Journal of the American Helicopter Society最新文献_第5页

A Novel Modeling Strategy for the Dynamical Analysis of Coupled Coaxial Rotors/Auxiliary Propeller/Drive Train System 一种新的同轴转子/辅助螺旋桨/传动系耦合系统动力学分析建模策略

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.68.012003

Xiao Wang, Laishou Song, P. Xia

{"title":"A Novel Modeling Strategy for the Dynamical Analysis of Coupled Coaxial Rotors/Auxiliary Propeller/Drive Train System","authors":"Xiao Wang, Laishou Song, P. Xia","doi":"10.4050/jahs.68.012003","DOIUrl":"https://doi.org/10.4050/jahs.68.012003","url":null,"abstract":"The coupled coaxial rotors/auxiliary propeller/drive train system of a compound helicopter may exhibit torsional instability. A novel modeling strategy based on the transfer matrix method is developed and used to analyze the coupled torsional system. In contrast to the finite element method, the proposed modeling strategy offers more elegant formulations of the dynamic equations for the rigid-flexible multibody system. The highlight includes the overall transfer equation that can be directly obtained according to the topology figure of the system by introducing a virtual branch element to decouple the tree topology system as a combination of the chain systems. Besides, another virtual connection element is introduced to deal with the state vector dimension mismatch problem, improving the computational efficiency by further reducing the scale of the overall transfer matrix. A new transfer matrix of a rotor blade for lead–lag motion is derived. The influences of different flight conditions on torsional vibration are highlighted. And several suggestions on torsional vibration design are concluded.","PeriodicalId":50017,"journal":{"name":"Journal of the American Helicopter Society","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70218402","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}

引用次数: 0

Computational Characterization of Unsteadiness and Turbulence in Rotor Hub Wakes 旋翼轮毂尾迹非定常与湍流的计算表征

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.68.012007

Forrest Mobley, Tristan D. Wall, J. Coder

引用次数: 0

System and Component Level Design Procedure for High Reduction Ratio Pericyclic Drive 大减速比周圈传动系统及部件级设计程序

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.67.032003

Tanmay D. Mathur, E. Smith, H. Desmidt, R. Bill

引用次数: 0

Analysis of Large-Scale Hybrid Aerospace Spur Gear Drivetrains 大型混合动力航空直齿轮传动系统分析

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.68.012004

Sean Gauntt, S. McIntyre, R. Campbell

{"title":"Analysis of Large-Scale Hybrid Aerospace Spur Gear Drivetrains","authors":"Sean Gauntt, S. McIntyre, R. Campbell","doi":"10.4050/jahs.68.012004","DOIUrl":"https://doi.org/10.4050/jahs.68.012004","url":null,"abstract":"The hybrid gear concept, which combines a metallic outer rim of gear teeth with a composite web, has shown potential to reduce the weight of small-scale spur gears without negatively affecting vibration performance for low- and medium-speed applications. In this paper, the hybrid gear design and tooth microgeometry optimization technique that had been applied to small-scale spur gears was adapted for application to spur gears of aerospace-relevant scale, speed, and load. A single reduction drivetrain model was developed featuring large-scale hybrid spur gears, which was used to determine optimal tooth microgeometry modifications that minimized peak-to-peak transmission error. Static and dynamic transmission error analyses were then performed using the optimal microgeometries. Results were compared to those predicted for a similarly-optimized all-steel drivetrain. The application of optimal tooth microgeometries to large-scale hybrid gears led to a more significant decrease in a peak-to-peak transmission error than was observed for the small-scale gears. Similar to results for small-scale hybrid gears, the drivetrains featuring large-scale hybrid gears predicted similar dynamic transmission errors to their all-steel counterparts at low and medium speeds, while significantly different transmission errors were predicted at high speeds.","PeriodicalId":50017,"journal":{"name":"Journal of the American Helicopter Society","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70218465","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}

引用次数: 0

Variations in Thrust Sharing for Torque-Balanced Lift-Offset Coaxial Rotors 转矩平衡升力偏置同轴转子的推力分担变化

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.68.022008

J. Ho, H. Yeo

引用次数: 0

A New Heuristic Approach to Rotorcraft System Identification 一种新的启发式旋翼机系统辨识方法

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.68.022005

Linghai Lu, Dheeraj Agarwal, G. Padfield, M. White, N. Cameron

{"title":"A New Heuristic Approach to Rotorcraft System Identification","authors":"Linghai Lu, Dheeraj Agarwal, G. Padfield, M. White, N. Cameron","doi":"10.4050/jahs.68.022005","DOIUrl":"https://doi.org/10.4050/jahs.68.022005","url":null,"abstract":"High-fidelity rotorcraft flight simulation relies on the availability of a quality flight model that further demands a good level of understanding of the complexities arising from aerodynamic couplings and interference effects. This paper explores rotorcraft flight dynamics in the low-speed regime where such complexities abound and presents a new heuristic approach in the time domain to aid identification of nonlinear dynamics and fidelity assessment. The approach identifies flight model parameters “additively,” based on their contribution to the local dynamic response of the system, in contrast with conventional approaches where parameter values are identified to minimize errors over a whole maneuver. In these early investigations, identified low-order, rigid-body, linear models show good comparison with flight-test data. The approach is extended to explore nonlinearities attributed to the so-called maneuver wake distortion and wake skew effects emerging in larger maneuvers. The results show a good correlation for the proposed nonlinear model structure, demonstrated by its capability to capture the time response and variations of the stability and control derivatives with response magnitude.","PeriodicalId":50017,"journal":{"name":"Journal of the American Helicopter Society","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70219102","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}

引用次数: 0

Exploration on Nonaxisymmetric Flow Phenomenon in a Slinger Injector 斜杆喷射器非轴对称流动现象的探讨

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.67.032011

Fang Wang, Yu-Dong Wang, Xiang Gao, Yulin Ye, Rui Liu, Han Gao, Jie Jin

{"title":"Exploration on Nonaxisymmetric Flow Phenomenon in a Slinger Injector","authors":"Fang Wang, Yu-Dong Wang, Xiang Gao, Yulin Ye, Rui Liu, Han Gao, Jie Jin","doi":"10.4050/jahs.67.032011","DOIUrl":"https://doi.org/10.4050/jahs.67.032011","url":null,"abstract":"The slinger is an important configuration of an aeroengine combustion chamber. It is well matched to smaller gas turbines that are more sensitive to cost than larger and more sophisticated models. The slinger combustor is inherently low cost itself, by eliminating fuel injectors and much of the fuel tubing and manifolding and also reducing costs in the requirements of the main fuel pump by operating at fuel delta pressures significantly lower than conventional fuel systems. The slinger's inherent drawbacks of increased combustion liner surface area and less atomization are less of a concern in a lower temperature, lower cost small turbines. The slinger's internal flow is of great significance to fuel atomization. This paper conducts experiments and numerical simulations on the slinger fuel injector. Numerical analysis and high-speed photography of the fuel slinger were applied to investigate the film flow pattern inside the slinger and the liquid phase distribution inside the combustion chamber to predict the flow field in an aeroengine combustion chamber. The transient Reynolds-averaged Navier–Stokes method, the volume of fluid method, and the discrete phase method were adopted in the simulation, and a high-speed camera and the rotational rig were used to perform the experiments. The nonaxisymmetric flow was present in the slinger and the combustor space. In the simulation results, the total mass-flow rate varies with time. Each hole's mass-flow rate value in the slinger is also different at the same time. The Sauter mean diameter (SMD) difference for each injection orifice is relatively small compared with the SMD difference caused by a rotation rate. The spatial distribution of the spray is also uneven as shown in the result of different single discharge channels' mass-flow rates. The experimental photos confirmed the simulation outcomes. The general theoretical analysis was made that these nonaxisymmetric phenomena were driven by the combined action of centrifugal force, surface tension, and instability phenomenon.","PeriodicalId":50017,"journal":{"name":"Journal of the American Helicopter Society","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70217773","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}

引用次数: 0

Design Optimization of a Hybrid Spur Gear Including Tooth Bending Effects 含齿弯效应的混合直齿齿轮设计优化

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.67.042009

Sean Gauntt, Sean Mcintyre, R. Campbell

引用次数: 0

Understanding Upward Scalability of Cycloidal Rotors for Large-Scale UAS Applications 了解大规模无人机应用中摆线转子的向上可扩展性

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.67.042002

Atanu Halder, Moble Benedict

{"title":"Understanding Upward Scalability of Cycloidal Rotors for Large-Scale UAS Applications","authors":"Atanu Halder, Moble Benedict","doi":"10.4050/jahs.67.042002","DOIUrl":"https://doi.org/10.4050/jahs.67.042002","url":null,"abstract":"This paper investigates the upward scalability of a cycloidal rotor (also known as a cyclorotor) from an aeromechanics standpoint while utilizing a two-dimensional computational fluid dynamics (CFD) solver and a lower order aeroelastic model. The CFD results show that the nondimensional thrust remains almost unchanged with increasing Reynolds number, while the nondimensional torque and power decrease significantly from Re=104 to 105, which clearly shows that the cycloidal rotor scales up favorably from thrust production and aerodynamic efficiency standpoints. The structural scalability study shows that as the cyclorotor size is increased, the blade weight per unit thrust remains constant; however, the blade stress increases monotonically if the rotor geometry is kept similar. This monotonic increase in the blade stress is found to be independent of the blade structural design. To bound the blade stress with increasing size, the diameter of the cyclorotor needs to be increased at a faster rate compared to the blade span, which reduces the rotor aspect ratio (blade-span/rotor-diameter). Proper scaling laws necessary to bound the blade stress are formulated. Utilizing these insights, an optimization framework based on a genetic algorithm is developed to determine optimal cyclorotor configurations for a thrust range from 1 to 1000 lb.","PeriodicalId":50017,"journal":{"name":"Journal of the American Helicopter Society","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70218261","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}

引用次数: 1

Hover Handling Qualities of Fixed-Pitch, Variable-RPM Quadcopters of Increasing Size 尺寸不断增大的定距变转速四轴飞行器的悬停操纵特性

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.67.042010

Ariel Walter, M. McKay, R. Niemiec, F. Gandhi, Christina M. Ivler

{"title":"Hover Handling Qualities of Fixed-Pitch, Variable-RPM Quadcopters of Increasing Size","authors":"Ariel Walter, M. McKay, R. Niemiec, F. Gandhi, Christina M. Ivler","doi":"10.4050/jahs.67.042010","DOIUrl":"https://doi.org/10.4050/jahs.67.042010","url":null,"abstract":"Fixed-pitch, variable-RPM quadcopters of increasing size are simulated in hover. Three aircraft sizes are considered, with rotor diameters of 4, 6, and 8 ft (1.2, 1.8, and 2.4 m) and gross weights of 300, 680, and 1200 lb (136, 308, and 544 kg) respectively. Control design is performed for each aircraft using CONDUIT®, first using standard ADS-33E-PRF handling qualities specifications. Froude scaling is then applied to the specifications in order to design more comparable, aggressive controllers for the two smaller aircraft. Piloted commands and gust inputs are simulated in the time domain in order to estimate the necessary motor current margins needed for adequate maneuverability local to hover. Of the maneuvers considered, a yaw rate step requires the highest current margin for the smallest aircraft, while the longitudinal velocity step requires the highest current margin for the others, regardless of the Froude scaling of the handling qualities metrics. Using the maximum current values from these simulations, the motor weight fraction is 8.3–10.6% for the 300-lb vehicle, 11.6–13.0% for the 680-lb vehicle, and 15.8% for the 1200 lb. Motor weight requirements can be reduced on the larger two aircraft by flying with the pitch and roll axes exclusively in the attitude command, attitude hold mode, rather than translational rate command. In this case, step commands in yaw rate are limiting for the 680-lb vehicle (10.7–11.8% motor weight fraction) and heave commands are limiting for the 1200-lb vehicle (13.6% motor weight fraction). Estimated motor weight requirements are also reduced by decreasing the rotor inertia and introducing additional filtering into the aircraft commands.","PeriodicalId":50017,"journal":{"name":"Journal of the American Helicopter Society","volume":"1 1","pages":""},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70218337","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}

引用次数: 1