Design and Analytical Study of a Rotor Airfoil PDF Download
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Author: L. U. Dadone
Publisher:
ISBN:
Category :
Languages : en
Pages : 100
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Book Description
Author: L. U. Dadone
Publisher:
ISBN:
Category :
Languages : en
Pages : 100
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 120
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Author: Gene J. Bingham
Publisher:
ISBN:
Category :
Languages : en
Pages : 16
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Book Description
An analytical investigation has been initiated to define the lift coefficient - Mach number characteristics of airfoils of potential interest for helicopter application. Then, this analysis was extended to determine the relative importance of the airfoil geometric parameters such as thickness, thickness distribution, leading-edge radius, camber, and camber distribution on lift-Mach number characteristics.
Author: Richard Eppler
Publisher: Springer Science & Business Media
ISBN: 3662026465
Category : Technology & Engineering
Languages : en
Pages : 569
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Book Description
This detailed book describes a procedure for the design and analysis of subsonic airfoils. Contains 116 new airfoils for a wide range of Reynolds numbers and application requirements, including the input data for the computer code.
Author: Gene J. Bingham
Publisher:
ISBN:
Category : Drag (Aerodynamics)
Languages : en
Pages : 36
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Author: Lan Ding
Publisher:
ISBN:
Category : Aerospace engineering
Languages : en
Pages : 172
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Book Description
Helicopters are prone to high vibration with its elastic blades whirling in a turbulent aerodynamic environment. The high vibration leads to discomfort of crew and passengers and shortens service life of on-board avionics, structures, and mechanical parts. The primary source of helicopter vibration is the main rotor. Since rotor hub loads are the summation of loads on each blade, the vibratory loads, for a rotor with identical blades, consist of harmonics of integer multiples of the rotational speed. A conventional vibration reduction process (only handles blade-number related harmonics) can be implemented. For a rotor with dissimilar blades, either in terms of inertia or aerodynamics, the vibratory rotor hub loads consist of a full spectrum of harmonics related to the rotor speed. In order to reduce the vibration in such a large range of frequency content, a novel approach named rotor smoothing is needed. This dissertation investigates a helicopter rotor smoothing process with a continuous trailing-edge flap (CTEF). The CTEF is a monolithic active blade control design with no mechanical linkages compared to the conventional discrete trailing-edge flap (DTEF). In this design, micro fiber composite (MFC) layers are embedded inside the airfoil to deform the trailing-edge when voltages are applied to the MFC. The CTEF airfoil sectional analysis and design optimization are iipresented in the first part of this dissertation. Several steps are conducted to perform this sectional analysis. First, a computational fluid dynamics (CFD) analysis is developed using OpenFOAM to study the aerodynamics of the CTEF airfoil. Next, a reduced-order structural analysis is used to predict the deflection of the actuated CTEF airfoil. Then, an aero-structural coupling procedure is developed to calculate the CTEF airfoil deflection under both actuation and aerodynamic loads. Finally, the coupling procedure is validated using the static structural bench test and wind tunnel test data from previous studies. The CTEF airfoil displacements are calculated for three different actuation voltages - 0 and ℗ł750 V at different far-field velocities. Predicted deformation as well as aerodynamic coefficients of the baseline and actuated CTEF airfoil are calculated and compared well with the test data. To obtain the optimal CTEF airfoil layouts to maximize its actuation output, a gradient-based optimization procedure is developed. The MFC ply parameters are set as the optimization process variables with aerodynamic coefficients as the object function. The MFC parameters include bender lengths, ply numbers, and core area materials, which are filled in between upper and lower MFC stacks. The optimization with and without aerodynamic loads is conducted and analyzed. Core area shapes designed with second-order and third-order polynomial curvatures are studied. Once the optimal sectional design is obtained, the variational-asymptotical beam sectional analysis (VABS) is used to calculate the beam sectional properties for applying the CTEF airfoil to helicopter blades. To study a helicopter rotor with the CTEF airfoil on the blade, an aeromechanics (elasticity) analysis is developed in the second part of this dissertation. A 4-bladed baseline helicopter rotor model is developed using a multibody dynamics code Dymore. To validate the Dymore rotor models, flight test data are compared with the Dymore predictions. A CTEF airfoil embedded rotor model is then developed using Dymore. A numerical wind tunnel trim is conducted by prescribing a total lift and zero blade flapping. The variation of vibratory rotor loads with different CTEF inputs are presented, and the control authority of the CTEF airfoil is tested. The application of the CTEF airfoil to the rotor smoothing process is promising. To reduce vibration and smooth rotor in operation, a helicopter rotor smoothing process using the CTEF is developed at the last step. Two dissimilar rotor models with unbalanced inertial force and unbalanced aerodynamics are developed. A dissimilar rotor harmonics analysis is conducted and unbalance harmonics introduced by the dissimilarity are identified. A closed-loop regulator is applied to target the identified unbalance harmonics and conventional vibratory harmonics on both dissimilar rotor models. The smoothing processes are shown to be successful for the complete speed range, and the harmonics are compared before and after the smoothing process. The maximum harmonics reduction of the vertical hub force is 60%. To manage more hub loads harmonics with less flap motion inputs, a higher-harmonic-control (HHC) controller is developed and applied to the rotor smoothing. A rotor with identical blades open-loop flap motion sweep is conducted to validate the HHC controller. A rotor smoothing, targeting the full spectrum harmonics on the unbalanced inertia model, is conducted. The reduction rate reaches 40%.
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722163167
Category :
Languages : en
Pages : 80
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Book Description
A wind tunnel investigation was conducted to determine the 2-D aerodynamic characteristics of a new rotorcraft airfoil designed for application to the tip region (stations outboard of 85 pct. radius) of a helicopter main rotor blade. The new airfoil, the RC(6)-08, and a baseline airfoil, the RC(3)-08, were investigated in the Langley 6- by 28-inch transonic tunnel at Mach numbers from 0.37 to 0.90. The Reynolds number varied from 5.2 x 10(exp 6) at the lowest Mach number to 9.6 x 10(exp 6) at the highest Mach number. Some comparisons were made of the experimental data for the new airfoil and the predictions of a transonic, viscous analysis code. The results of the investigation indicate that the RC(6)-08 airfoil met the design goals of attaining higher maximum lift coefficients than the baseline airfoil while maintaining drag divergence characteristics at low lift and pitching moment characteristics nearly the same as those of the baseline airfoil. The maximum lift coefficients of the RC(6)-08 varied from 1.07 at M=0.37 to 0.94 at M=0.52 while those of the RC(3)-08 varied from 0.91 to 0.85 over the same Mach number range. At lift coefficients of -0.1 and 0, the drag divergence Mach number of both the RC(6)-08 and the RC(3)-08 was 0.86. The pitching moment coefficients of the RC(6)-08 were less negative than those of the RC(3)-08 for Mach numbers and lift coefficients typical of those that would occur on a main rotor blade tip at high forward speeds on the advancing side of the rotor disk. Noonan, Kevin W. Langley Research Center...
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 26
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Book Description
Author:
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 1084
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Book Description
Author: W. Z. Stepniewski
Publisher: Courier Corporation
ISBN: 0486318516
Category : Technology & Engineering
Languages : en
Pages : 640
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Book Description
DIVClear, concise text covers aerodynamic phenomena of the rotor and offers guidelines for helicopter performance evaluation. Originally prepared for NASA. Prefaces. New Indexes. 10 black-and-white photos. 537 figures. /div
