Journal of the American Helicopter Society最新文献_第7页

Full-Scale Reynolds Number Testing of Rotor Hub Drag and Wake Turbulence 旋翼轮毂阻力和尾流湍流的全尺寸雷诺数测试

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.67.042008

D. Reich, M. Krane, S. Willits, S. Schmitz

引用次数: 1

Leading-Edge Suction Behavior of Unsteady Airfoils in Forward and Reverse Flows 非定常翼型在正反流中的前缘吸力特性

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.68.022009

S. Narsipur, Ashok Gopalarathnam

{"title":"Leading-Edge Suction Behavior of Unsteady Airfoils in Forward and Reverse Flows","authors":"S. Narsipur, Ashok Gopalarathnam","doi":"10.4050/jahs.68.022009","DOIUrl":"https://doi.org/10.4050/jahs.68.022009","url":null,"abstract":"To model unsteady airfoil aerodynamics in forward and reverse flows in a simple and robust manner requires a strong understanding of the complex flow dynamics and their relation to first-order concepts. The current work explores the relation between the leading-edge suction force, represented nondimensionally by the leading-edge suction parameter (LESP), and the flow physics of forward and reverse dynamic stall as a function of freestream Reynolds number, airfoil thickness, and motion kinematics for the NACA 0012, 0015, and 0018 airfoils using computational tools. The relation between the LESP and critical events associated with leading-edge vortex (LEV) shedding was found to be independent of flow direction barring the signature to identify LEV initiation. Leading-edge suction was observed to continue to increase after LEV initiation in reverse flow and could be attributed to the combined effect of a weak LEV and strong trailing-edge vortice. While LESP, forces, and moments were found to be moderately dependent on airfoil thickness and strongly dependent on the Reynolds number in forward flow conditions and the critical LESP, in addition, was weakly dependent on motion kinematics, the aerodynamics were observed to be largely independent of said parameters in reverse flow. This allows for a single critical LESP value to be used for symmetric airfoils to indicate LEV initiation when the blunt edge is experiencing reversed flow, a finding which serves to largely reduce the empirical dependencies while modeling unsteady reverse dynamic stall in low-order methods.","PeriodicalId":50017,"journal":{"name":"Journal of the American Helicopter Society","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70218914","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

Control Allocation Reconfiguration for Actuator Failure on a Coaxial-Pusher Helicopter 同轴推进直升机作动器故障控制分配重构

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.68.032004

M. McKay, Praneet Vayalali, F. Gandhi, T. Berger, Mark J. S. Lopez

引用次数: 0

Interactional Aerodynamics of the XV-15 Tiltrotor Aircraft during Conversion Maneuvers XV-15倾转旋翼机在转换机动过程中的相互作用空气动力学

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.67.032005

S. Tran, Joon W. Lim

{"title":"Interactional Aerodynamics of the XV-15 Tiltrotor Aircraft during Conversion Maneuvers","authors":"S. Tran, Joon W. Lim","doi":"10.4050/jahs.67.032005","DOIUrl":"https://doi.org/10.4050/jahs.67.032005","url":null,"abstract":"The high-fidelity computational fluid dynamics (CFD) tool CREATE™-AV HELIOS is used to investigate the interactional aerodynamics of the XV-15 tiltrotor in this work. The full vehicle is studied in a quasi-static manner with various airspeeds, nacelle angles, and vehicle attitudes to simulate hover-to-forward flight transition. The rotor is trimmed using CFD/CSD coupling with CAMRAD II. Significant wing-on-rotor interactions are observed where the thickness and loading effects of the wing create an impulsive doublet loading on the rotor as it passes over the wings. Furthermore, the wing is shown to alter the blade–vortex interactions of the rotor at high nacelle angles. The rotor in turn noticeably alters the lift and drag characteristics of the wing. At moderate to low nacelle angles, the rotor downwash enhances the dynamic pressure primarily on the upper surface of the wing, increasing the total wing lift by up to 14%. The effect on the drag varies depending on the nacelle angle. At high nacelle angles, the rotor is shown to decrease both lift and drag of the wing by 15% and 20%, respectively. Overall, this work serves to illuminate and quantify some of the complex aerodynamic interactions that occur during the conversion maneuver of tiltrotor aircraft.","PeriodicalId":50017,"journal":{"name":"Journal of the American Helicopter Society","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70217236","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

A Dimensionality Reduction Approach in Helicopter Hover Performance Flight Testing 直升机悬停性能飞行试验中的降维方法

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.67.032010

I. Arush, M. Pavel, M. Mulder

引用次数: 1

Linear Time-Invariant Approximations of Nonlinear Time-Periodic Systems 非线性时间周期系统的线性时不变逼近

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.68.012006

Umberto Saetti, J. Horn

{"title":"Linear Time-Invariant Approximations of Nonlinear Time-Periodic Systems","authors":"Umberto Saetti, J. Horn","doi":"10.4050/jahs.68.012006","DOIUrl":"https://doi.org/10.4050/jahs.68.012006","url":null,"abstract":"This paper discusses the development of a numerical method for the approximation of the nonlinear time-periodic rotorcraft flight dynamics with higher order linear time-invariant (LTI) models. The method relies on a per-rotor revolution perturbation scheme, which is of particular importance for the linearization of simulation models that do not allow for per-time-step perturbations, and for those output measures that necessitate the solution of partial differential equations and thus require several time steps to be computed. The paper demonstrates the application of the proposed methodology to obtain high-order LTI models capable of predicting vibrations for a generic utility helicopter. Simulations are used to validate the response of the linearized models against those from nonlinear simulations and from competing approaches in the literature. The proposed method is shown to predict accurately the nonlinear response for the case shown and for small amplitude maneuvers. Frequency-domain validation is also performed to compare the linear models derived with the proposed method with those obtained with harmonic decomposition, a competing approach based on a per-time-step perturbation scheme. Interestingly, the proposed algorithm yields nearly identical numerical results compared to harmonic decomposition, suggesting that the two methods are in fact equivalent but rely on different formulations.","PeriodicalId":50017,"journal":{"name":"Journal of the American Helicopter Society","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70218756","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

Acoustic Analysis and Sound Quality Assessment of a Quiet Helicopter for Air Taxi Operations 一种用于空中滑行的静音直升机的声学分析和音质评估

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.67.032001

Sicheng Li, Seongkyu Lee

{"title":"Acoustic Analysis and Sound Quality Assessment of a Quiet Helicopter for Air Taxi Operations","authors":"Sicheng Li, Seongkyu Lee","doi":"10.4050/jahs.67.032001","DOIUrl":"https://doi.org/10.4050/jahs.67.032001","url":null,"abstract":"This paper investigates tonal and broadband noise for rotor designs used on urban air mobility vehicles. Quiet helicopter rotor designs with varying tip speeds and blade numbers are studied for the tonal and broadband noise at the same mission specification. The rotor aerodynamics in edge-wise forward flight are calculated using the blade element theory coupled with a dynamic inflow model and the moment-balance trim analysis. Loading noise and thickness noise are obtained using the lifting-line loading distribution and the dual-compact thickness noise model in PSU-WOPWOP. With the forward flight capability developed in UCD-QuietFly, broadband noise, including trailing-edge noise, trailing-edge bluntness noise, and airfoil stall noise, is predicted. Psychoacoustic metrics, such as fluctuation and roughness, are used to quantify the human subjective annoyance levels. The relative importance between tonal noise and broadband noise is investigated for various design cases and operating conditions. It is found that broadband noise is the dominant noise source for the rotor designs with low tip speeds and fewer blades, while tonal noise is dominant for the high-tip-speed designs. A low tip speed and more blades are found to be the preferable design features in terms of psychoacoustic metrics.","PeriodicalId":50017,"journal":{"name":"Journal of the American Helicopter Society","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70217264","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: 10

Further Development and Piloted Simulation Evaluation of the Break Turn ADS-33 Mission Task Element 破弯ADS-33任务单元的进一步开发与试验仿真评估

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.67.042003

H. Xin, J. Horn, Roy Brewer, D. Klyde, Cody E. Fegely, Paul Ruckel, Frank Conway, Sean P. Pitoniak, William C. Fell, J. Rigsby, R. Mulato, P. Schulze, Carl Ott, C. Blanken

{"title":"Further Development and Piloted Simulation Evaluation of the Break Turn ADS-33 Mission Task Element","authors":"H. Xin, J. Horn, Roy Brewer, D. Klyde, Cody E. Fegely, Paul Ruckel, Frank Conway, Sean P. Pitoniak, William C. Fell, J. Rigsby, R. Mulato, P. Schulze, Carl Ott, C. Blanken","doi":"10.4050/jahs.67.042003","DOIUrl":"https://doi.org/10.4050/jahs.67.042003","url":null,"abstract":"Cofunded by the U.S. Army and industry, a Sikorsky-led team that features industry and academia developed and evaluated a set of mission task elements (MTE) to address rotorcraft high-speed handling qualities. The MTEs were designed to meet different levels of precision and aggressiveness. The Break Turn MTE was defined for nonprecision, aggressive applications. The MTE objectives, descriptions, and performance criteria were developed via piloted simulation sessions at each team's simulator, each featuring a unique high-speed platform including a coaxial compound helicopter, two tiltrotors, and a generic winged compound helicopter. Formal evaluations were conducted by U.S. Army test pilots. Baseline control laws were varied to achieve different handling qualities levels. Quantitative measures based on task performance and qualitative measures based on pilot ratings, comments, and questionnaires were used to assess MTE effectiveness. It was demonstrated that the Break Turn MTE provided an effective means to discern nonprecision, aggressive handling qualities in high-speed flight.","PeriodicalId":50017,"journal":{"name":"Journal of the American Helicopter Society","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70218362","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: 4

Visual and Control Augmentation Techniques for Pilot Assistance During Helicopter Shipboard Recovery 直升机舰载回收过程中辅助飞行员的视觉和控制增强技术

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.67.042004

T. Mehling, Omkar Halbe, M. Hajek, M. Vrdoljak

{"title":"Visual and Control Augmentation Techniques for Pilot Assistance During Helicopter Shipboard Recovery","authors":"T. Mehling, Omkar Halbe, M. Hajek, M. Vrdoljak","doi":"10.4050/jahs.67.042004","DOIUrl":"https://doi.org/10.4050/jahs.67.042004","url":null,"abstract":"Shipboard launch and recovery of helicopters continue to pose operational challenges even to experienced pilots. The present research seeks to develop novel visual and control augmentation techniques and determine their impact on human factors for shipboard recovery operations. The paper first outlines the development and integration of a helicopter–ship dynamic interface model into a wide field of view, fixed-base rotorcraft simulation environment. The paper then describes the development of novel visual and control augmentation techniques for pilot assistance during shipboard recovery. Visual augmentation includes two-dimensional primary flight information and three-dimensional conformal shipboard landing symbology presented on a low-cost, off-the-shelf, see-through head-mounted display system to facilitate “eyes-out” piloting. Control augmentation includes robust nonlinear control laws producing translational rate command position hold, and acceleration command velocity hold response types with good predicted handling qualities. Finally, the paper reports experimental results of simulated visual shipboard approaches conducted with four experimental test pilots for low- and high-intensity ship motions. The results indicate improved piloting performance, mitigation of pilot-induced oscillations, lower workload, improved handling, and improved perceived safety for fleet pilots for the proposed visual and control augmentation techniques.","PeriodicalId":50017,"journal":{"name":"Journal of the American Helicopter Society","volume":null,"pages":null},"PeriodicalIF":1.5,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70218519","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

Loads Transfer Principles of Coaxial Helicopter Rotors 同轴直升机旋翼载荷传递原理

IF 1.5 4区工程技术

Journal of the American Helicopter Society Pub Date : 2022-01-01 DOI: 10.4050/jahs.68.012008

D. Han, G. Barakos

引用次数: 0