Axial-Flow Ventilation Fan Design Through Multi-Objective Optimization to Enhance Aerodynamic Performance

2011 ◽  
Vol 133 (10) ◽  
Author(s):  
Jin-Hyuk Kim ◽  
Jae-Woo Kim ◽  
Kwang-Yong Kim
Keyword(s):  
Multiobjective Optimization ◽  
Axial Flow ◽  
Pressure Rise ◽  
Aerodynamic Performance ◽  
Low Flow ◽  
Total Efficiency ◽  
Objective Functions ◽  
Maximum Increase ◽  
Design Variables ◽  
Ventilation Fan

This paper presents an optimization procedure for axial-flow ventilation fan design through a hybrid multiobjective evolutionary algorithm (MOEA) coupled with a response surface approximation (RSA) surrogate model. Numerical analysis of a preliminary fan design is conducted by solving three-dimensional (3-D) Reynolds-averaged Navier-Stokes (RANS) equations with the shear stress transport (SST) turbulence model. The multiobjective optimization processes are performed twice to understand the coupled effects of diverse variables. The first multiobjective optimization process is conducted with three design variables defining stagger angles at the hub, mid-span, and tip, and the second is conducted with five design variables defining hub-to-tip ratio, hub cap installation distance, hub cap ratio, and the stagger angles at the mid-span and tip. Two aerodynamic performance parameters, the total efficiency and total pressure rise, are selected as the objective functions for optimization. These objective functions are numerically assessed through 3-D RANS analysis at design points sampled by Latin hypercube sampling in the design space. The optimization yields a maximum increase in efficiency of 1.8% and a 31.4% improvement in the pressure rise. The off-design performance is also improved in most of the optimum designs except in the region of low flow rate.

Aerodynamics of Contra-Rotating Fans With Swept Blades

2015 ◽  
Author(s):  
K. Vijayraj ◽  
M. Govardhan
Keyword(s):  
Rotational Speed ◽  
Axial Flow ◽  
Pressure Rise ◽  
Aerodynamic Performance ◽  
The Other ◽  
Flow Structures ◽  
Current Investigation ◽  
Rotating System ◽  
Stall Margin ◽  
Static Head

A Counter-Rotating System (CRS) is composed of a front rotor and a rear rotor which rotates in the opposite direction. Compared with traditional rotor-stator system, the rear rotor is used not only to recover the static head but also to supply energy to the fluid. Therefore, to achieve the same performance, the use of a CRS may lead to a reduction of the rotational speed and may generate better homogeneous flow downstream of the stage. On the other hand, the mixing area in between the two rotors induces complicated interacting flow structures. Blade sweep has attracted the turbomachinery blade designers owing to a variety of performance benefits it offers. However, the effect of blade sweep on the performance, stall margin improvements whether it is advantageous/disadvantageous to sweep one or both rotors has not been studied till now. In the current investigation blade sweep on the performance characteristics of contra rotating axial flow fans are studied. Two sweep schemes (axial sweeping and tip chord line sweeping) are studied for two sweep angles (20° and 30°). Effect of blade sweep on front rotor and rear rotor are dealt separately by sweeping one at a time. Both rotors are swept together and effect of such sweep scheme on the aerodynamic performance of the stage is also reported here. The performance of contra rotating fan is significantly affected by all these parameters. Blade sweep improved the pressure rise and stall margin of front rotors. Axially swept rotors are found to have higher pressure rise with reduced incidence losses near the tip for front rotors. Sweeping the rear rotor is not effective since the pressure rise is less than that of unswept rotor and also has less stall margin.

Influence of Blade Sweep on the Energetic Behavior of Axial Flow Turbomachinery Rotors at Design Flow Rate

2004 ◽  
Author(s):  
Ja´nos Vad ◽  
Ali R. A. Kwedikha ◽  
Helmut Jaberg
Keyword(s):  
Aspect Ratio ◽  
Flow Rate ◽  
Axial Flow ◽  
Pressure Rise ◽  
Design Flow ◽  
Tip Clearance ◽  
Total Efficiency ◽  
Low Aspect Ratio ◽  
Axial Velocity Profile ◽  
Bladed Rotor

Experimental and computational studies were carried out in order to survey the energetic aspects of forward and backward sweep in axial flow rotors of low aspect ratio blading for incompressible flow. It has been pointed out that negative sweep tends to increase the lift, the flow rate and the ideal total pressure rise in the vicinity of the endwalls. Just the opposite tendency was experienced for positive sweep. The local losses were found to develop according to combined effects of sweep near the endwalls, endwall and tip clearance losses, and profile drag influenced by re-arrangement of the axial velocity profile. The forward-swept bladed rotor showed reduced total efficiency compared to the unswept and swept-back bladed rotors. This behavior has been explained on the basis of analysis of flow details. It has been found that the swept bladings of low aspect ratio tend to retain the performance of the unswept datum rotor even in absence of sweep correction.

Effect of Axial Sweep and Tip Extension on Performance of an Axial Fan

2016 ◽  
Author(s):  
Ankit Bhai Patel ◽  
K. Viswanath ◽  
Dhyanjyoti Deb Nath
Keyword(s):  
Performance Improvement ◽  
Flow Direction ◽  
Pressure Rise ◽  
Aerodynamic Performance ◽  
Secondary Flows ◽  
Tip Vortex ◽  
Low Flow ◽  
Pressure Probe ◽  
Axial Fan ◽  
Stall Margin

Performance enhancement in terms of stall margin increment, increased pressure rise coefficient and increased efficiency is of great need for low speed axial fans. Stacking line modifications in terms of sweep, skew, dihedral or combination of these, as well as blade tip geometry modifications are assumed to be one of the ways to achieve finite performance improvement. Non radial stacking of blade profiles modifies secondary flows, tip vortex effects, hub passage vortex and thus affects aerodynamic performance parameters such as stall margin, efficiency, pressure rise, blade loading. In literature many studies have confined to comparison of few cases which led to conflicting results as modification of stacking line may have different effects in different cases. In the present work, comparison of performance of axial fan rotor with three different blade configurations BSL (baseline), SWP (swept blade) and EXTN (swept blade with extended tip) are considered. The BSL configuration is designed on basis of non-free vortex design. The SWP configuration is obtained by shifting radial stacking line of the BSL in axial flow direction by 10° (Forward sweep). The EXTN configuration is obtained by extending tip profile on pressure surface as well as suction surface by 3% locally. Experiments have been conducted on these three configurations to study effects of these modifications on aerodynamic performance. The flow field has been surveyed using Kiel probe, Three hole pressure probe at many flow rates starting from fully open to fully closed. Unsteady flow analysis at exit of rotors of all configurations is carried out using fast response pressure probe. Experimental results show slight performance improvement in terms of increased stall margin, efficiency, as well as total pressure rise for SWP rotor as well as EXTN rotor compared to BSL rotor at low flow coefficients.

Multiobjective Optimization of a Microchannel Heat Sink Using Evolutionary Algorithm

2008 ◽  
Vol 130 (11) ◽  
Author(s):  
Afzal Husain ◽  
Kwang-Yong Kim
Keyword(s):  
Multiobjective Optimization ◽  
Evolutionary Algorithm ◽  
Performance Optimization ◽  
Heat Sink ◽  
Algorithm Design ◽  
Pareto Optimal ◽  
Microchannel Heat Sink ◽  
Objective Functions ◽  
Design Variables ◽  
Polynomial Response Surface

A multiobjective performance optimization of microchannel heat sink is carried out numerically applying surrogate analysis and evolutionary algorithm. Design variables related to microchannel width, depth, and fin width are selected, and two objective functions, thermal resistance and pumping power, are employed. With the help of finite volume solver, Navier–Stokes analyses are performed at the design sites obtained from full factorial design of sampling methods. Using the numerically evaluated objective function values, polynomial response surface is constructed for each objective functions, and multiobjective optimization is performed to obtain global Pareto optimal solutions. Analysis of optimum solutions is simplified by carrying out trade-off with design variables and objective functions. Objective functions exhibit changing sensitivity to design variables along the Pareto optimal front.

scholarly journals Application of data mining in multiobjective optimization problems

2014 ◽  
Vol 5 ◽  
pp. A15 ◽  
Author(s):  
Amir Mosavi
Keyword(s):  
Data Mining ◽  
Multiobjective Optimization ◽  
Optimization Design ◽  
Optimization Problems ◽  
Objective Functions ◽  
Design Variables ◽  
Modeling Techniques ◽  
Practical Engineering ◽  
Meta Modeling ◽  
Classification Tool

In the most engineering optimization design problems, the value of objective functions is not clearly defined in terms of design variables. Instead it is obtained by some numerical analysis such as FE structural analysis, fluid mechanic analysis, and thermodynamic analysis, etc. Usually, these analyses are considerably time consuming to obtain a value of objective functions. In order to make the number of analyses as few as possible a methodology is presented as a supporting tool for the meta-modeling techniques. Researches in meta-modeling for multiobjective optimization are relatively young and there is still much to do. It is shown that visualizing the problem on the basis of the randomly sampled geometrical data of CAD and CAE simulation results, in addition to utilizing classification tool of data mining could be effective as a supporting system to the available meta-modeling techniques. To evaluate the effectiveness of the proposed method a study case in 3D wing design is given. Along with this example, it is discussed how effective the proposed methodology could be in the practical engineering problems.

scholarly journals Design and Performance Analysis of Blades Based on the Equal–Variable Circulation Method

2021 ◽  
Vol 9 ◽  
Author(s):  
D. Liang ◽  
C. Song ◽  
S. Liang ◽  
S. Wang ◽  
Y. Li ◽  
...  
Keyword(s):  
Design Method ◽  
Axial Flow ◽  
Aerodynamic Performance ◽  
Low Flow ◽  
Improve Performance ◽  
Flow Rates ◽  
Circulation Method ◽  
Blade Tip ◽  
New Type ◽  
And Performance

With the aim of improving the aerodynamic performance of axial turbomachinery, a new type of blade is designed using the equal–variable circulation method. Taking an axial flow fan as the research object, this article describes the development of a new type of turbomachinery by changing the design method and producing a blade with forward sweep. The aerodynamic performance of the fan is simulated and compared with the experimental data. The numerical results show that the equal circulation design method improves the aerodynamic performance of the blade roots, while the variable circulation design method enhances the aerodynamic performance of the blade tips. By adopting the equal–variable circulation design method, the total pressure of the experimental fan is increased by about 4%, while the efficiency remains unchanged. Forward-swept blades with an equal–variable circulation design also improve performance over the conventional blades by changing the center-of-gravity stacking line. At low flow rates, the efficiency of the experimental fan can be increased by 7.5%, and the working range of the flow is expanded. Under high flow rates, the restriction of the blade tip on the airflow is decreased and the fluidity is slightly reduced.

Multi-Objective Shape Optimization on the Inlet Pipe of a Vertical Inline Pump

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Ji Pei ◽  
Xingcheng Gan ◽  
Wenjie Wang ◽  
Shouqi Yuan ◽  
Yajing Tang
Keyword(s):  
Genetic Algorithm ◽  
Cross Sections ◽  
Great Influence ◽  
Latin Hypercube Sampling ◽  
Installation Space ◽  
Objective Functions ◽  
Inlet Pipe ◽  
Maximum Increase ◽  
Multi Objective ◽  
Design Variables

Vertical inline pump is a single-stage single-suction centrifugal pump with a bent pipe before the impeller, which is usually used where installation space is a constraint. In this paper, with three objective functions of efficiencies at 0.5 Qd, 1.0 Qd, and 1.5 Qd, a multi-objective optimization on the inlet pipe of a vertical inline pump was proposed based on genetic algorithm with artificial neural network (ANN). In order to describe the shape of inlet pipe, the fifth-order and third-order Bezier curves were adopted to fit the mid curve and the trend of parameters of cross sections, respectively. Considering the real installation and computation complexity, 11 variables were finally used in this optimization. Latin hypercube sampling (LHS) was adopted to generate 149 sample cases, which were solved by CFD code ANSYS cfx 18.0. The calculation results and design variables were utilized to train ANNs, and these surrogate models were solved for the optimum design using multi-objective genetic algorithm (MOGA). The results showed the following: (1) There was a great agreement between numerical results and experimental results; (2) The ANNs could accurately fit the objective functions and variables. The maximum deviations of efficiencies at 0.5 Qd, 1.0 Qd, and 1.5 Qd, between predicted values and computational values, were 1.94%, 2.35%, and 0.40%; (3) The shape of inlet pipe has great influence on the efficiency at part-load and design conditions while the influence is slight at overload condition; (4) Three optimized cases were selected and the maximum increase of the efficiency at 0.5 Qd, 1.0 Qd, and 1.5 Qd was 4.96%, 2.45, and 0.79%, respectively; and (5) The velocity distributions of outflow in the inlet pipe of the three optimized cases were more uniform than the original one.

Inlet Box Structure Optimization of a Large Axial-Flow Fan Using Response Surface Methodology

2020 ◽  
Author(s):  
Jin Xiong ◽  
Yinkun Zhang ◽  
Penghua Guo ◽  
Jingyin Li
Keyword(s):  
Total Pressure ◽  
Design Method ◽  
Orthogonal Design ◽  
Axial Flow ◽  
Pressure Rise ◽  
Aerodynamic Performance ◽  
Design System ◽  
Orthogonal Design Method ◽  
Box Structure ◽  
Inlet Box

Abstract Large axial-flow fans are widely used in many fields. The inlet box is an integral part of large axial-flow fans, and a well-designed inlet box could effectively improve fan efficiency. However, the inlet box structure is complicated, and the existing inlet box design method severely depends on the design experience. In this study, we propose a structure optimization design system based on a surrogate model technique for researching the critical structure parameters of the inlet box and accomplishing aerodynamic performance optimization. As for this expensive optimization problem, the design system contains twice optimization procedures by using the Response Surface Methodology (RSM) with the orthogonal design method. The optimization object is an existing large axial-flow fan. The optimization objective is the total pressure efficiency of the fan, and the total pressure rise is the restriction condition. We generate eighteen different inlet boxes connect with the same impeller and outlet pipe by the orthogonal design method and calculated fan aerodynamic performance by CFX software. After the first optimization, we find the key structural parameters by the sensitivity analysis and the reselect variables total of 25 cases are adopted in a further RSM optimal process. The ultimate surrogate model estimates the fan with the optimal inlet box has a better aerodynamic characteristic and a 6.7% total pressure efficiency rise. Finally, we compare the aerodynamic characteristics of the ultimate design fan and the initial fan by CFD simulation. The numerical results show that: the total pressure efficiency is 6.5% higher than that of the initial impeller, and the pressure rise is 3% higher than that of the initial impeller. The result demonstrates that some most critical parameters of the inlet box structure decide the aerodynamic performance, and the inlet box optimization effectively increases the fan efficiency in the meanwhile.

Optimal Stochastic Design of Four-Bar Mechanisms for Tolerance and Clearance

1988 ◽  
Vol 110 (3) ◽  
pp. 255-262 ◽  
Author(s):  
Je Ha Rhyu ◽  
Byung Man Kwak
Keyword(s):  
Multiobjective Optimization ◽  
Stochastic Model ◽  
Optimization Problem ◽  
Manufacturing Cost ◽  
Multiobjective Optimization Problem ◽  
Objective Functions ◽  
Function Generator ◽  
Weighting Method ◽  
Design Variables ◽  
Four Bar Linkage

A formulation of optimal stochastic design of mechanisms considering tolerances on the link lengths and clearances in the joints is presented. The mechanical error is analyzed for the 3σ band of confidence level through a new stochastic model of a four-bar linkage. A multiobjective optimization problem with two objective functions, mechanical error and manufacturing cost, is considered by a weighting method. Tolerance widths and nominal clearance sizes are taken as design variables. The conflicting nature between the two objectives is represented in the form of tradeoff curves. A concept of loop closure error is also introduced and applied to optimum design of the nominal linkage system and the stochastic linkage system. Numerical results are given for a four-bar function generator and a four-bar path generator.

Multi-Objective Design Problem of Tire Wear and Visualization of Its Pareto Solutions2

2006 ◽  
Vol 34 (3) ◽  
pp. 170-194 ◽  
Author(s):  
M. Koishi ◽  
Z. Shida
Keyword(s):  
Inverse Problems ◽  
Conceptual Design ◽  
Dimensional Space ◽  
Design Stage ◽  
Objective Functions ◽  
Pareto Solutions ◽  
Design Problems ◽  
Multi Objective ◽  
Design Engineers ◽  
Design Variables

Abstract Since tires carry out many functions and many of them have tradeoffs, it is important to find the combination of design variables that satisfy well-balanced performance in conceptual design stage. To find a good design of tires is to solve the multi-objective design problems, i.e., inverse problems. However, due to the lack of suitable solution techniques, such problems are converted into a single-objective optimization problem before being solved. Therefore, it is difficult to find the Pareto solutions of multi-objective design problems of tires. Recently, multi-objective evolutionary algorithms have become popular in many fields to find the Pareto solutions. In this paper, we propose a design procedure to solve multi-objective design problems as the comprehensive solver of inverse problems. At first, a multi-objective genetic algorithm (MOGA) is employed to find the Pareto solutions of tire performance, which are in multi-dimensional space of objective functions. Response surface method is also used to evaluate objective functions in the optimization process and can reduce CPU time dramatically. In addition, a self-organizing map (SOM) proposed by Kohonen is used to map Pareto solutions from high-dimensional objective space onto two-dimensional space. Using SOM, design engineers see easily the Pareto solutions of tire performance and can find suitable design plans. The SOM can be considered as an inverse function that defines the relation between Pareto solutions and design variables. To demonstrate the procedure, tire tread design is conducted. The objective of design is to improve uneven wear and wear life for both the front tire and the rear tire of a passenger car. Wear performance is evaluated by finite element analysis (FEA). Response surface is obtained by the design of experiments and FEA. Using both MOGA and SOM, we obtain a map of Pareto solutions. We can find suitable design plans that satisfy well-balanced performance on the map called “multi-performance map.” It helps tire design engineers to make their decision in conceptual design stage.

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