scholarly journals Numerical and Experimental Estimation of the Efficiency of a Quadcopter Rotor Operating at Hover

Energies ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 261 ◽  
Author(s):  
Andres G. ◽  
Juan S. ◽  
Omar López ◽  
Laura Suárez C, ◽  
Jaime A. Escobar
Keyword(s):  
Pressure Coefficient ◽  
Tip Vortex ◽  
Small Scale ◽  
Viscous Effects ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Computational Fluid Dynamics Cfd ◽  
Experimental Values ◽  
Thrust And Torque

Globalization has led to an increase in the use of small copters for different activities such as geo-referencing, agricultural fields monitoring, survillance, among others. This is the main reason why there is a strong interest in the performance of small-scale propellers used in unmanned aerial vehicles. The flow developed by rotors is complex and the estimation of its aerodynamic performance is not a trivial process. In addition, viscous effects, when the rotor operates at low Reynolds, affect its performance. In the present paper, two different computational methods, Computational Fluid Dynamics (CFD) and the Unsteady Vortex Lattice Method (UVLM) with a viscous correction, were used to study the performance of an isolated rotor of a quadcopter flying at hover. The Multi Reference Frame model and transition S S T κ - ω turbulence model were used in the CFD simulations. The tip vortex core growth was used to account for the viscous effects in the UVLM. The wake structure, pressure coefficient, thrust and torque predictions from both methods are compared. Thrust and torque results from simulations were validated by means of experimental results of a characterization of a single rotor. Finally, figure of merit of the rotor is evaluated showing that UVLM overestimates the efficiency of the rotor; meanwhile, CFD predictions are close to experimental values.

scholarly journals Stability Characteristics of Wing Span and Sweep Morphing for Small Unmanned Air Vehicle: A Mathematical Analysis

2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Hafiz Muhammad Umer ◽  
Adnan Maqsood ◽  
Rizwan Riaz ◽  
Shuaib Salamat
Keyword(s):  
Equations Of Motion ◽  
Small Scale ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Flight Stability ◽  
Longitudinal Modes ◽  
Flight Vehicles ◽  
Stability Derivatives ◽  
Wing Sweep ◽  
Wing Morphing

Morphing aircraft are the flight vehicles that can reconfigure their shape during the flight in order to achieve superior flight performance. However, this promising technology poses cross-disciplinary challenges that encourage widespread design possibilities. This research aims to investigate the flight dynamic characteristics of various morphed wing configurations that can be incorporated in small-scale UAVs. The objective of this study was to analyze the effects of in-flight wing sweep and wingspan morphing on aerodynamic and flight stability characteristics. Longitudinal, lateral, and directional characteristics were evaluated using linearized equations of motion. An open-source code based on Vortex Lattice Method (VLM) assuming quasi-steady flow was used for this purpose. Trim points were identified for a range of angles of attack in prestall regime. The aerodynamic coefficients and flight stability derivatives were compared for the aforementioned morphing schemes with a fixed-wing counterpart. The results indicated that wingspan morphing is better than wing sweep morphing to harness better aerodynamic advantages with favorable flight stability characteristics. However, extension in wingspan beyond certain limits jeopardizes the advantages. Dynamically, wingspan and sweep morphing schemes behave in an exactly opposite way for longitudinal modes, whereas lateral-directional dynamics act in the same fashion for both morphing schemes. The current study provided a baseline to explore the advanced flight dynamic aspects of employed wing morphing schemes.

A Prescribed-Wake Vortex Lattice Method for Preliminary Design of Co-Axial, Dual-Rotor Wind Turbines

2016 ◽  
Vol 138 (6) ◽  
Author(s):  
Aaron Rosenberg ◽  
Anupam Sharma
Keyword(s):  
Wind Turbines ◽  
Vortex Lattice ◽  
Navier Stokes ◽  
Wake Vortex ◽  
Preliminary Design ◽  
Lattice Method ◽  
Vortex Lattice Method ◽  
Trailing Vortices ◽  
Computational Fluid Dynamics Cfd ◽  
Reynolds Averaged Navier Stokes

This paper extends the prescribed-wake vortex lattice method (VLM) to perform aerodynamic analysis of dual-rotor wind turbines (DRWTs). A DRWT turbine consists of a large, primary rotor placed co-axially behind a smaller, secondary rotor. The additional vortex system introduced by the secondary rotor of a DRWT is modeled while taking into account the singularities that can occur when the trailing vortices from the secondary (upstream) rotor interact with the bound vortices of the main (downstream) rotor. Pseudo-steady assumption is invoked, and averaging over multiple relative rotor positions is performed to account for the primary and secondary rotors operating at different rotational velocities. The VLM solver is first validated against experiments and blade element momentum theory results for a conventional, single-rotor turbine. The solver is then verified for two DRWT designs against results from two computational fluid dynamics (CFD) methods: (1) Reynolds-averaged Navier–Stokes CFD with an actuator disk representation of the turbine rotors and (2) large-eddy simulations with an actuator line model. Radial distributions of sectional torque force and angle of attack show reasonable agreement between the three methods. Results of parametric sweeps performed using VLM agree qualitatively with the Reynolds-averaged Navier–Stokes (RANS) CFD results demonstrating that the proposed VLM can be used to guide preliminary design of DRWTs.

Aero Engine Axi-Symmetric Convergent-Constant Area Intake 3D Simulation Using a Panel Method Approach

2005 ◽  
Author(s):  
Ioannis Templalexis ◽  
Pericles Pilidis ◽  
Geoffrey Guindeuil ◽  
Petros Kotsiopoulos ◽  
Vassilios Pachidis
Keyword(s):  
Three Dimensional ◽  
Internal Flow ◽  
Navier Stokes ◽  
Lattice Method ◽  
Simulation Code ◽  
Lower Lip ◽  
Vortex Lattice Method ◽  
Constant Area ◽  
Computational Fluid Dynamics Cfd ◽  
General Effort

This study has been carried out as a part of a general effort to develope a powerful simulation code, based on the Vortex Lattice Method (VLM), capable of simulating adequately accurate and comparatively fast, internal flow regimes. It utilizes a convergent – (nearly) constant area axi-symmetric intake three dimensional geometry, emerged as a surface of revolution from the CFM56-5B2 lower lip geometry. The study focuses on the three most critical planes, which are the inlet of the intake, the outlet of the diverging section and the outlet of the intake. Moreover, the sensitivity of the simulation on the variation of the Angle Of Attack (AOA) is tested for four different settings equally spaced, ranging from 0 to 20 degrees. The comparison is carried out on both two-dimensional velocity distributions and average values. The VLM simulation code was based on an existing code, which was modified in order to be adapted to the Reynolds Average Navier-Stokes (RANS) Computational Fluid Dynamics (CFD) boundary conditions.

Generalized vortex lattice method for planar supersonic flow

AIAA Journal ◽  
1997 ◽  
Vol 35 ◽  
pp. 1230-1233
Author(s):  
Paulo A. O. Soviero ◽  
Hugo B. Resende
Keyword(s):  
Supersonic Flow ◽  
Vortex Lattice ◽  
Lattice Method ◽  
Vortex Lattice Method

scholarly journals Static Aeroelastic Characteristics of Morphing Trailing-Edge Wing Using Geometrically Exact Vortex Lattice Method

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Sen Mao ◽  
Changchuan Xie ◽  
Lan Yang ◽  
Chao Yang
Keyword(s):  
Vortex Lattice ◽  
Deflection Angle ◽  
Aircraft Design ◽  
Analysis Method ◽  
Lattice Method ◽  
Trailing Edge ◽  
Vortex Lattice Method ◽  
Analysis And Design ◽  
Aeroelastic Analysis ◽  
Typical Model

A morphing trailing-edge (TE) wing is an important morphing mode in aircraft design. In order to explore the static aeroelastic characteristics of a morphing TE wing, an efficient and feasible method for static aeroelastic analysis has been developed in this paper. A geometrically exact vortex lattice method (VLM) is applied to calculate the aerodynamic forces. Firstly, a typical model of a morphing TE wing is chosen and built which has an active morphing trailing edge driven by a piezoelectric patch. Then, the paper carries out the static aeroelastic analysis of the morphing TE wing and corresponding simulations were carried out. Finally, the analysis results are compared with those of a traditional wing with a rigid trailing edge using the traditional linearized VLM. The results indicate that the geometrically exact VLM can better describe the aerodynamic nonlinearity of a morphing TE wing in consideration of geometrical deformation in aeroelastic analysis. Moreover, out of consideration of the angle of attack, the deflection angle of the trailing edge, among others, the wing system does not show divergence but bifurcation. Consequently, the aeroelastic analysis method proposed in this paper is more applicable to the analysis and design of a morphing TE wing.

Optical and Chemical Characterization of Aerosols Emitted from Coal, Heavy and Light Fuel Oil, and Small-Scale Wood Combustion

2013 ◽  
Vol 48 (1) ◽  
pp. 827-836 ◽  
Author(s):  
Anna K. Frey ◽  
Karri Saarnio ◽  
Heikki Lamberg ◽  
Fanni Mylläri ◽  
Panu Karjalainen ◽  
...  
Keyword(s):  
Chemical Characterization ◽  
Fuel Oil ◽  
Small Scale ◽  
Wood Combustion

A Hybrid Viscous/Potential Flow Method for the Prediction of the Performance of Podded and Ducted Propellers

2009 ◽  
Author(s):  
Spyros A. Kinnas ◽  
Shu-Hao Chang ◽  
Yi-Hsiang Yu ◽  
Lei He
Keyword(s):  
Viscous Flow ◽  
Lattice Method ◽  
Viscous Potential Flow ◽  
Flow Solver ◽  
Vortex Lattice Method ◽  
Ducted Propeller ◽  
Hybrid Numerical Method ◽  
Convergence Study ◽  
Effective Wake ◽  
Ducted Propellers

This paper presents the analysis of the performance for podded and ducted propellers using a hybrid numerical method, which couples a vortex lattice method (MPUF-3A) for the unsteady analysis of propellers and a viscous flow solver (NS-3X or FLUENT) for the prediction of the viscous flow around propulsors and the drag force on the pod and duct surfaces. The time averaged propeller force distributions are considered as source terms (body force) in the momentum equations of NS-3X and FLUENT. The effects of viscosity on the effective wake and on the performance of the propeller blade, as well as on the predicted pod and duct forces, are assessed. The convergence study of circulation distributions with number of lattices is reported in the ducted propeller case. Finally, the prediction of the performance for podded propellers (both single pull-type and twin-type) and ducted propellers from the present method is validated against existing experimental data.

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