The Application of Actuator Disks to Calculations of the Flow in Turbofan Installations

1997 ◽  
Vol 119 (4) ◽  
pp. 733-741 ◽  
Author(s):  
W. G. Joo ◽  
T. P. Hynes
Keyword(s):  
Three Dimensional ◽  
Flow Fields ◽  
Experimental Results ◽  
Disk Model ◽  
Actuator Disk ◽  
Good Agreement

This paper discusses the application of an actuator disk model to the problem of calculating the asymmetric performance of a turbofan operating behind a nonaxisymmetric intake and due to the presence of the engine pylon. Good agreement between predictions and experimental results is demonstrated. Further validation of the model is obtained by comparison with the results of a three-dimensional calculation of an isolated fan operating with a nonaxisymmetric inlet. Some justification of the neglect of unsteady aspects of the flow in the fan is presented. The quantitative features of the interaction of the pylon and fan flow fields are discussed.

Modeling Hydroplaning and Effects of Pavement Microtexture

2005 ◽  
Vol 1905 (1) ◽  
pp. 166-176 ◽  
Author(s):  
G. P. Ong ◽  
T. F. Fwa ◽  
J. Guo
Keyword(s):  
Three Dimensional ◽  
Flow Simulation ◽  
Experimental Results ◽  
Tire Pressure ◽  
Finite Volume Model ◽  
Proposed Model ◽  
Loss Of Contact ◽  
The One ◽  
Theoretical Considerations ◽  
Good Agreement

Hydroplaning on wet pavement occurs when a vehicle reaches a critical speed and causes a loss of contact between its tires and the pavement surface. This paper presents the development of a three-dimensional finite volume model that simulates the hydroplaning phenomenon. The theoretical considerations of the flow simulation model are described. The simulation results are in good agreement with the experimental results in the literature and with those obtained by the well-known hydroplaning equation of the National Aeronautics and Space Administration (NASA). The tire pressure–hydroplaning speed relationship predicted by the model is found to match well the one obtained with the NASA hydroplaning equation. Analyses of the results of the present study indicate that pavement microtexture in the 0.2- to 0.5-mm range can delay hydroplaning (i.e., raise the speed at which hydroplaning occurs). The paper also shows that the NASA hydroplaning equation provides a conservative estimate of the hydroplaning speed. The analyses in the present study indicate that when the microtexture of the pavement is considered, the hydroplaning speed predicted by the proposed model deviates from the speed predicted by the smooth surface relationship represented by the NASA hydroplaning equation. The discrepancies in hydroplaning speed are about 1% for a 0.1-mm microtexture depth and 22% for a 0.5-mm microtexture depth. The validity of the proposed model was verified by a check of the computed friction coefficient against the experimental results reported in the literature for pavement surfaces with known microtexture depths.

Numerical Calculation of Pressure Fluctuations in the Volute of a Centrifugal Fan

2005 ◽  
Vol 128 (2) ◽  
pp. 359-369 ◽  
Author(s):  
Rafael Ballesteros-Tajadura ◽  
Sandra Velarde-Suárez ◽  
Juan Pablo Hurtado-Cruz ◽  
Carlos Santolaria-Morros
Keyword(s):  
Fluid Dynamics ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Power Spectra ◽  
Operating Conditions ◽  
Experimental Results ◽  
Time Dependent ◽  
Centrifugal Fan ◽  
Wall Pressure Fluctuations ◽  
Good Agreement

In this work, a numerical model has been applied in order to obtain the wall pressure fluctuations at the volute of an industrial centrifugal fan. The numerical results have been compared to experimental results obtained in the same machine. A three-dimensional numerical simulation of the complete unsteady flow on the whole impeller-volute configuration has been carried out using the computational fluid dynamics code FLUENT®. This code has been employed to calculate the time-dependent pressure both in the impeller and in the volute. In this way, the pressure fluctuations in some locations over the volute wall have been obtained. The power spectra of these fluctuations have been obtained, showing an important peak at the blade passing frequency. The amplitude of this peak presents the highest values near the volute tongue, but the spatial pattern over the volute extension is different depending on the operating conditions. A good agreement has been found between the numerical and the experimental results.

A Stochastic Nonlinear Constitutive Law for Concrete

1989 ◽  
Vol 111 (4) ◽  
pp. 443-449 ◽  
Author(s):  
A. Fafitis ◽  
Y. H. Won
Keyword(s):  
Stochastic Model ◽  
Elastic Moduli ◽  
Three Dimensional ◽  
Path Dependency ◽  
Experimental Results ◽  
Constitutive Law ◽  
Induced Anisotropy ◽  
Nonproportional Loading ◽  
Strain Relationship ◽  
Good Agreement

An incremental three-dimensional stress-strain relationship for concrete with induced anisotropy has been developed. The nonlinearity and path-dependency are modeled by expressing the elastic moduli at each increment as function of the octahedral and deviatoric strains, based on a uniaxial stochastic model developed earlier. Predictions of multiaxial response under proportional and nonproportional loading are in good agreement with experimental results.

Prediction Laser Sealed Advanced Ceramic Coatings Dimensions by Using Finite Element Model and Computational Method

2011 ◽  
Vol 264-265 ◽  
pp. 1444-1449
Author(s):  
K.M. Adel ◽  
E.K. Ekhlas ◽  
S.H. Shaker
Keyword(s):  
Heat Affected Zone ◽  
Three Dimensional ◽  
Element Model ◽  
Melting Zone ◽  
Ceramic Coatings ◽  
Experimental Results ◽  
Computational Method ◽  
Zone Model ◽  
Good Prediction ◽  
Good Agreement

A three dimensional FE modeling of the laser surface modification is presented. The design capabilities of the ANSYS (11) software were employed for this purpose. The model calculates the dimensions of melting zone and heat affected zone. Model simulations are compared with experimental results that showed very good agreement. A one dimensional model in V.B language was presented too. The model based on conduction of heat in one dimension neglecting the other losses of heat. The results of VISUAL BASIC were compared with experimental results which showed a very good agreement. The two methods were compared with each other to showing which method have a good prediction compared with experimental results in calculating of fusion zone and heat affected zone "HAZ".

Numerical Research on Flow Field Characteristics within the Slipstream of a Propeller

2012 ◽  
Vol 224 ◽  
pp. 55-60
Author(s):  
Zhong Zhe Duan ◽  
Pei Qing Liu ◽  
Li Chuan Ma
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Scientific Basis ◽  
Disk Model ◽  
Actuator Disk ◽  
Numerical Result ◽  
Light Load ◽  
Strip Theory ◽  
Flow Field Characteristics ◽  
Numerical Research

Numerical research on three dimensional flow field of a propeller and actuator disk model have been made. Under design conditions (headway 66.889m/s, revolving velocity 2575rpm）, the Slipstream flow field after Propeller is solved by RANS equations with structure mesh. Chosen 12 million mesh through verification of reliability analysis. The numerical result consists of the flow field and vortex field in the propeller slipstream. With comparison to the calculation result of standard strip theory and actuator disk model, it is shown that for light load propeller with the side small contraction of slipstream, in the slipstream cross section after 0.6R away from downstream of propeller rotation plane, the axial, circular and radial induced velocity coefficient by Prandtl’s blade tip corrected standard strip theory result; three dimensional flows numerical simulation and actuator disk model are well consistent. It verified the correctness of standard strip theory and also provided scientific basis for the correction of actuator disk model

scholarly journals Numerical Investigation on Steel Square HSS Columns Strengthened with Polymer-mortar

2019 ◽  
pp. 1-25
Author(s):  
Khaled M. El-Sayed ◽  
Ahmed S. Debaiky ◽  
Nader N. Khalil ◽  
Ibrahim M. El-Shenawy
Keyword(s):  
Three Dimensional ◽  
Shell Element ◽  
Fe Analysis ◽  
Experimental Results ◽  
Fe Model ◽  
Cross Sectional ◽  
Axial Strength ◽  
Polymer Mortar ◽  
Slender Columns ◽  
Good Agreement

This paper presents the results of finite element (FE) analysis of axially loaded square hollow structural steel (HSS) columns, strengthened with polymer-mortar materials. Three-dimensional nonlinear FE model of HSS slender columns were developed using thin-shell element, considering geometric and material nonlinearity. The polymer-mortar strengthening layer was incorporated using additional layers of the shell element. The FE model has been performed and then verified against experimental results obtained by the authors [1]. Good agreement was observed between FE analysis and experimental results. The model was then used in an extended parametric study to examine selected AISC square HSS columns with different cross-sectional geometries, slenderness ratios, thicknesses of mortar strengthening layer, overall geometric imperfections, and level of residual stresses. The effectiveness of polymer-mortar in increasing the column’s axial strength is observed. The study also demonstrated that polymer-mortar strengthening materials is more effective for higher slenderness ratios. An equivalent steel thickness is also accounted for the mortar strengthened HSS columns to discuss the effectiveness of polymer-mortar strengthening system. The polymer-mortar strengthening system is more effective for HSS columns with higher levels of out-of-straightness. Level of residual stress has a slight effect on the gain in the column’s axial strength strengthened with polymer-mortar.

scholarly journals Preliminary analysis of lip-wing concept using computational fluid dynamics and actuator disc theory

2021 ◽  
Author(s):  
Peter Walker
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Preliminary Analysis ◽  
Experimental Results ◽  
Disk Model ◽  
Preliminary Results ◽  
Actuator Disk ◽  
Actuator Disc

This thesis presents a preliminary analysis of the lip wing concept proposed by Dusan Stan of Aliptera Aircraft. A inviscid CFD-CAD actuator disk model was used to simulate a comparable geometry to that which was investigated experimental by Aliptera Aircraft. In general, a 10%-12% increase in thrust was produced at an optimal lip wing angle of 30o. This increase in thrust was consistent with the experimental results obtained by Aliptera Aircraft. These preliminary results are promising and encourage further research

A Simplified Method of Using Four-Hole Probes to Measure Three-Dimensional Flow Fields

1985 ◽  
Vol 107 (1) ◽  
pp. 31-35 ◽  
Author(s):  
N. Sitaram ◽  
A. L. Treaster
Keyword(s):  
Flat Plate ◽  
Three Dimensional ◽  
Flow Fields ◽  
Three Dimensional Flow ◽  
Dimensional Flow ◽  
Application Procedure ◽  
Simplified Method ◽  
Theoretical Predictions ◽  
Gradient Effects ◽  
Good Agreement

A simplified method of using four-hole probes to measure three-dimensional flow-fields is presented. This method is similar to an existing calibration and application procedure used for five-hole probes. The new method is demonstrated for two four-hole probes of different geometry. These four-hole probes and a five-hole probe are used to measure the turbulent boundary layer on a flat plate. The results from the three probes are in good agreement with theoretical predictions. The major discrepancies occur near the surface of the flat plate and are attributed to wall vicinity and velocity gradient effects.

A Comparison of Actuator Disc Models for Axial Flow Fans in Large Air-Cooled Heat Exchangers

2016 ◽  
Author(s):  
Michael B. Wilkinson ◽  
Francois G. Louw ◽  
Sybrand J. van der Spuy ◽  
Theodor W. von Backström
Keyword(s):  
Heat Exchangers ◽  
Three Dimensional ◽  
Axial Flow ◽  
Velocity Profiles ◽  
Low Flow ◽  
Disk Model ◽  
Flow Rates ◽  
Fan Performance ◽  
Actuator Disk ◽  
Performance Results

The performance of large mechanical draft air-cooled heat exchangers is directly related to fan performance which is influenced by atmospheric wind conditions, as well as the plant layout. It is often necessary to numerically model the entire system, including fans, under a variety of operating conditions. Full three-dimensional, numerical models of axial flow fans are computationally expensive to solve. Simplified models that accurately predict fan performance at a lesser expense are therefore required. One such simplified model is the actuator disk model (ADM). This model approximates the fan as a disk where the forces generated by the blades are calculated and translated into momentum sources. This model has been proven to give good results near and above the design flow rate of a fan, but not at low flow rates. In order to address this problem two modifications were proposed, namely the extended actuator disk model (EADM) and the reverse engineered empirical actuator disk model (REEADM). The three models are presented and evaluated in this paper using ANSYS FLUENT. The models are simulated at different flow rates representing an axial flow fan test facility. The resulting performance results and velocity fields are compared to each other and to previously simulated three dimensional numerical results, indicating the accuracy of each method. The results show that the REEADM gives the best correlation with experimental performance results at design conditions (ϕ = 0.168) while the EADM gives the best correlation at low flow rates. A comparison of the velocity profiles shows that none of the three models predict the radial velocity distribution at low flow rates correctly, however the correlation improves at flow rates above ϕ = 0.105. In general the upstream velocity profiles, where reversed flow occurs through the fan, are poorly predicted at low flow rates. At the flow rates above ϕ = 0.137 the correlation between the velocity profiles for the simplified modes and the three dimensional results is good.

scholarly journals Preliminary analysis of lip-wing concept using computational fluid dynamics and actuator disc theory

2021 ◽  
Author(s):  
Peter Walker
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Preliminary Analysis ◽  
Experimental Results ◽  
Disk Model ◽  
Preliminary Results ◽  
Actuator Disk ◽  
Actuator Disc

This thesis presents a preliminary analysis of the lip wing concept proposed by Dusan Stan of Aliptera Aircraft. A inviscid CFD-CAD actuator disk model was used to simulate a comparable geometry to that which was investigated experimental by Aliptera Aircraft. In general, a 10%-12% increase in thrust was produced at an optimal lip wing angle of 30o. This increase in thrust was consistent with the experimental results obtained by Aliptera Aircraft. These preliminary results are promising and encourage further research

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