Development, Validation, and Application of an Optimization Scheme for Impellers of Centrifugal Fans Using Computational Fluid Dynamics-Trained Metamodels

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Konrad Bamberger ◽  
Thomas Carolus ◽  
Julian Belz ◽  
Oliver Nelles
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Objective Function ◽  
Training Data ◽  
Centrifugal Impeller ◽  
Geometrical Parameters ◽  
Computational Domain ◽  
Centrifugal Fan ◽  
Optimization Scheme ◽  
Centrifugal Fans

Abstract A quick method for the design of efficiency-optimal centrifugal fan impellers is presented. It is based on an evolutionary optimization algorithm that identifies the optimal geometrical parameters for a given aerodynamic objective function. The range of the geometrical parameters considered allows covering aerodynamic design points appropriate for the complete class of centrifugal fans. The quickness of the method stems from evaluating the objective function using metamodels. In total, four metamodels, based on local model networks (LMN) and multi-layer perceptrons (MLP), were trained and eventually aggregated to reduce the variance (stochastic) error. The training data consist of approximately 4000 characteristic curves obtained from automated numerical steady-state Reynolds-averaged Navier–Stokes (RANS) flow simulations. The computational domain as well as the number of grid nodes and their distribution in the domain were optimized in a pre-study. For verification, a grid independence study was carried out. In addition, two criteria were defined to detect aerodynamic operating points associated with non-physical performance predictions. Finally, validation was secured with experimental data from three exemplary impeller designs. The proposed optimization scheme requires a costly initial one-time computational fluid dynamics (CFD) effort, but then allows a quick design of centrifugal fan impellers for arbitrary design points. The search for an optimal centrifugal impeller requires less than 1 min on a standard personal computer, while allowing up to 105 objective function evaluations for one search. Moreover, predicted performance curves that always come along with each design were found to be very reliable in comparison with experiments.

Automatic computational fluid dynamics-based procedure for the optimization of a centrifugal impeller

2005 ◽  
Vol 219 (7) ◽  
pp. 549-557 ◽  
Author(s):  
F Martelli ◽  
S Pazzi ◽  
V Michelassi
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
New Technologies ◽  
Geometric Constraints ◽  
Flow Coefficient ◽  
Low Flow ◽  
Centrifugal Impeller ◽  
Geometrical Parameters ◽  
Design Point ◽  
Blade Thickness

A typical centrifugal impeller characterized by a low flow coefficient and cylindrical blades is redesigned by means of an intelligent automatic search program. The procedure consists of a feasible sequential quadratic programming algorithm (Fletcher, R. Practical Methods of optimization, 2000 (Wiley)) coupled to a lazy learning (LL) interpolator 1 to speed-up the process. The program is able to handle geometric constraints to reduce the computational effort devoted to the analysis of non-physical configurations. The objective function evaluator is an in-house developed structured computational fluid dynamics (CFD) code. The LL approx-imator is called each time the stored database can provide a sufficiently accurate performance estimate for a given geometry, thus reducing the effective CFD computations. The impeller is represented by 25 geometric parameters describing the vane in the meridional and s-0 planes, the blade thickness, and the leading edge shape. The optimization is carried out on the impeller design point maximizing the polytropic efficiency with nearly constant flow coefficient and polytropic head. The optimization is accomplished by maintaining unaltered those geometrical parameters which have to be kept fixed in order to make the impeller fit the original stage. The optimization, carried out on a cluster of 16 PCs, is self-learning and leads to a geometry presenting an increased design point efficiency. The program is completely general and can be applied to any component which can be described by a finite number of geometrical parameters and computed by any numerical instrument to provide performance indices. The work presented in this paper was done under the METHOD EC funded project for the implementation of new technologies for optimization of centrifugal compressors.

scholarly journals Design of Road-Side Barriers to Mitigate Air Pollution near Roads

2021 ◽  
Vol 11 (5) ◽  
pp. 2391
Author(s):  
Jose I. Huertas ◽  
Javier E. Aguirre ◽  
Omar D. Lopez Mejia ◽  
Cristian H. Lopez
Keyword(s):  
Fluid Dynamics ◽  
Air Pollution ◽  
Computational Fluid Dynamics ◽  
Sulfur Hexafluoride ◽  
Computational Domain ◽  
Cfd Model ◽  
Near Surface ◽  
The Road ◽  
Pollutant Concentrations ◽  
Highly Correlated

The effects of using solid barriers on the dispersion of air pollutants emitted from the traffic of vehicles on roads located over flat areas were quantified, aiming to identify the geometry that maximizes the mitigation effect of air pollution near the road at the lowest barrier cost. Toward that end, a near road Computational Fluid Dynamics (NR-CFD) model that simulates the dispersion phenomena occurring in the near-surface atmosphere (<250 m high) in a small computational domain (<1 km long), via Computational Fluid Dynamics (CFD) was used. Results from the NR-CFD model were highly correlated (R2 > 0.96) with the sulfur hexafluoride (SF6) concentrations measured by the US-National Oceanic and Atmospheric Administration (US-NOAA) in 2008 downwind a line source emission, for the case of a 6m near road solid straight barrier and for the case without any barrier. Then, the effects of different geometries, sizes, and locations were considered. Results showed that, under all barrier configurations, the normalized pollutant concentrations downwind the barrier are highly correlated (R2 > 0.86) to the concentrations observed without barrier. The best cost-effective configuration was observed with a quarter-ellipse barrier geometry with a height equivalent to 15% of the road width and located at the road edge, where the pollutant concentrations were 76% lower than the ones observed without any barrier.

scholarly journals Theoretical Modeling, Design and Simulation of an Innovative Diverting Valve Based on Coanda Effect

Fluids ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 103
Author(s):  
Giancarlo Comes ◽  
Carlo Cravero
Keyword(s):  
Fluid Dynamics ◽  
Mathematical Model ◽  
Computational Fluid Dynamics ◽  
Additive Manufacturing ◽  
Water Flow ◽  
Coanda Effect ◽  
Geometrical Parameters ◽  
Convex Wall ◽  
Fluidic Device ◽  
Coandǎ Effect

The present work is focused on the study of an innovative fluidic device. It consists of a two-ways diverter valve able to elaborate an inlet water flow and divert it through one of the two outlets without moving parts but as a result of a fluctuation of pressure induced by two actuation ports, or channels. Such apparatus is named Attachment Bi-Stable Diverter (ABD) and is able to work with the effect of the fluid adhesion to a convex wall adjacent to it, this phenomenon is known as Coanda Effect; it generates the force responsible for the fluid attachment and the consequent deviation. The main purpose of this work is to develop a knowhow for the design and development of such particular device. A mathematical model for the ABD has been developed and used to find the relationships between the geometrical parameters and the operative conditions. A configuration has been designed, simulated with a computational fluid dynamics approach. A prototype has been printed with and additive manufacturing printer and tested in laboratory to check the effective working point of the device.

Efficiency limits of fans

2019 ◽  
Vol 234 (5) ◽  
pp. 739-748
Author(s):  
Konrad Bamberger ◽  
Thomas Carolus
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Reynolds Number ◽  
Geometrical Parameter ◽  
The Self ◽  
Complex Geometries ◽  
Relevant Parameter ◽  
Optimization Scheme ◽  
Loss Models ◽  
Definition Of

The purpose of this work is to identify upper efficiency limits of industrial fans such as axial rotor-only fans, axial with guide vanes, centrifugal rotor-only and centrifugal with volute. The efficiency limit is always a function of the class, the design point within the class and the definition of efficiency (total-to-static and total-to-total). The characteristic Reynolds number is another relevant parameter. First, based on analytical and empirical loss models, a theoretical efficiency limit is estimated. A set of idealizing assumptions in the loss models yields efficiencies which are assumed to be an insuperable limit but may be unrealistically high. Second, more realistic efficiency limits are estimated using a computational fluid dynamics-based optimization scheme, seeking for the best designs and hence the maximum achievable efficiencies in all classes. Given the self-imposed constraints in the geometrical parameter space considered, the thus-obtained practical efficiency limits can only be exceeded by admitting more complex geometries of the fans.

On the Use of Atmospheric Boundary Conditions for Axial-Flow Compressor Stall Simulations

2004 ◽  
Vol 127 (2) ◽  
pp. 349-351 ◽  
Author(s):  
M. Vahdati ◽  
A. I. Sayma ◽  
C. Freeman ◽  
M. Imregun
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Boundary Conditions ◽  
Hysteresis Loop ◽  
Axial Flow ◽  
Computational Domain ◽  
Computational Fluid Dynamics Cfd ◽  
Fan Blade ◽  
Flow Compressor ◽  
Speed Characteristic

This paper describes a novel way of prescribing computational fluid dynamics (CFD) boundary conditions for axial-flow compressors. The approach is based on extending the standard single passage computational domain by adding an intake upstream and a variable nozzle downstream. Such a route allows us to consider any point on a given speed characteristic by simply modifying the nozzle area, the actual boundary conditions being set to atmospheric ones in all cases. Using a fan blade, it is shown that the method not only allows going past the stall point but also captures the typical hysteresis loop behavior of compressors.

scholarly journals Computational fluid dynamics analysis of the influence of injection nozzle lateral outflow on the performance of Ranque-Hilsch vortex tube

2014 ◽  
Vol 18 (4) ◽  
pp. 1191-1201 ◽  
Author(s):  
Nader Pourmahmoud ◽  
Alireza Izadi ◽  
Amir Hassanzadeh ◽  
Ashkan Jahangiramini
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Flow Field ◽  
Vortex Tube ◽  
Operating Conditions ◽  
Energy Separation ◽  
Physical Parameters ◽  
Dynamics Analysis ◽  
Computational Domain ◽  
Computational Fluid Dynamics Analysis

In this article computational fluid dynamics analysis of a three-dimensional compressible and turbulent flow has been carried out through a vortex tube. The standard k-? turbulence model is utilized in order to simulate an axisymmetric computational domain. The numerical simulation has focused on the energy separation and flow field patterns of a somewhat nonconventional vortex tube, which is on the basis of creating an external hole at the end of each nozzle. According to the selected nozzles geometry, some of unfavorable phenomena such as shock wave, high pressure regions and appearing of unsymmetrical rotating flow patterns in the vortex chamber would be recovered significantly. In this way the physical parameters of flow field are derived under different both inlet mass flow rates and outlet pressures of nozzles hole (OPH). The results show that increasing OPH value enhanced the cooling capacity of machine in the most of operating conditions.

Computational Fluid Dynamics Modeling of Gas–Liquid Cylindrical Cyclones, Geometrical Analysis

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Juan Carlos Berrio ◽  
Eduardo Pereyra ◽  
Nicolas Ratkovich
Keyword(s):  
Fluid Dynamics ◽  
Experimental Data ◽  
Computational Fluid Dynamics ◽  
Cfd Modeling ◽  
Nozzle Geometry ◽  
Geometrical Parameters ◽  
Experimental Setup ◽  
Dynamics Modeling ◽  
Two Phase ◽  
Mean Square Errors

The gas–liquid cylindrical cyclone (GLCC) is a widely used alternative for gas–liquid conventional separation. Besides its maturity, the effect of some geometrical parameters over its performance is not fully understood. The main objective of this study is to use computational fluid dynamics (CFD) modeling in order to evaluate the effect of geometrical modifications in the reduction of liquid carry over (LCO) and gas carry under (GCU). Simulations for two-phase flow were carried out under zero net liquid flow, and the average liquid holdup was compared with Kanshio (Kanshio, S., 2015, “Multiphase Flow in Pipe Cyclonic Separator,” Ph.D. thesis, Cranfield University, Cranfield, UK) obtaining root-mean-square errors around 13% between CFD and experimental data. An experimental setup, in which LCO data were acquired, was built in order to validate a CFD model that includes both phases entering to the GLCC. An average discrepancy below 6% was obtained by comparing simulations with experimental data. Once the model was validated, five geometrical variables were tested with CFD. The considered variables correspond to the inlet configuration (location and inclination angle), the effect of dual inlet, and nozzle geometry (diameter and area reduction). Based on the results, the best configuration corresponds to an angle of 27 deg, inlet location 10 cm above the center, a dual inlet with 20 cm of spacing between both legs, a nozzle of 3.5 cm of diameter, and a volute inlet of 15% of pipe area. The combination of these options in the same geometry reduced LCO by 98% with respect to the original case of the experimental setup. Finally, the swirling decay was studied with CFD showing that liquid has a greater impact than the gas flowrate.

Sensitivity Analysis of Domain Considerations for Numerical Simulations of Film Cooling

2010 ◽  
Author(s):  
Perry L. Johnson ◽  
Cuong Q. Nguyen ◽  
Son H. Ho ◽  
Jayanta S. Kapat
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Film Cooling ◽  
Stokes Equations ◽  
Computational Simulation ◽  
Grid Cell ◽  
Diameter Ratio ◽  
Design Matrix ◽  
Computational Domain ◽  
Fine Mesh

The majority of computational fluid dynamics studies for turbine film cooling have employed the Reynolds-Averaged Navier-Stokes equations with various turbulence modeling techniques to achieve closure, most notably the various two equation (k-ε or k-ω) models. For computational simulation of film cooling, modeling the entire testing domain with a row of multiple holes while sustaining a sufficiently fine mesh would demand a large number of grid cells and a hefty computational expense. A significant reduction in the computational domain can be and has been achieved without much harm to the overall accuracy of the film cooling prediction. The current study aimed to investigate the necessary domain parameters for reducing the grid cell count without significantly affecting the accuracy of the solution. The Box-Behnken design for response surface methodology was employed to determine the relative influence of each parameter on the cooling effectiveness prediction. The experimental design matrix was executed for multiple blowing ratios (0.5, 1.0, 2.0) to include the effects of the blowing ratio on the computational domain. The work was carried out using a three-dimensional computational fluid dynamics finite volume method with the RANS equations and k-ε turbulence model. A cylindrical film cooling hole with a pitch-to-diameter ratio of 3.0, a length-to-diameter ratio of 7.5, and an inclination angle of 35° was studied. The results are compared against existing data in the literature as well as in-house experimental data. The data from each case is compared in terms of spatially-averaged effectiveness. The modeled entrance length was found to be the most important parameter, with the mainflow height a distant second. The size of the modeled plenum was not found to exert any significant influence on the effectiveness results. Explanations are offered for notable trends in the data and conclusions are drawn concerning the grid optimization process.

scholarly journals Effects of cough-jet on airflow and contaminant transport in an airliner cabin section

2017 ◽  
Vol 10 (2) ◽  
pp. 72-82 ◽  
Author(s):  
Lin Yang ◽  
Xiangdong Li ◽  
Yihuan Yan ◽  
Jiyuan Tu
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Contaminant Transport ◽  
Air Flow ◽  
Numerical Results ◽  
Computational Domain ◽  
Short Period ◽  
Simulation Results ◽  
Precise Representation ◽  
Cabin Environment

The goals of this study were to investigate the effect of cough-jet on local airflow and contaminant transport in a typical cabin environment by using computational fluid dynamics. A fully occupied airliner cabin section was employed as the computational domain. Contaminants were released through coughing passengers from different locations inside the cabin. Numerical results in terms of contaminant transport characteristics were examined and compared. It can be concluded that cough-jet has significant effects on air flow in front of cough passenger in a short period of time. Also, it was found that, without considering the cough-jet model, the simulation results could not be a precise representation of the transport and distribution of cough-generated airborne contaminants.

Sign in / Sign up

Export Citation Format

Share Document