On the Edge Singularity of the Actuator Disk Model

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Jean-Jacques Chattot
Keyword(s):  
Vortex Tube ◽  
Axisymmetric Flow ◽  
Leading Edge ◽  
Two Dimensions ◽  
Disk Model ◽  
Edge Singularity ◽  
Vorticity Distribution ◽  
Actuator Disk ◽  
Constant Vorticity ◽  
Cylindrical Vortex

Abstract In this technical brief, the classic actuator disk theory is revisited with a view to shed some light on the singularity of the flow at the edge of the disk where the vortex tube starts and where vorticity is generated. The study is carried out using small perturbation assumption in two-dimensions and simplified boundary conditions in all cases. The problem of the two-dimensional thin cambered plate with constant vorticity distribution is solved and the leading edge singularity is analyzed as it is believed to be relevant to the axisymmetric flow at the actuator disk edge. Next, the velocity components induced by the cylindrical vortex tube of constant vorticity are obtained via the Biot–Savart law and the near edge behavior is investigated. It is shown that the velocity components behavior is consistent with that of the thin cambered plate with constant loading, thus reinforcing the notion that the axisymmetric slip-line behaves as r − R ∝ −xlnx near the disk edge.

The Design of a Large Diameter Axial Flow Fan for Air-Cooled Heat Exchanger Applications

2017 ◽  
Author(s):  
Michael B. Wilkinson ◽  
Johan van der Spuy ◽  
Theodor W. von Backström
Keyword(s):  
Flow Field ◽  
Large Diameter ◽  
Axial Flow ◽  
Pressure Rise ◽  
Design Procedure ◽  
Axial Flow Fan ◽  
Disk Model ◽  
Actuator Disk ◽  
Static Efficiency ◽  
Air Cooled Heat Exchanger

An axial flow fan design methodology is developed to design large diameter, low pressure rise, rotor-only fans for large air-cooled heat exchangers. The procedure aims to design highly efficient axial flow fans that perform well when subjected to off design conditions commonly encountered in air-cooled heat exchangers. The procedure makes use of several optimisation steps in order to achieve this. These steps include optimising the hub-tip ratio, vortex distribution, blading and aerofoil camber distributions in order to attain maximum total-to-static efficiency at the design point. In order to validate the design procedure a 24 ft, 8 bladed axial flow fan is designed to the specifications required for an air-cooled heat exchanger for a concentrated solar power (CSP) plant. The designed fan is numerically evaluated using both a modified version of the actuator disk model and a three dimensional periodic fan blade model. The results of these CFD simulations are used to evaluate the design procedure by comparing the fan performance characteristic data to the design specification and values calculated by the design code. The flow field directly down stream of the fan is also analysed in order to evaluate how closely the numerically predicted flow field matches the designed flow field, as well as determine whether the assumptions made in the design procedure are reasonable. The fan is found to meet the required pressure rise, however the fan total-to-static efficiency is found to be lower than estimated during the design process. The actuator disk model is found to under estimate the power consumption of the fan, however the actuator disk model does provide a reasonable estimate of the exit flow conditions as well as the total-to-static pressure characteristic of the fan.

scholarly journals The CFD Investigation of Two Non-Aligned Turbines Using Actuator Disk Model and Overset Grids

2014 ◽  
Vol 524 ◽  
pp. 012144
Author(s):  
I O Sert ◽  
S C Cakmakcioglu ◽  
O Tugluk ◽  
N Sezer-Uzol
Keyword(s):  
Disk Model ◽  
Overset Grids ◽  
Actuator Disk

On the Edge Singularity of an Actuator Disk with Large Constant Normal Load

1977 ◽  
Vol 21 (02) ◽  
pp. 125-131
Author(s):  
G. H. Schmidt ◽  
J. A. Sparenberg
Keyword(s):  
Potential Theory ◽  
Normal Load ◽  
Curved Surface ◽  
Singular Behavior ◽  
Nonlinear Potential Theory ◽  
Edge Singularity ◽  
Actuator Disk ◽  
Nonlinear Potential ◽  
Constant Normal Load ◽  
Special Case

In this paper some aspects of the nonlinear potential theory of actuator disks are considered. A rather general formulation of the problem for a prescribed load on a curved surface is given. For the special case of constant normal load and no incoming velocity the singular behavior of the flow at the edge of the disk is discussed.

A Note on the Vorticity Distribution on the Surface of Slender Delta Wings with Leading Edge Separation

1961 ◽  
Vol 65 (603) ◽  
pp. 195-198 ◽  
Author(s):  
B. J. Elle ◽  
J. P. Jones
Keyword(s):  
Experimental Evidence ◽  
Delta Wing ◽  
Leading Edge ◽  
Water Tunnel ◽  
Delta Wings ◽  
Vorticity Distribution ◽  
Edge Separation

A description is given of the distribution of vorticity in the surface of thin wings with large leading edge sweep. Although the delta wing is chosen as the basic plan form the deductions are general and applicable to other types of wing. The conclusions are illustrated with experimental evidence from a water tunnel.

scholarly journals On Predicting the Phenomenon of Surface Flow Convergence in Wind Farms

2014 ◽  
Author(s):  
Suganthi Selvaraj ◽  
Anupam Sharma
Keyword(s):  
Wind Farm ◽  
Wind Farms ◽  
Surface Flow ◽  
Maximum Efficiency ◽  
Horizontal Axis Wind Turbine ◽  
Disk Model ◽  
Systematic Analysis ◽  
Actuator Disk ◽  
Momentum Theory ◽  
Flow Convergence

A systematic analysis of a single-rotor horizontal axis wind turbine aerodynamics is performed to obtain a realistic potential maximum efficiency. It is noted that by including the effects of swirl, viscosity and finite number of blades, the maximum aerodynamic efficiency of a HAWT is within a few percentage points of the efficiency of commercially-available turbines. The need for investigating windfarm (as a unit) aerodynamics is thus highlighted. An actuator disk model is developed and implemented in the OpenFOAM software suite. The model is validated against 1-D momentum theory, blade element momentum theory, as well as against experimental data. The validated actuator disk model is then used to investigate an interesting microscale meteorological phenomenon called “flow convergence” caused by an array of wind turbines. This phenomenon is believed to be caused by the drop of pressure in wind farms. Wind farm numerical simulations are conducted with various approximations to investigate and explain the flow convergence phenomenon.

scholarly journals Ducted Propeller Flow Analysis by Means of a Generalized Actuator Disk Model

2014 ◽  
Vol 45 ◽  
pp. 1107-1115 ◽  
Author(s):  
Rodolfo Bontempo ◽  
Massimo Cardone ◽  
Marcello Manna ◽  
Giovanni Vorraro
Keyword(s):  
Flow Analysis ◽  
Disk Model ◽  
Actuator Disk ◽  
Ducted Propeller

Developing the Actuator Disk Model to Predict the Fluid–Structure Interaction in Numerical Simulation of Multimegawatt Wind Turbine Blades

2019 ◽  
Vol 142 (3) ◽  
Author(s):  
Ali Behrouzifar ◽  
Masoud Darbandi
Keyword(s):  
Numerical Methods ◽  
Wind Turbine ◽  
Fluid Structure Interaction ◽  
Cone Angle ◽  
Disk Model ◽  
Fluid Structure ◽  
Aerodynamic Loads ◽  
Structure Interaction ◽  
Actuator Disk ◽  
Analytical Approaches

Abstract The fluid–structure interaction (FSI) is generally addressed in multimegawatt wind turbine calculations. From the fluid flow perspective, the semi-analytical approaches, like actuator disk (AD) model, were commonly used in wind turbine rotor calculations. Indeed, the AD model can effectively reduce the computational cost of full-scale numerical methods. Additionally, it can substantially improve the results of pure analytical methods. Despite its great advantages, the AD model has not been developed to simulate the FSI problem in wind turbine simulations. This study first examines the effect of constant (rigid) cone angle on the performance of the chosen benchmark wind turbine. As a major contribution, this work subsequently extends the rigid AD model to nonrigid applications to suitably simulate the FSI. The new developed AD-FSI solver uses the finite-volume method to calculate the aerodynamic loads and the beam theory to predict the structural behaviors. A benchmark megawatt wind turbine is simulated to examine the accuracy of the newly developed AD-FSI solver. Next, the results of this solver are compared with the results of other researchers, who applied various analytical and numerical methods to obtain their results. The comparisons indicate that the new developed solver calculates the aerodynamic loads reliably and predicts the blade deflection very accurately.

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