Articles de revues : « Rotorcraft aeromechanics »

1

Chopra, Inderjit. « Rotorcraft Aeromechanics ». Journal of the American Helicopter Society 58, n^o 3 (1 juillet 2013) : 1. http://dx.doi.org/10.4050/jahs.58.037001.

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Leishman, J. Gordon. « Rotorcraft Aeromechanics : Getting through the Dip ». Journal of the American Helicopter Society 55, n^o 1 (1 janvier 2010) : 11001–1100124. http://dx.doi.org/10.4050/jahs.55.011001.

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Rutkowski, Michael J., Gene C. Ruzicka, Robert A. Ormiston, Hossein Saberi et Yoon Jung. « Comprehensive Aeromechanics Analysis of Complex Rotorcraft Using 2GCHAS ». Journal of the American Helicopter Society 40, n^o 4 (1 octobre 1995) : 3–17. http://dx.doi.org/10.4050/jahs.40.3.

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Rutkowski, Michael J., Gene C. Ruzicka, Robert A. Ormiston, Hossein Saberi et Yoon Jung. « Comprehensive Aeromechanics Analysis of Complex Rotorcraft Using 2GCHAS ». Journal of the American Helicopter Society 40, n^o 4 (1 octobre 1995) : 3–17. http://dx.doi.org/10.4050/jahs.40.4.3.

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Lovera, Marco, Patrizio Colaneri et Roberto Celi. « On the Role of Zeros in Rotorcraft Aeromechanics ». Journal of the American Helicopter Society 49, n^o 3 (1 juillet 2004) : 318–27. http://dx.doi.org/10.4050/jahs.49.318.

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Masarati, Pierangelo, Giuseppe Quaranta et Michael Jump. « Experimental and numerical helicopter pilot characterization for aeroelastic rotorcraft–pilot coupling analysis ». Proceedings of the Institution of Mechanical Engineers, Part G : Journal of Aerospace Engineering 227, n^o 1 (16 décembre 2011) : 125–41. http://dx.doi.org/10.1177/0954410011427662.

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Pilot–vehicle interaction represents a critical aspect of aircraft design. Very low-frequency, voluntary although unintentional interaction has been extensively investigated in fixed and rotary wing aeromechanics. Higher frequency, involuntary and thus passive interaction received similar attention in fixed wing aeromechanics, but not as much for rotary wing. The results of an experimental campaign for the characterization of the passive behaviour of rotorcraft pilots' biomechanics are presented. A flight simulator has been used to excite human subjects. The accelerations of their limbs and the motion induced by the vibrations of the limbs in the control inceptors have been recorded. The vertical, longitudinal and lateral directions have been independently excited, while measuring the motion of the arm directly involved in the control inceptor mostly affected by motion in each direction, namely the left and the right arms for the collective and the cyclic sticks, respectively. The frequency domain response has been evaluated; resulting noteworthy behaviour is discussed, addressing its relevance in modelling the passive behaviour of pilots within the bioaeroservoelastic rotorcraft analysis. The measurements of human body impedance, under realistic cockpit motion, are used to identify the direct transfer functions between the motion of the seat and the controls inadvertently fed back into the rotorcraft.

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Johnson, Wayne. « Milestones in Rotorcraft Aeromechanics Alexander A. Nikolsky Honorary Lecture ». Journal of the American Helicopter Society 56, n^o 3 (1 juillet 2011) : 1–24. http://dx.doi.org/10.4050/jahs.56.031001.

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Keßler, Manuel. « Rotorcraft Aeromechanics Simulation - When applied mathematics hits real engineering ». PAMM 17, n^o 1 (décembre 2017) : 133–36. http://dx.doi.org/10.1002/pamm.201710038.

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Yeo, Hyeonsoo, et Robert A. Ormiston. « UH-60A Airloads Workshop—Setting the Stage for the Rotorcraft CFD/CSD Revolution, Part II : Ongoing Progress, Impact, and Lessons Learned ». Journal of the American Helicopter Society 67, n^o 2 (1 avril 2022) : 1–16. http://dx.doi.org/10.4050/jahs.67.022011.

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The UH-60A Airloads Workshop was a unique collaboration of aeromechanics experts from the U.S. Government, industry, and academia to address technical issues that hindered accurate rotor loads predictions. The Airloads Workshop leveraged the NASA/Army UH-60A Airloads flight test and NFAC wind tunnel test data. It functioned continuously for 17 years, from 2001 to 2018, and brought about one of the most important advancements in rotorcraft aeromechanics prediction capabilities by successfully demonstrating high-fidelity coupled computational fluid dynamics (CFD) and computational structural dynamics (CSD) analyses for both steady and maneuvering flight. The article is divided into two parts. Part I surveys the background of rotorcraft CFD/CSD development difficulties, the origins of the Airloads Workshop, and the rapid success achieved during the first phase that consisted of eight Workshops. Part II describes ongoing development during the subsequent two phases of the Airloads Workshop, the Ninth through the 13th, and the 14th through the 31st Workshops. Part II outlines development of CFD/CSD methods to predict rotor airloads for the challenging maneuvering flight condition and also describes the impact of the newly developed CFD/CSD methods and how they were transferred to the larger technical community, opening the door for practical application of CFD methods for designing future advanced rotorcraft. Part II concludes with a discussion of why the Airloads Workshop succeeded and lessons learned from the collaborative effort.

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Yeo, Hyeonsoo, et Robert A. Ormiston. « UH-60A Airloads Workshop—Setting the Stage for the Rotorcraft CFD/CSD Revolution, Part I : Background and Initial Success ». Journal of the American Helicopter Society 67, n^o 2 (1 avril 2022) : 1–17. http://dx.doi.org/10.4050/jahs.67.022010.

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The UH-60A Airloads Workshop was a unique collaboration of aeromechanics experts from the U.S. Government, industry, and academia to address technical issues that hindered accurate rotor loads predictions. The Airloads Workshop leveraged the NASA/Army UH-60A Airloads flight test and NFAC wind tunnel test data. It functioned continuously for 17 years, from 2001 to 2018, and brought about one of the most important advancements in rotorcraft aeromechanics prediction capabilities by successfully demonstrating high-fidelity coupled computational fluid dynamics (CFD) and computational structural dynamics (CSD) analyses for both steady and maneuvering flight. The article is divided into two parts. Part I surveys the background of rotorcraft CFD/CSD development difficulties, the origins of the Airloads Workshop, and the rapid success achieved during the first phase that consisted of eight Workshops. Part II describes ongoing development during the subsequent two phases of the Airloads Workshop, the Ninth through the 13th, and the 14th through the 31st Workshops; the impact of the Airloads Workshop; and the lessons learned. Part I surveys the technical activities that led to a breakthrough for CFD/CSD coupling to successfully predict rotor blade airloads in trimmed steady-level flight conditions. This success illustrated the importance of collaboration among key experts with diverse backgrounds focused on a common objective to advance rotorcraft prediction methods.

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Park, Jae-Sang, et Young Jung Kee. « Rotor aeromechanics study using two different blade property data sets ». Aircraft Engineering and Aerospace Technology 88, n^o 6 (3 octobre 2016) : 873–84. http://dx.doi.org/10.1108/aeat-03-2015-0086.

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Purpose This paper aims to compare the comprehensive rotorcraft analyses using the two different blade section property data sets for the blade natural frequencies, airloads, elastic deformations, the trimmed rotor pitch control angles and the blade structural loads of a small-scale model rotor in a blade vortex interaction (BVI) phenomenon. Design/methodology/approach The two different blade section property data sets for the first Higher-harmonic control Aeroacoustic Rotor Test (HART-I) are considered for the present rotor aeromechanics analyses. One is the blade property data set using the predicted values which is one of the estimated data sets used for the previous validation works. The other data set uses the measured values for an uninstrumented blade. A comprehensive rotorcraft analysis code, CAMRAD II (comprehensive analytical model of rotorcraft aerodynamics and dynamics II), is used to predict the rotor aeromechanics such as the blade natural frequencies, airloads, elastic deformations, the trimmed rotor pitch control angles and the blade structural loads for the three test cases with and without higher-harmonic control pitch inputs. In CAMRAD II modelling with the two different blade property data sets, the blade is represented as a geometrically nonlinear elastic beam, and the multiple-trailer wake with consolidation model is used to consider more elaborately the BVI effect in low-speed descending flight. The aeromechanics analysis result sets using the two different blade section property data sets are compared with each other as well as are correlated with the wind-tunnel test data. Findings The predicted blade natural frequencies using the two different blade section property data sets at non-rotating condition are quite similar to each other except for the natural frequency in the fourth flap mode. However, the natural frequencies using the predicted blade properties at nominal rotating condition are lower than those with the measured blade properties except for the second lead-lag frequency. The trimmed collective pitch control angle with the predicted blade properties is higher than both the wind-tunnel test data and the result using the measured blade properties in all the three test cases. The two different blade property data sets both give reasonable predictions on the blade section normal forces with BVI in the three test cases, and the two analysis results are reasonably similar to each other. The blade elastic deformations at the tip using the measured blade properties are correlated more closely with the wind-tunnel test data than those using the predicted blade properties in most correlation examples. In addition, the predictions of blade structural loads can be slightly or moderately improved by using the measured blade properties particularly for the oscillatory flap bending moments. Finally, the movement of the sectional centre of gravity location of the uninstrumented blade has a moderate influence on the blade elastic twist at the tip in the baseline case and the oscillatory flap bending moment in the minimum noise case. Practical implications The present comparison study on rotor aeromechanics analyses using the two different blade property data sets will show the influence of blade section properties on rotor aeromechanics analysis. Originality/value This paper is the first attempt to compare the aeromechanics analysis results using the two different blade section property data sets for all three test cases (baseline, minimum noise and minimum vibration) of HART-I in low-speed descending flight.

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Sitaraman, Jayanarayanan, Mark Potsdam, Andrew Wissink, Buvaneswari Jayaraman, Anubhav Datta, Dimitri Mavriplis et Hossein Saberi. « Rotor Loads Prediction Using Helios : A Multisolver Framework for Rotorcraft Aeromechanics Analysis ». Journal of Aircraft 50, n^o 2 (mars 2013) : 478–92. http://dx.doi.org/10.2514/1.c031897.

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Cardito, Felice, Riccardo Gori, Jacopo Serafini, Giovanni Bernardini et Massimo Gennaretti. « Space-time accurate finite-state dynamic inflow modeling for aeromechanics of rotorcraft ». Aerospace Science and Technology 95 (décembre 2019) : 105454. http://dx.doi.org/10.1016/j.ast.2019.105454.

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You, Young H., Deokhwan Na et Sung N. Jung. « Data Transfer Schemes in Rotorcraft Fluid-Structure Interaction Predictions ». International Journal of Aerospace Engineering 2018 (2018) : 1–15. http://dx.doi.org/10.1155/2018/3426237.

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For a CFD (computation fluid dynamics)/CSD (computational structural dynamics) coupling, appropriate data exchange strategy is required for the successful operation of the coupling computation, due to fundamental differences between CFD and CSD analyses. This study aims at evaluating various data transfer schemes of a loose CFD/CSD coupling algorithm to validate the higher harmonic control aeroacoustic rotor test (HART) data in descending flight. Three different data transfer methods in relation to the time domain airloads are considered. The first (method 1) uses random data selection matched with the timewise resolution of the CSD analysis whereas the last (method 2) adopts a harmonic filter to the original signals in CFD and CSD analyses. The second (method 3) is a mixture of the two methods. All methods lead to convergent solutions after a few cycles of coupling iterations are marched. The final converged solutions for each of the data transfer methods are correlated with the measured HART data. It is found that both method 1 and method 2 exhibit nearly identical results on airloads and blade motions leading to excellent correlations with the measured data while the agreement is less satisfactory with method 3. The reason of the discrepancy is identified and discussed illustrating CFD-/CSD-coupled aeromechanics predictions.

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Teske, Milton E., Daniel A. Wachspress et Harold W. Thistle. « Prediction of Aerial Spray Release from UAVs ». Transactions of the ASABE 61, n^o 3 (2018) : 909–18. http://dx.doi.org/10.13031/trans.12701.

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Abstract. This article summarizes the ability of CHARM+AGDISP to predict the drift and deposition of sprays released from rotary wing unmanned aerial vehicles (UAVs). This predictive capability results from merging algorithms for spray transport, as found in AGDISP (AGricultural DISPersal), with CHARM (Comprehensive Hierarchical Aeromechanics Rotorcraft Model). The resulting software tracks the release of spray droplets from nozzles on the UAV to deposition on the ground. To date, both AGDISP and CHARM, a code that provides a complete representation of the time-varying, unsteady flow field surrounding a helicopter during transient maneuvering flight near the ground, have been extensively validated. The CHARM+AGDISP software is applied to two UAVs to explore the flow field regimes that present challenges for effective UAV operations. The simulations undertaken indicate flight conditions that yield acceptable deposition levels and minimize drift; inversely, conditions are also identified that result in off-target drift that may be problematic. Keywords: Aerial application, AGDISP, CHARM, Helicopter modeling, Unmanned aerial vehicle (UAV).

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Padfield, Gareth D. « Rotorcraft Handling Qualities Engineering : Managing the Tension between Safety and Performance 32nd Alexander A. Nikolsky Honorary Lecture ». Journal of the American Helicopter Society 58, n^o 1 (1 janvier 2013) : 1–27. http://dx.doi.org/10.4050/jahs.58.011001.

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In this Nikolsky paper, I look back nearly 70 years and highlight particular events that reflect the continual growth of the handling qualities discipline. This growth has brought us to a point where designers have, within their grasp, the performance standards, the criteria and test techniques, the understanding of rotorcraft aeromechanics and control, and the design tools, to ensure that handling deficiencies never again have to define the boundary of the operational flight envelope. This point is considered very important in the evolution of the discipline and the associated flight control technologies. The pilot is a vital component in the rotorcraft system; a nearly perfectly functioning component normally, but one that can be stressed, fatigued, or overloaded, particularly when dealing with the consequences of handing qualities deficiencies, and when managing high tension between flight performance and safety. It is argued that this tension is more manageable when an aircraft has good handling qualities, throughout all missions, including flight in degraded environments and hazardous operations. This paper tells the story of how our industry has arrived at this point, how the standards and the enabling technologies have developed, spurred by user needs, and enabled by research. The paper also looks forward, highlighting how we need to strive for super-Level 1 handling qualities, a state where pilot errors, in any shape or form attributable to deficient flight characteristics, are things of the past.

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Bir, G. S., et I. Chopra. « Aeromechanical stability of rotorcraft with advanced geometry blades ». Mathematical and Computer Modelling 19, n^o 3-4 (février 1994) : 159–91. http://dx.doi.org/10.1016/0895-7177(94)90063-9.

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Hodges, Dewey H., A. Stewart Hopkins, Donald L. Kunz et Howard E. Hinnant. « Introduction to GRASP—General Rotorcraft Aeromechanical Stability Program—A Modern Approach to Rotorcraft Modeling ». Journal of the American Helicopter Society 32, n^o 2 (1 avril 1987) : 78–90. http://dx.doi.org/10.4050/jahs.32.78.

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Öhrle, Constantin, Felix Frey, Jakob Thiemeier, Manuel Keßler et Ewald Kräamer. « Coupled and Trimmed Aerodynamic and Aeroacoustic Simulations for Airbus Helicopters' Compound Helicopter RACER ». Journal of the American Helicopter Society 64, n^o 3 (1 juillet 2019) : 1–14. http://dx.doi.org/10.4050/jahs.64.032003.

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In recent years, various helicopter manufacturers increasingly have been focusing on the development of new high-speed rotorcraft configurations, one of them being the compound helicopter RACER (rapid and cost-efficient rotorcraft) of Airbus Helicopters (AH). However, these new configurations encounter new aeromechanic challenges, in terms of aerodynamic interactions, flight mechanics stability, rotor dynamics, or aeroacoustic noise emission, to name only a few. To support AH at the minimization of risk of RACER's first flight, the Institute of Aerodynamics and Gas Dynamics provides high-fidelity coupled and trimmed aerodynamic and aeroacoustic simulations of the complete helicopter by the application of a multidisciplinary tool chain. In its first part, the work focuses on the description of this advanced tool chain and on important features for the analysis of this new configuration. In the second part, exemplary simulation results for a hover and a high-speed cruise flight condition are shown, and the main aerodynamic interactions between the different components are identified. As expected for this configuration, numerous interactions are found for both flight cases, e.g., main rotor–propeller interaction in hover or main rotor–wing interaction in high-speed flight. Finally, aeroacoustic results are shown for hover with a close look at the propellers' contribution.

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Markiewicz, Richard. « Rotorcraft AeromechanicsW. Johnson Cambridge University Press, The Edinburgh Building, Cambridge, CB2 8RU, UK, 2013. 927pp. Illustrated. £95. ISBN 978-1-107-02807-4. » Aeronautical Journal 119, n^o 1212 (février 2015) : 248–49. http://dx.doi.org/10.1017/s0001924000010393.

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Feil, Roland, et Manfred Hajek. « Aeromechanics of a Coaxial Ultralight Rotorcraft During Turn, Climb, and Descent Flight ». Journal of Aircraft, 1 juillet 2020, 1–10. http://dx.doi.org/10.2514/1.c035684.

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Agarwal, Dheeraj, Linghai Lu, Gareth D. Padfield, Mark D. White et Neil Cameron. « The use of augmented rotor inflow to predict rotorcraft responses in hover and low-speed manoeuvres ». Aeronautical Journal, 28 janvier 2022, 1–19. http://dx.doi.org/10.1017/aer.2021.123.

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Abstract The rotorcraft is a complex dynamical system that demands specialist modelling skills, and a high level of understanding of the aeromechanics arising from the main rotor wake and aerodynamic couplings. One such example is the difficulty predicting off-axis responses, particularly in hover and low-speed flight, associated with induced velocity variation through the rotor disk resulting from the rotor wake distortions. Various approaches have been developed to deal with this phenomenon but usually demand prerequisites of high levels of expertise and profound aerodynamic knowledge. This paper presents a new and practical approach to capturing this wake distortion through an augmented rotor inflow model. The proposed model is coupled with a nonlinear simulation using the FLIGHTLAB environment, and comparisons are made between the simulation results and flight test data from the National Research Council of Canada’s Advanced System Research Aircraft in hover and low speed. Results show good predictability of the proposed nonlinear model structure, demonstrated by its capability to closely match the time responses to multi-step control inputs from flight test. The results reported are part of ongoing research at Liverpool and Cranfield University into rotorcraft simulation fidelity.

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Yeo, Hyeonsoo, et Hossein Saberi. « Tiltrotor Conversion Maneuver Analysis with RCAS ». Journal of the American Helicopter Society, 2021. http://dx.doi.org/10.4050/jahs.66.042010.

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Aeromechanics analysis is performed using the comprehensive analysis code RCAS (Rotorcraft Comprehensive Analysis System) to study the transient conversion maneuver of a tiltrotor. The analytical model is based on the XV-15 research tiltrotor aircraft in size and dynamic characteristics. A generic (not representative of XV-15) tiltrotor control system is developed to simulate a conversion maneuver. Hover and cruise performance of the present XV-15 analytical model is validated against available test data. The conversion calculation begins with a trim analysis at hover, which is followed by the conversion maneuver. During the maneuver analysis, the pilot control model is activated to fly the aircraft following a desired airspeed profile and minimum altitude change. Time histories of vehicle dynamics, rotor controls, rotor flapping, rotor performance, and blade structural loads are investigated for various transient conversion maneuvers. The aircraft acceleration during the transient maneuver has a significant influence on the rotor performance and loads.

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Gul, Seyhan, et Anubhav Datta. « Aeroelastic Loads and Stability of Swept-Tip Hingeless Tiltrotors toward High-Speed Instability-Free Cruise ». Journal of the American Helicopter Society, 2022. http://dx.doi.org/10.4050/jahs.68.012001.

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A hingeless hub tiltrotor with swept-tip blades was examined comprehensively with a new rotorcraft aeromechanics solver developed at the University of Maryland. The solver was verified with hypothetical U.S. Army results and validated with Boeing Model 222 test data from 1972. A 20° sweep back from 80%R increased instability speed to 405 kt, an improvement of more than 75 kt. The key mechanism is the aerodynamic center shift. The trade-off is the increase in control system and blade loads. Fundamental understanding of physics is provided. Proprotor air resonance emerged as the critical phenomenon, not whirl flutter. Predictions in powered mode are necessary. At least the first rotor flap, lag, and torsion modes need to be included. Rotor aerodynamics should use airfoil tables; wing aerodynamics is not important for air resonance. Analysis shows high-speed flight is achievable with 13.5% thick wings but systematic wind tunnel tests with modern equipment are necessary for further validation.

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Articles de revues sur le sujet « Rotorcraft aeromechanics »

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