scholarly journals Load prediction of hingeless helicopter rotors including drivetrain dynamics

2021 ◽  
Author(s):  
Felix Weiss ◽  
Christoph Kessler
Keyword(s):  
Wind Tunnel ◽  
Structural Model ◽  
Wind Tunnel Test ◽  
Major Change ◽  
Load Prediction ◽  
Baseline Case ◽  
Time Marching ◽  
Free Wake ◽  
Blade Loads ◽  
Cruise Flight

AbstractIn contrast to analyses with constrained hub speed, the present study includes the dynamic response of coupled rotor-drivetrain modes in the aeromechanic simulation of rotor blade loads. The structural model of the flexible Bo105 rotor-drivetrain system is coupled to aerodynamics modeled by an analytical formulation of unsteady blade element loads combined with a generalized dynamic wake or a free wake, respectively. For two flight states, i. e. cruise flight and large blade loading, a time-marching autopilot trim of the rotor-drivetrain system in wind tunnel configuration is performed. The simulation results are compared to those of a baseline case with constant rotor hub speed. The comparison reveals a major change in the blade passage frequency harmonics of the lead-lag loads. Beside the full drivetrain model, reduced models are shown to accurately represent the drivetrain influence on blade loads, if the eigenfrequency of the coupled second collective lead-lag/drivetrain mode is properly predicted. In a sensitivity analysis, this eigenfrequency is varied by stiffness modification of a reduced drivetrain model. The resulting changes in blade loads are correlated to this eigenfrequency, which serves as a simple though accurate classification of the drivetrain regarding its influence on vibratory blade loads. Finally, the potential to improve lead-lag load predictions by application of a drivetrain model is demonstrated through the comparison of simulated loads with measurements from a wind tunnel test.

scholarly journals The Challenge of Controlling a Small Mars Plane

2020 ◽  
Author(s):  
Seiki Chiba ◽  
Mikio Waki
Keyword(s):  
Wind Tunnel ◽  
Power Control ◽  
High Power ◽  
Structural Model ◽  
High Efficiency ◽  
Wind Tunnel Test ◽  
Martian Atmosphere ◽  
Planetary Exploration ◽  
Control Surface ◽  
Dielectric Elastomers

Dielectric elastomers (DEs) are lightweight and high-power, making them ideal for power control in a planetary exploration spacecraft. In this chapter, we will discuss the control of an exploration airplane exploring the surface of Mars using DEs. This airplane requires lightweight and powerful actuators to fly in the rare Martian atmosphere. DEs are a possible candidate for use as actuator controlling the airplane since they have high power, and high efficiency. A structural model of a wing having a control surface, a DE, and a linkage was built and a wind tunnel test of a control surface actuation using a DE actuator was carried out.

Blade Structural Load/Airload Correlation on a Slowed Mach-Scaled Rotor at High Advance Ratios

2020 ◽  
Vol 65 (4) ◽  
pp. 1-14
Author(s):  
Xing Wang ◽  
Yong Su Jung ◽  
James Baeder ◽  
Inderjit Chopra
Keyword(s):  
Wind Tunnel ◽  
Structural Model ◽  
Reverse Flow ◽  
Pressure Sensors ◽  
Wind Tunnel Test ◽  
Design Feature ◽  
Flow Region ◽  
Rotor Blades ◽  
Data Correlation ◽  
Advance Ratio

To expand the cruise speed of a compound helicopter, alleviating the compressibility effects on the advancing side with reduced rotor RPM is proved to be an effective design feature, which results in high advance ratio flight regime. To investigate the aerodynamic phenomena at high advance ratios and provide data for the validation of analytical tools, a series of wind tunnel tests were conducted progressively in the Glenn L. Martin Wind Tunnel with a 33.5-inch radius fourbladed articulated rotor. In a recent wind tunnel test, the rotor blades were instrumented with pressure sensors and strain gauges at 30% radius, and pressure data were acquired to calculate the sectional airloads by surface integration up to an advance ratio of 0.8. The experimental results of rotor performance, control angles, blade airloads, and structural loads were compared with the predictions of comprehensive analysis and computational fluid dynamics (CFD) analysis coupled with computational structural dynamics (CSD) structural model. The paper focuses on the data correlation between experimental pressure, airload, and structural load data and the CFD/CSD predicted results at various collective and shaft tilt angles. Overall, the data correlation was found satisfactory, and the study provided some insights into the aerodynamic mechanisms that affect the rotor airload and performance, in particular the mechanisms of backward shaft tilt, the effect of hub/shaft wake, and the formation of dynamic stall in the reverse flow region.

Response and Operational Modal Analysis from Wind Tunnel Test of the EOLO Flexible Aircraft

2021 ◽  
Author(s):  
David F. Castillo Zuñiga ◽  
Alain Giacobini Souza ◽  
Roberto G. da Silva ◽  
Luiz Carlos Sandoval Góes
Keyword(s):  
Wind Tunnel ◽  
Modal Analysis ◽  
Wind Tunnel Test ◽  
Operational Modal Analysis ◽  
Flexible Aircraft

DEVELOPMENT OF A RAPID PROTOTYPING METHODOLOGY FOR WIND TUNNEL TEST MODEL DESIGN

2019 ◽  
Author(s):  
Bruno Ricardo Massucatto Padilha ◽  
Guilherme Barufaldi ◽  
ROBERTO GIL ANNES DA SILVA
Keyword(s):  
Wind Tunnel ◽  
Rapid Prototyping ◽  
Wind Tunnel Test ◽  
Test Model ◽  
Model Design

Rancang Bangun Piranti Lunak Pengolah Data Pasca Pengujian Terowongan Angin Kecepatan Rendah Indonesia

2016 ◽  
Vol 7 (2) ◽  
pp. 131-138
Author(s):  
Ivransa Zuhdi Pane
Keyword(s):  
Wind Tunnel ◽  
Wind Tunnel Test ◽  
Test Results ◽  
Effective Solution ◽  
Post Processing ◽  
Prototype Development ◽  
Design Activities ◽  
Index Terms ◽  
Test Objects ◽  
Processing Requirement

Data post-processing plays important roles in a wind tunnel test, especially in supporting the validation of the test results and further data analysis related to the design activities of the test objects. One effective solution to carry out the data post-processing in an automated productive manner, and thus eliminate the cumbersome conventional manual way, is building a software which is able to execute calculations and have abilities in presenting and analyzing the data in accordance with the post-processing requirement. Through several prototype development cycles, this work attempts to engineer and realize such software to enhance the overall wind tunnel test activities. Index Terms—software engineering, wind tunnel test, data post-processing, prototype, pseudocode

scholarly journals Investigation of the Time Dependence of Wind-Induced Aeroelastic Response on a Scale Model of a High-Rise Building

2021 ◽  
Vol 11 (8) ◽  
pp. 3315
Author(s):  
Fabio Rizzo
Keyword(s):  
Wind Tunnel ◽  
Time Dependence ◽  
Wind Tunnel Test ◽  
Structural Response ◽  
Cumulative Distribution ◽  
Scale Model ◽  
Acquisition Time ◽  
Test Results ◽  
High Rise ◽  
High Rise Building

Experimental wind tunnel test results are affected by acquisition times because extreme pressure peak statistics depend on the length of acquisition records. This is also true for dynamic tests on aeroelastic models where the structural response of the scale model is affected by aerodynamic damping and by random vortex shedding. This paper investigates the acquisition time dependence of linear transformation through singular value decomposition (SVD) and its correlation with floor accelerometric signals acquired during wind tunnel aeroelastic testing of a scale model high-rise building. Particular attention was given to the variability of eigenvectors, singular values and the correlation coefficient for two wind angles and thirteen different wind velocities. The cumulative distribution function of empirical magnitudes was fitted with numerical cumulative density function (CDF). Kolmogorov–Smirnov test results are also discussed.

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