Pub Date : 2024-08-02DOI: 10.1177/09544100241263613
Anukaran Khanna, Bijoy K Mukherjee, Manoranjan Sinha
The present note addresses the novel problem of executing complex aircraft maneuvers under considerable center of gravity (c.g.) uncertainties arising from asymmetrical loading or release of payloads, uneven fuel consumption etc. First, the aircraft flight dynamics under predominantly lateral c.g. movement, is approximated and expressed in a block strict feedback form and thereafter an adaptive backstepping controller is proposed to adapt to the c.g. variations. To alleviate the model uncertainty caused by this model approximation and also to provide robustness to aerodynamic uncertainties in high-alpha regions, a sliding mode control is further integrated with the adaptive backstepping control law. Asymptotic stability conditions of the proposed controller are derived from the first principle using Lyapunov’s method and Barbalat’s lemma. To validate the proposed control scheme, the high-alpha Herbst maneuver is implemented in simulation for the F18-HARV aircraft and the results show that the maneuver performance remains nearly the same under both the nominal and the off-nominal c.g. positions.
{"title":"High-α maneuver under lateral centre of gravity uncertainty: A robust adaptive backstepping control scheme","authors":"Anukaran Khanna, Bijoy K Mukherjee, Manoranjan Sinha","doi":"10.1177/09544100241263613","DOIUrl":"https://doi.org/10.1177/09544100241263613","url":null,"abstract":"The present note addresses the novel problem of executing complex aircraft maneuvers under considerable center of gravity (c.g.) uncertainties arising from asymmetrical loading or release of payloads, uneven fuel consumption etc. First, the aircraft flight dynamics under predominantly lateral c.g. movement, is approximated and expressed in a block strict feedback form and thereafter an adaptive backstepping controller is proposed to adapt to the c.g. variations. To alleviate the model uncertainty caused by this model approximation and also to provide robustness to aerodynamic uncertainties in high-alpha regions, a sliding mode control is further integrated with the adaptive backstepping control law. Asymptotic stability conditions of the proposed controller are derived from the first principle using Lyapunov’s method and Barbalat’s lemma. To validate the proposed control scheme, the high-alpha Herbst maneuver is implemented in simulation for the F18-HARV aircraft and the results show that the maneuver performance remains nearly the same under both the nominal and the off-nominal c.g. positions.","PeriodicalId":54566,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part G-Journal of Aerospace Engineering","volume":"44 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141881199","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}
Pub Date : 2024-07-24DOI: 10.1177/09544100241265639
Yang Guo, Shuai Zhang, Shaobo Wang, Shicheng Wang, Zhiguo Liu
The problem of multi-aircraft cooperative intercepting maneuvering targets is focused in the study. To effectively save the required cost of interception, a cooperative guidance scheme with different roles is considered, and a cooperative guidance method is proposed based on H2 norm performance index under finite-time boundedness conditions. First, a cooperative interception model is established based on the relative motion equation and first-order dynamics characteristics. Second, by considering the system state and finite-time stability characteristics of the output, sufficient conditions for the synthesis of the H2 norm performance of the system under the finite-time bounded conditions are derived. Then, under the finite-time boundedness conditions, a cooperative guidance method with lure roles is designed based on the H2 norm performance index synthesis method. The proposed method can ensure that the defender satisfies the output finite-time convergence characteristic with a small energy consumption. Furthermore, the intermediate state does not exceed the predetermined limit value and effectively saves the overload required for interception during the guidance process. Additionally, simulation experiments are conducted to verify the effectiveness of the proposed method.
{"title":"Defending an interceptor with lure role scenario: A finite-time cooperative guidance method","authors":"Yang Guo, Shuai Zhang, Shaobo Wang, Shicheng Wang, Zhiguo Liu","doi":"10.1177/09544100241265639","DOIUrl":"https://doi.org/10.1177/09544100241265639","url":null,"abstract":"The problem of multi-aircraft cooperative intercepting maneuvering targets is focused in the study. To effectively save the required cost of interception, a cooperative guidance scheme with different roles is considered, and a cooperative guidance method is proposed based on H<jats:sub>2</jats:sub> norm performance index under finite-time boundedness conditions. First, a cooperative interception model is established based on the relative motion equation and first-order dynamics characteristics. Second, by considering the system state and finite-time stability characteristics of the output, sufficient conditions for the synthesis of the H<jats:sub>2</jats:sub> norm performance of the system under the finite-time bounded conditions are derived. Then, under the finite-time boundedness conditions, a cooperative guidance method with lure roles is designed based on the H<jats:sub>2</jats:sub> norm performance index synthesis method. The proposed method can ensure that the defender satisfies the output finite-time convergence characteristic with a small energy consumption. Furthermore, the intermediate state does not exceed the predetermined limit value and effectively saves the overload required for interception during the guidance process. Additionally, simulation experiments are conducted to verify the effectiveness of the proposed method.","PeriodicalId":54566,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part G-Journal of Aerospace Engineering","volume":"31 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141780103","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}
Pub Date : 2024-07-24DOI: 10.1177/09544100241259904
Farshad Heidari, Keyvan Taheri, Maziar Janghorban
Functionally graded materials have been of great interest to researchers for the past two decades. The reason for this is that these materials have outstanding and special material properties compared to many other materials. One of the branches of engineering sciences that has studied these materials in particular during these years is computational mechanics. With this approach, especially static, vibration and buckling analysis, thousands of studies have been done on functionally graded materials. One drawback of these studies is that they are mostly done theoretically and the results of their modeling are not compared with laboratory results although one can find some experimental results in the literature. One reason for not comparing with experimental results could be that these experimental results are buried under tons of theoretical results and do not appear to researchers at all. Our aim in this mini-review is to bring some of these experimental results on functionally graded materials to the showcase for the attention of researchers. The experimental results presented in this article are categorized as follow: a) axially layered FG structure b) axially continuous FG structure c) layered FG structure with variation of properties in the thickness direction d) continuous FG structure with variation of properties in the thickness direction e) FG nanocomposite.
过去二十年来，功能分级材料一直备受研究人员的关注。究其原因，是因为与许多其他材料相比，这些材料具有突出和特殊的材料特性。这些年来，工程科学的一个分支对这些材料进行了特别研究，这就是计算力学。利用这种方法，特别是静态、振动和屈曲分析，已经对功能分级材料进行了数千次研究。这些研究的一个缺点是，它们大多从理论上进行研究，虽然可以在文献中找到一些实验结果，但它们的建模结果并没有与实验室结果进行比较。没有与实验结果进行比较的一个原因可能是，这些实验结果被埋没在大量理论结果之下，根本没有出现在研究人员面前。我们撰写这篇微型综述的目的，就是将这些关于功能梯度材料的实验结果展示出来，引起研究人员的注意。本文介绍的实验结果分为以下几类：a) 轴向分层 FG 结构 b) 轴向连续 FG 结构 c) 在厚度方向上性能变化的分层 FG 结构 d) 在厚度方向上性能变化的连续 FG 结构 e) FG 纳米复合材料。
{"title":"On the experimental results of functionally graded materials with computational mechanics approach: Review","authors":"Farshad Heidari, Keyvan Taheri, Maziar Janghorban","doi":"10.1177/09544100241259904","DOIUrl":"https://doi.org/10.1177/09544100241259904","url":null,"abstract":"Functionally graded materials have been of great interest to researchers for the past two decades. The reason for this is that these materials have outstanding and special material properties compared to many other materials. One of the branches of engineering sciences that has studied these materials in particular during these years is computational mechanics. With this approach, especially static, vibration and buckling analysis, thousands of studies have been done on functionally graded materials. One drawback of these studies is that they are mostly done theoretically and the results of their modeling are not compared with laboratory results although one can find some experimental results in the literature. One reason for not comparing with experimental results could be that these experimental results are buried under tons of theoretical results and do not appear to researchers at all. Our aim in this mini-review is to bring some of these experimental results on functionally graded materials to the showcase for the attention of researchers. The experimental results presented in this article are categorized as follow: a) axially layered FG structure b) axially continuous FG structure c) layered FG structure with variation of properties in the thickness direction d) continuous FG structure with variation of properties in the thickness direction e) FG nanocomposite.","PeriodicalId":54566,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part G-Journal of Aerospace Engineering","volume":"70 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141780104","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}
Pub Date : 2024-07-19DOI: 10.1177/09544100241262554
Yong Wang, Jie Song, Shancheng Li, Haibo Zhang
In order to address the limitation of fixed-ratio transmission (FRT), which compromises the attainment of both optimal main rotor speed and optimal power turbine speed, an optimal speed control method based on hybrid variable speed (HVS) is proposed. Firstly, based on the integrated performance calculation model of helicopter/turboshaft engine system, the distribution factors of variable speed are applied, and the integrated optimization method of optimal speed is proposed based on the minimum engine fuel flow. Subsequently, an online estimation technique employing a high-order filter is devised and engineered to achieve superior cascaded control of turboshaft engines. Finally, a novel real-time optimal speed control method based on hybrid variable speed is proposed. The simulation results under different operation conditions demonstrate that regardless of whether it is FRT or HVS, the optimal main rotor speed increases with forward velocity. In the case of HVS, turboshaft engine degradations have a significant impact on the optimal power turbine speed rather than optimal main rotor speed. Adopting an estimation method based on high-order filtering for gas turbine rotational acceleration proves more advantageous in mitigating high-frequency oscillation and continuous saltation of estimated values. Moreover, in comparison with the optimal speed control method of FRT, HVS-based approach enables simultaneous attainment of the optimal main rotor speed and power turbine speed, thereby enhancing the overall efficiency of the integrated helicopter/turboshaft engine system and significantly decreasing engine fuel consumption by over 2%. Consequently, there has been a remarkable enhancement in the overall performance of the integrated helicopter/turboshaft engine system.
{"title":"Optimal control for helicopter/turboshaft engine system based on hybrid variable speed","authors":"Yong Wang, Jie Song, Shancheng Li, Haibo Zhang","doi":"10.1177/09544100241262554","DOIUrl":"https://doi.org/10.1177/09544100241262554","url":null,"abstract":"In order to address the limitation of fixed-ratio transmission (FRT), which compromises the attainment of both optimal main rotor speed and optimal power turbine speed, an optimal speed control method based on hybrid variable speed (HVS) is proposed. Firstly, based on the integrated performance calculation model of helicopter/turboshaft engine system, the distribution factors of variable speed are applied, and the integrated optimization method of optimal speed is proposed based on the minimum engine fuel flow. Subsequently, an online estimation technique employing a high-order filter is devised and engineered to achieve superior cascaded control of turboshaft engines. Finally, a novel real-time optimal speed control method based on hybrid variable speed is proposed. The simulation results under different operation conditions demonstrate that regardless of whether it is FRT or HVS, the optimal main rotor speed increases with forward velocity. In the case of HVS, turboshaft engine degradations have a significant impact on the optimal power turbine speed rather than optimal main rotor speed. Adopting an estimation method based on high-order filtering for gas turbine rotational acceleration proves more advantageous in mitigating high-frequency oscillation and continuous saltation of estimated values. Moreover, in comparison with the optimal speed control method of FRT, HVS-based approach enables simultaneous attainment of the optimal main rotor speed and power turbine speed, thereby enhancing the overall efficiency of the integrated helicopter/turboshaft engine system and significantly decreasing engine fuel consumption by over 2%. Consequently, there has been a remarkable enhancement in the overall performance of the integrated helicopter/turboshaft engine system.","PeriodicalId":54566,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part G-Journal of Aerospace Engineering","volume":"391 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141738820","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}
Pub Date : 2024-07-18DOI: 10.1177/09544100241264049
Shaoze Li, Jongrae Kim, Andrew Shires
We develop a computational fluid dynamics (CFD) framework to design a feedback circulation control system to compensate for fluctuations in the fixed-wing aircraft caused by wind gusts. Circulation control actions are realized using dynamic boundary conditions in the CFD simulations. The dynamic flow responses with the circulation control are obtained by solving the unsteady Reynolds-averaged Navier-Stokes equations. The dynamic lift responses at several oscillation frequencies of wind gusts and the plenum chamber pressure, which controls the circulation, are also obtained. A system identification algorithm from control theory establishes the transfer functions corresponding to the frequency responses. Based on the transfer functions and the aerodynamic characteristics of circulation control, a feedback circulation control algorithm is designed. The performance of the feedback control system is verified by the CFD simulation coupled with the controller as time-varying boundary conditions. At each time step, the controller determines the parameters in the boundary condition according to the instantaneous lift calculated in the previous time step. The simulation results show that the circulation control effectively compensates for the lift perturbations caused by vertical directional wind gusts. The proposed unsteady CFD simulation frameworks provide high-fidelity evaluations of feedback control systems, and it will save costly efforts to set up unsteady wind-tunnel experiments.
{"title":"Closed-loop computational fluid dynamics simulations with time-varying boundary conditions for circulation control","authors":"Shaoze Li, Jongrae Kim, Andrew Shires","doi":"10.1177/09544100241264049","DOIUrl":"https://doi.org/10.1177/09544100241264049","url":null,"abstract":"We develop a computational fluid dynamics (CFD) framework to design a feedback circulation control system to compensate for fluctuations in the fixed-wing aircraft caused by wind gusts. Circulation control actions are realized using dynamic boundary conditions in the CFD simulations. The dynamic flow responses with the circulation control are obtained by solving the unsteady Reynolds-averaged Navier-Stokes equations. The dynamic lift responses at several oscillation frequencies of wind gusts and the plenum chamber pressure, which controls the circulation, are also obtained. A system identification algorithm from control theory establishes the transfer functions corresponding to the frequency responses. Based on the transfer functions and the aerodynamic characteristics of circulation control, a feedback circulation control algorithm is designed. The performance of the feedback control system is verified by the CFD simulation coupled with the controller as time-varying boundary conditions. At each time step, the controller determines the parameters in the boundary condition according to the instantaneous lift calculated in the previous time step. The simulation results show that the circulation control effectively compensates for the lift perturbations caused by vertical directional wind gusts. The proposed unsteady CFD simulation frameworks provide high-fidelity evaluations of feedback control systems, and it will save costly efforts to set up unsteady wind-tunnel experiments.","PeriodicalId":54566,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part G-Journal of Aerospace Engineering","volume":"82 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141738825","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}
Pub Date : 2024-07-18DOI: 10.1177/09544100241259068
Wei Guo, Qingyong Bian, Chengxiang Zhu, Ning Zhao, Chunling Zhu
Supercooled large droplets (SLDs) under natural icing conditions have the characteristics of easy deformation in motion and easy splashing on impact, and a bimodal droplet size distribution that has received less attention. The modified form of the Rosin-Rammler function was improved to achieve a more accurate nonlinear fitting of the SLD distribution curve. The droplet size distribution was divided into non-equipartition continuous multiple components. The drag source term of each component was coupled with the overall droplet size distribution, and the Eulerian equations of each component of SLDs were solved simultaneously. A new coupled Eulerian method for non-equipartition continuous multi-size droplets was proposed to simulate the impact characteristics of SLDs, and the SLD collection coefficients were validated. Effects of the ratio between the number of large and small droplet components and the number of all components on the simulation results were investigated to select a better combination based on stable convergence calculation steps and the calculation time. This new method was added to the multi-step icing numerical method, and the accuracy and robustness of the method in icing shape prediction were verified based on the freezing drizzle, median volume diameter < 40 μm (FZDZ, MVD < 40 μm) icing condition. Airfoil icing characteristics based on the bimodal and monomodal distribution were compared, and the icing shapes at the leading edge were similar. Still, the upper and lower limits of the icing shapes with the bimodal distribution were nearer to the trailing edge and the ice layer was thicker there.
{"title":"Supercooled large droplet size distribution effects on airfoil icing: A numerical investigation based on a new coupled Eulerian method","authors":"Wei Guo, Qingyong Bian, Chengxiang Zhu, Ning Zhao, Chunling Zhu","doi":"10.1177/09544100241259068","DOIUrl":"https://doi.org/10.1177/09544100241259068","url":null,"abstract":"Supercooled large droplets (SLDs) under natural icing conditions have the characteristics of easy deformation in motion and easy splashing on impact, and a bimodal droplet size distribution that has received less attention. The modified form of the Rosin-Rammler function was improved to achieve a more accurate nonlinear fitting of the SLD distribution curve. The droplet size distribution was divided into non-equipartition continuous multiple components. The drag source term of each component was coupled with the overall droplet size distribution, and the Eulerian equations of each component of SLDs were solved simultaneously. A new coupled Eulerian method for non-equipartition continuous multi-size droplets was proposed to simulate the impact characteristics of SLDs, and the SLD collection coefficients were validated. Effects of the ratio between the number of large and small droplet components and the number of all components on the simulation results were investigated to select a better combination based on stable convergence calculation steps and the calculation time. This new method was added to the multi-step icing numerical method, and the accuracy and robustness of the method in icing shape prediction were verified based on the freezing drizzle, median volume diameter < 40 μm (FZDZ, MVD < 40 μm) icing condition. Airfoil icing characteristics based on the bimodal and monomodal distribution were compared, and the icing shapes at the leading edge were similar. Still, the upper and lower limits of the icing shapes with the bimodal distribution were nearer to the trailing edge and the ice layer was thicker there.","PeriodicalId":54566,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part G-Journal of Aerospace Engineering","volume":"46 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141738821","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}
Pub Date : 2024-07-18DOI: 10.1177/09544100241260109
Lakshmi Srinivas A, Sridhar BTN
Cold flow experiments were conducted on a convergent-divergent (C-D) nozzle with a strut inserted through the nozzle diverging wall to study the internal wall pressure distribution. The objective of the work was to calculate the internal side force and hence the pitching moment generated as a consequence of the side insertion of the strut through the nozzle wall. The generation of side force/pitching moment would be useful for the development of a potential alternative thrust vector control system of flight vehicles employing a supersonic nozzle. The strut was inserted at a distance of 2/3rd of the diverging section length ( L d) of the nozzle from the throat. Two cross sectional shapes of the strut i.e. square with V-notch and semi-ellipse were employed in the experiments. Eight wall pressure ports each on the strut side and on counter strut side of the nozzle axis were used to acquire the pressure data. The design exit Mach number ( M d) corresponding to isentropic flow conditions of the nozzle was 1.84 with an area ratio of 1.48. The cold flow experiments were conducted at three nozzle pressure ratios (NPRs) which were 3.4,5 (both corresponded to over-expansion) and 6.9 (under-expansion). For each strut shape and at a given NPR, strut height ( h s) was varied to study the internal wall pressure distribution. The maximum height of the strut was restricted to the radius of the local cross section of the nozzle (r) where the strut was inserted. From the wall pressure ( p w) distribution, two-dimensional side force ( C s) and moment coefficients ( C m) were calculated. The variation of these coefficients with h s was plotted and the effect of the strut shape for each operational NPR was studied. These variations with h s in respect of square-notch shape and semi elliptical shape were also compared with variations corresponding to square shape available in the literature. The variations of C s and C m were highly nonlinear and trends of both the variations were similar. It was observed from these variations that the semi-elliptical strut shape exhibited a distinct behavior which was in contrast to two other shapes. Variation in h s resulted in both positive and negative values of coefficients in respect of square with V-notch and square shaped struts, whereas in case of semi-elliptical shape mostly positive values of the coefficients were observed. The maximum positive magnitude of C s was observed at strut heights which were 27% and 57% of the local radius of the nozzle cross section (where the strut was inserted) for square with V-notch and semi-elliptical struts respectively.
在汇聚-发散（C-D）喷嘴上进行了冷流实验，在喷嘴发散壁上插入了一根支撑杆，以研究内壁压力分布。这项工作的目的是计算内部侧向力，进而计算因支撑杆侧向插入喷嘴壁而产生的俯仰力矩。侧向力/俯仰力矩的产生有助于开发采用超音速喷嘴的飞行器的潜在替代推力矢量控制系统。支撑杆插入喷嘴喉部的距离是其发散截面长度（L d）的三分之二。实验中使用了两种截面形状的支撑杆，即带 V 形缺口的正方形和半椭圆形。在喷嘴轴线的支杆侧和反支杆侧各使用了八个壁压端口来获取压力数据。喷嘴等熵流条件下的设计出口马赫数（M d）为 1.84，面积比为 1.48。冷流实验在三个喷嘴压力比（NPRs）下进行，分别为 3.4、5（均相当于过度膨胀）和 6.9（膨胀不足）。对于每种支杆形状和给定的 NPR，支杆高度（h s）均有变化，以研究内壁压力分布。支柱的最大高度限制为插入支柱的喷嘴局部横截面半径（r）。根据壁压（p w）分布，计算出二维侧力（C s）和力矩系数（C m）。绘制了这些系数随 h s 的变化曲线，并研究了支柱形状对每种运行 NPR 的影响。这些随 h s 变化的方形缺口形状和半椭圆形形状还与文献中与方形形状相对应的变化进行了比较。C s 和 C m 的变化是高度非线性的，两种变化的趋势相似。从这些变化中可以看出，半椭圆形支杆形状表现出与其他两种形状截然不同的行为。h s 的变化导致带 V 形缺口的方形支柱和方形支柱的系数出现正值和负值，而半椭圆形支柱的系数大多为正值。对于带 V 形缺口的正方形和半椭圆形支柱，在支柱高度分别为喷嘴横截面局部半径（支柱插入处）的 27% 和 57% 时，C s 的正值最大。
{"title":"Role of strut shape on the generation of internal side force and moments in A supersonic nozzle with strut insertion through diverging wall","authors":"Lakshmi Srinivas A, Sridhar BTN","doi":"10.1177/09544100241260109","DOIUrl":"https://doi.org/10.1177/09544100241260109","url":null,"abstract":"Cold flow experiments were conducted on a convergent-divergent (C-D) nozzle with a strut inserted through the nozzle diverging wall to study the internal wall pressure distribution. The objective of the work was to calculate the internal side force and hence the pitching moment generated as a consequence of the side insertion of the strut through the nozzle wall. The generation of side force/pitching moment would be useful for the development of a potential alternative thrust vector control system of flight vehicles employing a supersonic nozzle. The strut was inserted at a distance of 2/3<jats:sup>rd</jats:sup> of the diverging section length ( L<jats:sub> d</jats:sub>) of the nozzle from the throat. Two cross sectional shapes of the strut i.e. square with V-notch and semi-ellipse were employed in the experiments. Eight wall pressure ports each on the strut side and on counter strut side of the nozzle axis were used to acquire the pressure data. The design exit Mach number ( M<jats:sub> d</jats:sub>) corresponding to isentropic flow conditions of the nozzle was 1.84 with an area ratio of 1.48. The cold flow experiments were conducted at three nozzle pressure ratios (NPRs) which were 3.4,5 (both corresponded to over-expansion) and 6.9 (under-expansion). For each strut shape and at a given NPR, strut height ( h<jats:sub> s</jats:sub>) was varied to study the internal wall pressure distribution. The maximum height of the strut was restricted to the radius of the local cross section of the nozzle (r) where the strut was inserted. From the wall pressure ( p<jats:sub> w</jats:sub>) distribution, two-dimensional side force ( C<jats:sub> s</jats:sub>) and moment coefficients ( C<jats:sub> m</jats:sub>) were calculated. The variation of these coefficients with h<jats:sub> s</jats:sub> was plotted and the effect of the strut shape for each operational NPR was studied. These variations with h<jats:sub> s</jats:sub> in respect of square-notch shape and semi elliptical shape were also compared with variations corresponding to square shape available in the literature. The variations of C<jats:sub> s</jats:sub> and C<jats:sub> m</jats:sub> were highly nonlinear and trends of both the variations were similar. It was observed from these variations that the semi-elliptical strut shape exhibited a distinct behavior which was in contrast to two other shapes. Variation in h<jats:sub> s</jats:sub> resulted in both positive and negative values of coefficients in respect of square with V-notch and square shaped struts, whereas in case of semi-elliptical shape mostly positive values of the coefficients were observed. The maximum positive magnitude of C<jats:sub> s</jats:sub> was observed at strut heights which were 27% and 57% of the local radius of the nozzle cross section (where the strut was inserted) for square with V-notch and semi-elliptical struts respectively.","PeriodicalId":54566,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part G-Journal of Aerospace Engineering","volume":"53 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-07-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141738824","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}
Pub Date : 2024-06-25DOI: 10.1177/09544100241262689
Tianpeng Huang, Junxiao Ren, Liang Li, Huishuang Shao, Tao Yu
Attitude stability plays an important role in quadrotor aircraft. However, it is difficult to design a robust controller to precisely track a desired attitude trajectory in the presence of external disturbance. To address this problem, a nonlinear disturbance estimator with finite-time convergence is proposed to estimate external disturbance. Then, a dynamic surface control scheme based on the disturbance estimator is developed. Therefore, the compensation for external disturbance can be achieved in the designed controller. Furthermore, the L ∞ performance of transient attitude tracking error is achieved by analyzing solution of Lyapunov function. The finite-time convergence of disturbance estimation error and the asymptotical convergence of attitude tracking error of closed-loop system are rigorously proved. Finally, the numerical simulations are carried out to demonstrate the effectiveness of the developed disturbance estimator and control scheme.
姿态稳定性在四旋翼飞行器中发挥着重要作用。然而，在存在外部干扰的情况下，很难设计出一种鲁棒控制器来精确跟踪所需的姿态轨迹。为了解决这个问题，我们提出了一种具有有限时间收敛性的非线性扰动估计器来估计外部扰动。然后，开发了一种基于扰动估计器的动态表面控制方案。因此，所设计的控制器可以实现对外部扰动的补偿。此外，通过分析 Lyapunov 函数的解，实现了瞬态姿态跟踪误差的 L ∞ 性能。严格证明了扰动估计误差的有限时间收敛性和闭环系统姿态跟踪误差的渐近收敛性。最后，还进行了数值模拟，以证明所开发的扰动估计器和控制方案的有效性。
{"title":"Robust attitude trajectory tracking control for a quadrotor under external disturbance","authors":"Tianpeng Huang, Junxiao Ren, Liang Li, Huishuang Shao, Tao Yu","doi":"10.1177/09544100241262689","DOIUrl":"https://doi.org/10.1177/09544100241262689","url":null,"abstract":"Attitude stability plays an important role in quadrotor aircraft. However, it is difficult to design a robust controller to precisely track a desired attitude trajectory in the presence of external disturbance. To address this problem, a nonlinear disturbance estimator with finite-time convergence is proposed to estimate external disturbance. Then, a dynamic surface control scheme based on the disturbance estimator is developed. Therefore, the compensation for external disturbance can be achieved in the designed controller. Furthermore, the L<jats:sub> ∞</jats:sub> performance of transient attitude tracking error is achieved by analyzing solution of Lyapunov function. The finite-time convergence of disturbance estimation error and the asymptotical convergence of attitude tracking error of closed-loop system are rigorously proved. Finally, the numerical simulations are carried out to demonstrate the effectiveness of the developed disturbance estimator and control scheme.","PeriodicalId":54566,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part G-Journal of Aerospace Engineering","volume":"46 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141505851","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}
Pub Date : 2024-06-24DOI: 10.1177/09544100241263896
Guangwei Wu, Ziao Wang, Fuxu Quan, Juntao Chang
To solve the problem that the control of shock wave elimination is weakened under off-design conditions, the design concept of a variable-geometry inlet scheme that combines the variable-geometry cowl (translating and diagonalizing) with regulating shock wave elimination is introduced in this paper. The variable-geometry inlet is designed by the theories of oblique shock wave and isentropic wave as well as the Oswatitsch theory. Regulatory law of the variable-geometry cowl based on shock wave elimination is obtained by the geometric relationships between cowl compression angle, cowl shock wave angle, and optimal control point or range. Numerical simulations are conducted to investigate flow field characteristics, control mechanism, and working performance of the inlet. Results reveal that expansion waves have a significant impact on the cowl shock wave and boundary layer interaction, and flow separation. Furthermore, variable-geometry inlet with translating and diagonalizing cowl based on the regulation of shock wave elimination effectively controls and even completely eliminates the flow separation. In terms of inlet performance, the total pressure loss of the variable-geometry inlet decreases such that the total pressure recovery coefficients of the translating cowl and diagonalizing cowl inlets are increased by maximum values of 3.39 % and 9.97 %, respectively. However, the mass flow coefficient of translating cowl inlet decreases, whereas that of the diagonalizing cowl inlet is equivalent to that of the fixed-geometry inlet. The working range can be widened by changing the internal contract ratio of the inlet through translating or diagonalizing the cowl. The results confirm that the scheme of variable geometry inlet with diagonalizing cowl is practicable and reliable and has important guiding significance and value for inlet design.
{"title":"Design and aerodynamic characteristics of variable-geometry hypersonic inlet based on shock wave elimination","authors":"Guangwei Wu, Ziao Wang, Fuxu Quan, Juntao Chang","doi":"10.1177/09544100241263896","DOIUrl":"https://doi.org/10.1177/09544100241263896","url":null,"abstract":"To solve the problem that the control of shock wave elimination is weakened under off-design conditions, the design concept of a variable-geometry inlet scheme that combines the variable-geometry cowl (translating and diagonalizing) with regulating shock wave elimination is introduced in this paper. The variable-geometry inlet is designed by the theories of oblique shock wave and isentropic wave as well as the Oswatitsch theory. Regulatory law of the variable-geometry cowl based on shock wave elimination is obtained by the geometric relationships between cowl compression angle, cowl shock wave angle, and optimal control point or range. Numerical simulations are conducted to investigate flow field characteristics, control mechanism, and working performance of the inlet. Results reveal that expansion waves have a significant impact on the cowl shock wave and boundary layer interaction, and flow separation. Furthermore, variable-geometry inlet with translating and diagonalizing cowl based on the regulation of shock wave elimination effectively controls and even completely eliminates the flow separation. In terms of inlet performance, the total pressure loss of the variable-geometry inlet decreases such that the total pressure recovery coefficients of the translating cowl and diagonalizing cowl inlets are increased by maximum values of 3.39 % and 9.97 %, respectively. However, the mass flow coefficient of translating cowl inlet decreases, whereas that of the diagonalizing cowl inlet is equivalent to that of the fixed-geometry inlet. The working range can be widened by changing the internal contract ratio of the inlet through translating or diagonalizing the cowl. The results confirm that the scheme of variable geometry inlet with diagonalizing cowl is practicable and reliable and has important guiding significance and value for inlet design.","PeriodicalId":54566,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part G-Journal of Aerospace Engineering","volume":"82 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141505849","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}
Continuum robots are flexible and compliant. Compared to the case in conventional articulated manipulators, the driving unit can be placed outside the workspace of the robot, so that the motion orientation has a relatively complete linear configuration flow, which can be applied to a special environment with narrow and multiple obstacles such as aerospace. This study presents the development process of a tendon-driven continuum robot (TCR) with a high length-diameter ratio. The skeleton structure which imitates a snake is composed of continuous joints in series. The driving device is operated by using a tendon-driven method, which reduces the complexity of the driving box and control system significantly. The diameter of the robot is designed to be 5 mm, which enables it to work in a narrow and slender space with certain flexibility. Subsequently, a kinematic model of the robot is established. The mode function backbone method is applied to realize TCR trajectory planning. An idea of segmented solving is adopted to achieve trajectory tracking control of the continuum robot. Finally, a prototype of the continuum robot is produced, and the rationality of the robot design and the effectiveness of the motion control method are verified through trajectory simulations and experiments. The robot can perform inspection tasks within a narrow gap of 20 mm with good environmental adaptability.
{"title":"Design and motion control of a tendon-driven continuum robot for aerospace applications","authors":"Qian Qi, Guodong Qin, Zhikang Yang, Guangming Chen, Jiajun Xu, Zhuhai Lv, Aihong Ji","doi":"10.1177/09544100241263004","DOIUrl":"https://doi.org/10.1177/09544100241263004","url":null,"abstract":"Continuum robots are flexible and compliant. Compared to the case in conventional articulated manipulators, the driving unit can be placed outside the workspace of the robot, so that the motion orientation has a relatively complete linear configuration flow, which can be applied to a special environment with narrow and multiple obstacles such as aerospace. This study presents the development process of a tendon-driven continuum robot (TCR) with a high length-diameter ratio. The skeleton structure which imitates a snake is composed of continuous joints in series. The driving device is operated by using a tendon-driven method, which reduces the complexity of the driving box and control system significantly. The diameter of the robot is designed to be 5 mm, which enables it to work in a narrow and slender space with certain flexibility. Subsequently, a kinematic model of the robot is established. The mode function backbone method is applied to realize TCR trajectory planning. An idea of segmented solving is adopted to achieve trajectory tracking control of the continuum robot. Finally, a prototype of the continuum robot is produced, and the rationality of the robot design and the effectiveness of the motion control method are verified through trajectory simulations and experiments. The robot can perform inspection tasks within a narrow gap of 20 mm with good environmental adaptability.","PeriodicalId":54566,"journal":{"name":"Proceedings of the Institution of Mechanical Engineers Part G-Journal of Aerospace Engineering","volume":"168 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-06-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141505852","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：