN Zhaobina , LIU Jingjingb

2025, 43(1):  60-66. 

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To address the problems of insufficient fault samples, imbalanced data classes and lack of labeling in real flight data, a state monitoring method for a horizontal stabilizer system based on multi-scale convolutional neural network

(MSCNN) and long short-term memory (LSTM) network is proposed in this paper. This method does not rely on labeled data and uses unsupervised learning to monitor the state of the horizontal stabilizer system. Firstly, the quick

access recorder (QAR) data of the system in normal operation are extracted in both spatial and temporal dimensions

using MSCNN-LSTM to achieve rudder position prediction. Secondly, the residuals between the predicted and actual values of the rudder position are calculated and the distribution of the residuals is analyzed to determine the

threshold for the health state of the system. Finally, the QAR data of an aircraft is used for verification, and the experimental results show that the proposed method in this paper can accurately achieve the abnormal state identification of the horizontal stabilizer system at the flight level and can provide an abnormal alarm one flight cycle in

advance when system failure occurring.

Research on the performance monitoring and replacement standard for damaged

hydraulic hose of civil aircraft

JIA Baohui a , MA Yuwei b , WANG Yuxina , YAO Fei b , XIAO Haijianc

2025, 43(1):  67-74. 

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Using the approach of theoretical model establishment, experimental verification and simulation analysis, the mechanical performance change rule and failure situation of the hydraulic hose of civil aircraft when containing wear

defects are analyzed in this paper. The damage status of the hose that needs to be key monitored and the wear defect

depth recommend for replacement are obtained. Based on the flow-solid coupling method, a finite element simulation analysis of composite pipeline was conducted in ANSYS WORKBENCH to explore the influence of wear defect

depth and axial length on mechanical performance under different fluid pressures, the prediction function relationship of the maximum total deformation and maximum equivalent strain of pipelines under different pressures are

given, and a composite strength model of damaged pipelines is established. According to the established model, the

pipeline does not fail before the inner wall is completely damaged, and when the wear depth and wall thickness ratio is 0.4, its mechanical performance decrease significantly, when it needs to be key monitored or replaced.

Study and prediction of the effect of aviation grounded faults arc damage

ZHANG Tiechun , LIAO Maoqiao , ZHANG Bo , TIAN Leilei , SI Xiaoliang

2025, 43(1):  75-82. 

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Arc fault is one of the most common failure modes in aircraft electrical wire interconnect systems (EWIS). In order to

study the impact of different condition parameters on the arc damage, this paper simulated the grounded fault arc of

wire harness and fuel pipeline caused by aircraft vibration according to the vibration experimental method in SAE

AS5692 standard. The experimental research on grounded fault arc damage was carried out under the conditions of

airborne 28 V direct current (DC) power supply and 400 Hz/115 V alternating current (AC) power supply. And based

on the numerical computation method of fluid-solid thermal coupling, an arc damage prediction model was established. The results show that the arc under AC power conditions has a shorter wire harness melting time due to

higher instantaneous power compared to DC power conditions, and its arc damage is significantly smaller than that

under DC power conditions. As the vibration frequency increases, the contact time between the wire harness and

the pipeline is prolonged, and the arc damage is positively correlated with the vibration frequency. Comparing the

experimental and simulation results, the error between the two is relatively small, which effectively verifies the applicability of the arc damage prediction model and provides a certain reference for the safety assessment of the aircraft EWIS wire harness.

General aviation and drones

Safety assessment and decision analysis of UAV considering uncertainty

TIAN Yi, RAO Haochang, XIAO Nyu′e

2025, 43(1):  83-88. 

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Quantitative safety assessment is an important means to verify whether unmanned aerial vehicle(UAV) meets the

safety requirements. Aiming at the parameter uncertainty of UAV component failure distribution, firstly, the failure

distribution parameters of basic events are modified by Bayesian theory to obtain the failure probability of top

events. Then, the safety decision analysis of top events is completed with the help of Bayesian decision theory. Finally, the safety evaluation of UAV is improved into a complete assessment and decision analysis process. The research shows that the calculation process of top event failure probability and Bayesian decision can be realized by

taking the error information generated by data link communication during the operation of a UAV as an example.

Route planning of urban logistics UAV based on improved artificial fish

swarm algorithm

YUE Rentian , HOU Bowen

2025, 43(1):  89-96. 

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In order to safely and efficiently solve the problem of three-dimensional spatial route planning for logistics unmanned aerial vehicles (UAV), this paper first models the planning environment by improving the grid method

based on spatial obstacle avoidance and ground population density. The route planning model for logistics UAV is

established with the objective function of minimizing the sum of distance cost, grid risk value cost and height adjustment cost, and constraints are set according to UAV performance. Secondly, the standard artificial fish swarm

algorithm (AFSA) is improve by adding fish swarm jumping behavior and grid taboo table, and the improved AFSA

is employed to solve the model. Finally, the improved AFSA was compared with three other algorithms through

simulation examples and parameter sensitivity analysis was conducted on the improved AFSA. The results show

that the improved AFSA had better convergence speed than the other three algorithms, with a 9.9% reduction in

convergence time compared to the standard AFSA. Setting larger perception range parameter values resulted in

higher efficiency in route planning, while the step size parameter need to be adjusted according to the planning environment. The improved AFSA can provide reference for improving the efficiency of logistics UAV three-dimensional spatial route planning.