Tianyu Gong, Yiqing Li, Feng juan Wei, Shiqichang Wu, Dehua Cao
Bleeding is an effective method to improve the starting performance of the inlet, and the conventional method often adopts the bleeding to longitudinal direction. This article proposes the use of transversal bleeding method to explore the influence on starting capacity by changing the bleeding direction. The paper designs 6 bleeding inlets. By calculating the starting performance, it is found that the projected bleeding rate of the inlet, which is the direct factor influencing the starting performance, would change due to the direction change of bleeding, although designed with the same entrance. For the inlet designed with longitudinal slots and bleeding, it could reach the starting state at Mach 3.6, but it showed the unstart state when they are transversal direction. The same entrance, when inlet is designed by transversal bleeding with longitudinal slots, the starting Mach number would decrease to 3.8. For the changes of aerodynamic capabilities, there would be the “point jump” tendency when reaching starting state, but the same inlets would keep the similar performance when they get the starting state.
{"title":"The Influence of Bleeding Direction on Starting Performance of Three-Dimensional Inward Turning Inlet","authors":"Tianyu Gong, Yiqing Li, Feng juan Wei, Shiqichang Wu, Dehua Cao","doi":"10.1155/2023/9378776","DOIUrl":"https://doi.org/10.1155/2023/9378776","url":null,"abstract":"Bleeding is an effective method to improve the starting performance of the inlet, and the conventional method often adopts the bleeding to longitudinal direction. This article proposes the use of transversal bleeding method to explore the influence on starting capacity by changing the bleeding direction. The paper designs 6 bleeding inlets. By calculating the starting performance, it is found that the projected bleeding rate of the inlet, which is the direct factor influencing the starting performance, would change due to the direction change of bleeding, although designed with the same entrance. For the inlet designed with longitudinal slots and bleeding, it could reach the starting state at Mach 3.6, but it showed the unstart state when they are transversal direction. The same entrance, when inlet is designed by transversal bleeding with longitudinal slots, the starting Mach number would decrease to 3.8. For the changes of aerodynamic capabilities, there would be the “point jump” tendency when reaching starting state, but the same inlets would keep the similar performance when they get the starting state.","PeriodicalId":13748,"journal":{"name":"International Journal of Aerospace Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-08-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47524970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, the average effects of the Lorentz acceleration on the charged spacecraft’s orbit are studied encounter with relativistic correction. The relativistic correction as function of the orbital elements, and may be time, is formulated. Lagrange planetary equations are used to calculate the perturbations due to considered perturbing forces. The needed conditions to neutralize the effects of the relativistic corrections, using Lorentz acceleration, are derived. Numerical examples for different kinds of orbits are applied.
{"title":"Balancing Conditions for the Relativistic Correction Using Lorentz Acceleration","authors":"M. A. Yousef, M. El-Saftawy, A. Mostafa","doi":"10.1155/2023/5593887","DOIUrl":"https://doi.org/10.1155/2023/5593887","url":null,"abstract":"In this work, the average effects of the Lorentz acceleration on the charged spacecraft’s orbit are studied encounter with relativistic correction. The relativistic correction as function of the orbital elements, and may be time, is formulated. Lagrange planetary equations are used to calculate the perturbations due to considered perturbing forces. The needed conditions to neutralize the effects of the relativistic corrections, using Lorentz acceleration, are derived. Numerical examples for different kinds of orbits are applied.","PeriodicalId":13748,"journal":{"name":"International Journal of Aerospace Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46892481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The presented study offers a comprehensive insight in design and application of the Kalman filters for improvement of control efficiency of small unmanned aerial vehicles with fixed wing. The presented control scheme of the UAV includes its model, a servo drive model, and an optimal proportional-integral-derivative (PID) controller for the selected flight speed. Subsequently, process noise and measurement noise components were introduced into the whole constructed UAV model. The process noise was formed by disturbances caused by horizontal and vertical airflow in the atmosphere. The measurement noise contained deterministic and stochastic errors of the inertial measurement unit (IMU) UAV sensors and engine noise. The obtained results showed that the designed optimal Kalman filter was able to eliminate the influence of interfering signals from the control process and increased the phase safety, controllability, and stability of UAV control as a lean design can be applied in real-time control systems like Pixhawk PX4.
{"title":"Reduction of the Influence of Interfering Signals on the Longitudinal Control of UAVs with Fixed Wing","authors":"R. Bréda, Š. Karaffa, R. Andoga, M. Hlinková","doi":"10.1155/2023/9252640","DOIUrl":"https://doi.org/10.1155/2023/9252640","url":null,"abstract":"The presented study offers a comprehensive insight in design and application of the Kalman filters for improvement of control efficiency of small unmanned aerial vehicles with fixed wing. The presented control scheme of the UAV includes its model, a servo drive model, and an optimal proportional-integral-derivative (PID) controller for the selected flight speed. Subsequently, process noise and measurement noise components were introduced into the whole constructed UAV model. The process noise was formed by disturbances caused by horizontal and vertical airflow in the atmosphere. The measurement noise contained deterministic and stochastic errors of the inertial measurement unit (IMU) UAV sensors and engine noise. The obtained results showed that the designed optimal Kalman filter was able to eliminate the influence of interfering signals from the control process and increased the phase safety, controllability, and stability of UAV control as a lean design can be applied in real-time control systems like Pixhawk PX4.","PeriodicalId":13748,"journal":{"name":"International Journal of Aerospace Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42749298","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A satellite is considered to be moving relative to a nominal elliptical orbit, whose dynamics are usually described by the Tschaunner-Hempel equation (T-H equation). In this paper, we propose to transform the second-order time-varying system represented by the linear T-H equation with a second-order matrix form into a first-order time-varying system. Then, the controllability of the first-order time-varying system is investigated with the matrix sequence method including e = 0 . Meanwhile, we study the observability of the first-order time-varying system with a specific form of measurement. The advantages of the matrix sequence method for controllability and observability analysis are tested by numerical examples, respectively. Dual theory is used to investigate the controllability and observability of the corresponding dual system of the T-H equation. The corresponding conclusions are obtained.
{"title":"Controllability Analysis of Linear Time-Varying T-H Equation with Matrix Sequence Method","authors":"Sihui Liu, Qingdao Huang","doi":"10.1155/2023/1981979","DOIUrl":"https://doi.org/10.1155/2023/1981979","url":null,"abstract":"A satellite is considered to be moving relative to a nominal elliptical orbit, whose dynamics are usually described by the Tschaunner-Hempel equation (T-H equation). In this paper, we propose to transform the second-order time-varying system represented by the linear T-H equation with a second-order matrix form into a first-order time-varying system. Then, the controllability of the first-order time-varying system is investigated with the matrix sequence method including \u0000 \u0000 e\u0000 =\u0000 0\u0000 \u0000 . Meanwhile, we study the observability of the first-order time-varying system with a specific form of measurement. The advantages of the matrix sequence method for controllability and observability analysis are tested by numerical examples, respectively. Dual theory is used to investigate the controllability and observability of the corresponding dual system of the T-H equation. The corresponding conclusions are obtained.","PeriodicalId":13748,"journal":{"name":"International Journal of Aerospace Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47564729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
For the problem of spacecraft attitude actuator failure, an adaptive terminal sliding mode fault-tolerant controller (ATSMFTC) based on the differential manifold SO(3) modelling is designed in this paper. First, SO(3) is used to provide a global and unique description of the spacecraft attitude dynamic model. This modelling method not only avoids the problems of singularity and unwinding that exist in traditional modelling methods but also the SO(3) modelling has a simple formulation of the dynamic equations. Then a left attitude error descriptor function is constructed on SO(3) to design an ATSMFTC. This controller is capable of fast and accurate tracking of the time-varying desired attitude. At the same time, it can react quickly to maintain system stability in case of spacecraft attitude actuator failure. The controller designed based on the left attitude error description system of SO(3) has the features of small computational effort and simple design process. Finally, the numerical simulation of the attitude tracking error verifies the feasibility and high efficiency of the controller designed in this paper.
{"title":"Adaptive Terminal Sliding Mode Fault-Tolerant Control of Spacecraft Based on the Left Attitude Error Function of SO(3)","authors":"Zhongzhong Zheng, Wei Shang, Zhou Liu, Yong Guo","doi":"10.1155/2023/1983417","DOIUrl":"https://doi.org/10.1155/2023/1983417","url":null,"abstract":"For the problem of spacecraft attitude actuator failure, an adaptive terminal sliding mode fault-tolerant controller (ATSMFTC) based on the differential manifold SO(3) modelling is designed in this paper. First, SO(3) is used to provide a global and unique description of the spacecraft attitude dynamic model. This modelling method not only avoids the problems of singularity and unwinding that exist in traditional modelling methods but also the SO(3) modelling has a simple formulation of the dynamic equations. Then a left attitude error descriptor function is constructed on SO(3) to design an ATSMFTC. This controller is capable of fast and accurate tracking of the time-varying desired attitude. At the same time, it can react quickly to maintain system stability in case of spacecraft attitude actuator failure. The controller designed based on the left attitude error description system of SO(3) has the features of small computational effort and simple design process. Finally, the numerical simulation of the attitude tracking error verifies the feasibility and high efficiency of the controller designed in this paper.","PeriodicalId":13748,"journal":{"name":"International Journal of Aerospace Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-08-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43708132","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cycle slip determination plays an important role in high-precision data processing and application of global navigation satellite systems (GNSS). The TurboEdit method consists of the Melbourne-Wubbena (MW) and the geometry-free phase (GF) combination. It can correctly detect and repair cycle slip in most cases. Cycle slip detection (CSD) with GF is disturbed by severe ionospheric delay variations; moreover, CSD or cycle slip repair (CSR) with the MW faces the risk of the disturbance from large pseudorange errors. Hence, cycle slip determination would be difficult under some extreme conditions, e.g., cycle slips occur in low altitude satellite, low sampling rate of dual-frequency observations. To overcome the limitations, a new dual-frequency CSD and CSR method is proposed. The main contents are as follows: (1) compared with the MW method, the Doppler-assisted phase subtraction pseudorange (DAPSP) method that we proposed has no detection blind spot and can effectively reduce the influence of pseudorange noise at high sampling rates; thus, we replace MW by the DAPSP method to improve the detection accuracy. (2) An adaptive threshold model with root mean square (RMS) is established to effectively reduce the missing and false range detection of cycle slip. (3) The sliding polynomial fitting-assisted GF (SPFAGF) is carried out according to the satellite altitude angle. The trend of ionospheric delay and residual multipath effect error between adjacent epochs is extracted and suppressed by SPFAGF. The method combined with DAPSP and SPFAGF (DAPSP-SPFAGF) overcomes the situation that the TurboEdit method cannot effectively detect under extreme conditions. The experimental results of Beidou dual-frequency observation data show that the TurboEdit method and the DAPSP-SPFAGF method can perform CSD and CSR in most cases. At the sampling rate of 1 s, the detection speed of DAPSP-SPFAGF method is significantly faster than TurboEdit method. The number of false positives about CSD is reduced from 68 to 0. At the sampling rate of 30 s and under the condition of the observed satellite altitude angle below 30°, the false alarm rate of the DAPSP-SPFAGF method is 0, but the TurboEdit method’s false alarm rate is 71.2%. So DAPSP-SPFAGF method is prior to the TurboEdit method at the high sampling rates or under extreme conditions, especially it can accurately detect and repair cycle slip and reduce the false positives and false alarm rate.
{"title":"A Modified Cycle Slip Detection Method with GNSS Doppler Assistance and Optimizing by Adaptive Threshold and Sliding Polynomial Fitting","authors":"Kezhao Li, Yunyan Shen, Xiaokui Yue, Yingxiang Jiao, Kai Wang, Zhe Yue, Keke Xu","doi":"10.1155/2023/9421399","DOIUrl":"https://doi.org/10.1155/2023/9421399","url":null,"abstract":"Cycle slip determination plays an important role in high-precision data processing and application of global navigation satellite systems (GNSS). The TurboEdit method consists of the Melbourne-Wubbena (MW) and the geometry-free phase (GF) combination. It can correctly detect and repair cycle slip in most cases. Cycle slip detection (CSD) with GF is disturbed by severe ionospheric delay variations; moreover, CSD or cycle slip repair (CSR) with the MW faces the risk of the disturbance from large pseudorange errors. Hence, cycle slip determination would be difficult under some extreme conditions, e.g., cycle slips occur in low altitude satellite, low sampling rate of dual-frequency observations. To overcome the limitations, a new dual-frequency CSD and CSR method is proposed. The main contents are as follows: (1) compared with the MW method, the Doppler-assisted phase subtraction pseudorange (DAPSP) method that we proposed has no detection blind spot and can effectively reduce the influence of pseudorange noise at high sampling rates; thus, we replace MW by the DAPSP method to improve the detection accuracy. (2) An adaptive threshold model with root mean square (RMS) is established to effectively reduce the missing and false range detection of cycle slip. (3) The sliding polynomial fitting-assisted GF (SPFAGF) is carried out according to the satellite altitude angle. The trend of ionospheric delay and residual multipath effect error between adjacent epochs is extracted and suppressed by SPFAGF. The method combined with DAPSP and SPFAGF (DAPSP-SPFAGF) overcomes the situation that the TurboEdit method cannot effectively detect under extreme conditions. The experimental results of Beidou dual-frequency observation data show that the TurboEdit method and the DAPSP-SPFAGF method can perform CSD and CSR in most cases. At the sampling rate of 1 s, the detection speed of DAPSP-SPFAGF method is significantly faster than TurboEdit method. The number of false positives about CSD is reduced from 68 to 0. At the sampling rate of 30 s and under the condition of the observed satellite altitude angle below 30°, the false alarm rate of the DAPSP-SPFAGF method is 0, but the TurboEdit method’s false alarm rate is 71.2%. So DAPSP-SPFAGF method is prior to the TurboEdit method at the high sampling rates or under extreme conditions, especially it can accurately detect and repair cycle slip and reduce the false positives and false alarm rate.","PeriodicalId":13748,"journal":{"name":"International Journal of Aerospace Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44354615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper highlights the results and comparison of the flow topology investigation above the unmanned combat aerial vehicle (UCAV) configuration, namely, multidisciplinary design configuration (MULDICON), with modified leading-edge profile at the apex region from a sharp to a blunt profile to reduce the complexity of the flow structure above the wing. It was found from the flow visualization results that at a low angle of attack, for instance, 10°, the onset of the flow separation took place near the apex region; the onset of a tip vortex at the wing tip was also detected. At a medium angle of attack, for instance, 15°, the onset of the flow separation moved further upstream with the formation of the apex vortex, and the magnitude of the tip vortex increased due to increasing incoming flow with increasing the angle of attack. At higher angle of attack, for instance, 20°, the apex vortex intensity increased and wing tip vortices shedding is observed. Furthermore, at an angle of attack of 25°, the configuration is partially stalled, while a complete stalled occurred at an angle of attack of 30°. The current results obtained from this study have shown that the configuration has a maximum lift coefficient of 0.8 obtained from the K-Omega-SST turbulence model while it is 0.93 calculated from the Spalart-Allmaras turbulence model, while the maximum drag coefficient is 0.31 and 0.35, respectively, when calculated for the K-Omega-SST turbulence model and the Spalart-Allmaras turbulence model at an AOA of 25°. The flow visualization results revealed that there is a single flow separation due to modified leading edge from sharp to blunt, thus flow complexity is reduced.
{"title":"Experimental and Numerical Study on the Vortical Flow of MULDICON Wing Configuration","authors":"Ibrahim Madan, J. Miau, S. Mat","doi":"10.1155/2023/4045164","DOIUrl":"https://doi.org/10.1155/2023/4045164","url":null,"abstract":"This paper highlights the results and comparison of the flow topology investigation above the unmanned combat aerial vehicle (UCAV) configuration, namely, multidisciplinary design configuration (MULDICON), with modified leading-edge profile at the apex region from a sharp to a blunt profile to reduce the complexity of the flow structure above the wing. It was found from the flow visualization results that at a low angle of attack, for instance, 10°, the onset of the flow separation took place near the apex region; the onset of a tip vortex at the wing tip was also detected. At a medium angle of attack, for instance, 15°, the onset of the flow separation moved further upstream with the formation of the apex vortex, and the magnitude of the tip vortex increased due to increasing incoming flow with increasing the angle of attack. At higher angle of attack, for instance, 20°, the apex vortex intensity increased and wing tip vortices shedding is observed. Furthermore, at an angle of attack of 25°, the configuration is partially stalled, while a complete stalled occurred at an angle of attack of 30°. The current results obtained from this study have shown that the configuration has a maximum lift coefficient of 0.8 obtained from the K-Omega-SST turbulence model while it is 0.93 calculated from the Spalart-Allmaras turbulence model, while the maximum drag coefficient is 0.31 and 0.35, respectively, when calculated for the K-Omega-SST turbulence model and the Spalart-Allmaras turbulence model at an AOA of 25°. The flow visualization results revealed that there is a single flow separation due to modified leading edge from sharp to blunt, thus flow complexity is reduced.","PeriodicalId":13748,"journal":{"name":"International Journal of Aerospace Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-07-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45200208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Corrugated core sandwich structures have great potential in the application to thermal protection system of aerospace vehicles. However, the traditional layout of web plates could inevitably lead to thermal short effects and high risk of buckling failure of the integrated thermal protection system (ITPS). In this paper, a novel double-layer ITPS is proposed by splitting and reorganizing a classical corrugated sandwich structure without additional introducing of weight. Distribution types of parallel, symmetric, and orthogonal of the double layers are designed and studied in detail. Basic theory of the thermomechanical problem as well as finite element simulation is carried out to study the responses of the ITPS. Numerical results show that the orthogonal type has more excellent yield resistance at high temperature and large temperature gradient than the others, while the parallel type has a relatively stronger buckling resistance. In addition, the structural stiffness variation caused by temperature dependencies of material parameters is greater than that caused by thermal stress, which shows the significance of consideration of temperature-dependent material properties in structure vibration analysis.
{"title":"Thermomechanical Behaviors of a Novel Double-Layer Corrugated Core Structure for Thermal Protection System","authors":"Bin Li, Zixuan Hang, Ting Dai","doi":"10.1155/2023/5315977","DOIUrl":"https://doi.org/10.1155/2023/5315977","url":null,"abstract":"Corrugated core sandwich structures have great potential in the application to thermal protection system of aerospace vehicles. However, the traditional layout of web plates could inevitably lead to thermal short effects and high risk of buckling failure of the integrated thermal protection system (ITPS). In this paper, a novel double-layer ITPS is proposed by splitting and reorganizing a classical corrugated sandwich structure without additional introducing of weight. Distribution types of parallel, symmetric, and orthogonal of the double layers are designed and studied in detail. Basic theory of the thermomechanical problem as well as finite element simulation is carried out to study the responses of the ITPS. Numerical results show that the orthogonal type has more excellent yield resistance at high temperature and large temperature gradient than the others, while the parallel type has a relatively stronger buckling resistance. In addition, the structural stiffness variation caused by temperature dependencies of material parameters is greater than that caused by thermal stress, which shows the significance of consideration of temperature-dependent material properties in structure vibration analysis.","PeriodicalId":13748,"journal":{"name":"International Journal of Aerospace Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47027768","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yajuan He, Junli Wang, Jinyang Li, Bofeng Duan, Yang Zhou, Kangjie Wang
In this paper, in order to clarify the influence of structural parameters of laminates on the modal characteristics of high-aspect-ratio wings under prestress, the CFD/CSD coupling method was used to study the modal characteristics of nonlinear structures under the influence of layering angle, layering unbalanced coefficient, and layering reference direction. The results show that the first six order modal frequencies of wing structure increase with the increase of layering angle, and the increment change of frequency increases with the increase of layering angle. The frequency results of positive and negative layering angles are basically the same, and there is no great difference. The modal frequency of airfoil structure is not very sensitive to the change of unbalanced coefficient. The modal frequencies obtained by the mixed angle layering scheme are obviously larger than those obtained by the layering scheme composed of only two angles. With the change of the reference direction of laying, the lowest frequency is generally present in the 0° reference direction and has one or two minima in each order of modal frequency. The layer reference direction angle mainly in the second quadrant is beneficial to the enhancement of modal frequency. After determining the related layer parameters, the appropriate adjustment of the layer reference direction will be beneficial to change the vibration characteristics of the wing structure.
{"title":"Effect of Aeroelastic Tailoring Design on Wing Mode","authors":"Yajuan He, Junli Wang, Jinyang Li, Bofeng Duan, Yang Zhou, Kangjie Wang","doi":"10.1155/2023/1711088","DOIUrl":"https://doi.org/10.1155/2023/1711088","url":null,"abstract":"In this paper, in order to clarify the influence of structural parameters of laminates on the modal characteristics of high-aspect-ratio wings under prestress, the CFD/CSD coupling method was used to study the modal characteristics of nonlinear structures under the influence of layering angle, layering unbalanced coefficient, and layering reference direction. The results show that the first six order modal frequencies of wing structure increase with the increase of layering angle, and the increment change of frequency increases with the increase of layering angle. The frequency results of positive and negative layering angles are basically the same, and there is no great difference. The modal frequency of airfoil structure is not very sensitive to the change of unbalanced coefficient. The modal frequencies obtained by the mixed angle layering scheme are obviously larger than those obtained by the layering scheme composed of only two angles. With the change of the reference direction of laying, the lowest frequency is generally present in the 0° reference direction and has one or two minima in each order of modal frequency. The layer reference direction angle mainly in the second quadrant is beneficial to the enhancement of modal frequency. After determining the related layer parameters, the appropriate adjustment of the layer reference direction will be beneficial to change the vibration characteristics of the wing structure.","PeriodicalId":13748,"journal":{"name":"International Journal of Aerospace Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42889799","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Active rotor control of helicopters is the future development direction, and active flap control (AFC) is one of the most promising technologies. However, the numerical simulation of an AFC rotor is challenging. It is necessary to consider the fidelity of the local flow details while dealing with complex shapes and motions. Therefore, few simulations of the flow field and analyses of the influencing parameters have been conducted. In particular, there is a lack of aerodynamic design criteria and recommendations for the AFC rotor. Thus, a new overset assembly algorithm, an arbitrary multilevel moving grid transformation algorithm, and a solver for the unsteady Reynolds-averaged Navier-Stokes equations (URANS) are proposed to establish a suitable numerical method for AFC rotor simulation. The aerodynamic characteristics of the rotor and key influencing factors are systematically analyzed under different flow conditions and design and control parameters, and suggestions for the design of the AFC rotor are provided. The results show that the AFC significantly changes the load distribution of the rotor. The thrust loss of the rotor is approximately 1%, but the offset angle compensates for the loss. The control parameters show relatively consistent trends under different working conditions. The phase is the key control parameter, and the effect on the load is more pronounced when the control frequency is an integral multiple of the rotor’s natural load frequency. Increasing the chord length, span length, and deflection amplitude can also enhance the active control performance.
{"title":"Parameter Analysis of Active Flap Control for Rotor Aerodynamic Control and Design","authors":"Runze Xia, Zhiyuan Hu, Yongjie Shi, Guohua Xu","doi":"10.1155/2023/8445145","DOIUrl":"https://doi.org/10.1155/2023/8445145","url":null,"abstract":"Active rotor control of helicopters is the future development direction, and active flap control (AFC) is one of the most promising technologies. However, the numerical simulation of an AFC rotor is challenging. It is necessary to consider the fidelity of the local flow details while dealing with complex shapes and motions. Therefore, few simulations of the flow field and analyses of the influencing parameters have been conducted. In particular, there is a lack of aerodynamic design criteria and recommendations for the AFC rotor. Thus, a new overset assembly algorithm, an arbitrary multilevel moving grid transformation algorithm, and a solver for the unsteady Reynolds-averaged Navier-Stokes equations (URANS) are proposed to establish a suitable numerical method for AFC rotor simulation. The aerodynamic characteristics of the rotor and key influencing factors are systematically analyzed under different flow conditions and design and control parameters, and suggestions for the design of the AFC rotor are provided. The results show that the AFC significantly changes the load distribution of the rotor. The thrust loss of the rotor is approximately 1%, but the offset angle compensates for the loss. The control parameters show relatively consistent trends under different working conditions. The phase is the key control parameter, and the effect on the load is more pronounced when the control frequency is an integral multiple of the rotor’s natural load frequency. Increasing the chord length, span length, and deflection amplitude can also enhance the active control performance.","PeriodicalId":13748,"journal":{"name":"International Journal of Aerospace Engineering","volume":" ","pages":""},"PeriodicalIF":1.4,"publicationDate":"2023-06-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41406864","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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