Now showing 1 - 10 of 10
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    Centrifugal impeller blade shape optimization through numerical modeling
    (01-10-2016)
    Bellary, Sayed Ahmed Imran
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    Surrogate model based shape optimization methodology to enhance performance of a centrifugal pump has been implemented in this work. Design variables, such as blade number and blade angles defining the pump impeller blade shape were selected and a three-level full factorial design approach was used for efficiency enhancement. A three-dimensional simulation using Reynolds-averaged Navier Stokes (RANS) equations for the performance analysis was carried out after designing the geometries of the impellers at the design points. Standard k-ε turbulence model was used for steady incompressible flow simulations. The optimized impeller incurred lower losses by shifting the trailing edge towards the impeller pressure side. It is observed that the surrogates are problem dependent and most accurate surrogate does not deliver the best design always.
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    Exit blade angle and roughness effect on centrifugal pump performance
    (01-01-2013)
    Bellary, Sayed Ahmed Imran
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    Exit blade angle and impeller surface roughness has a significant effect on the performance of a centrifugal pump impeller handling different viscosity fluids. In this paper, a three-dimensional flow simulation using Reynolds averaged Navier Stokes (RANS) equations for the performance analysis of the impeller is reported. The analysis using water and viscous liquids has been accomplished for different flow conditions, exit blade angle and roughness values. Standard k-ε two equation model is used for the turbulent closure of steady incompressible flow. The investigation shows that the blade exit angle has influence on the head, shaft power and efficiency of the impeller for different liquids. Rise in head, increase in shaft power and decrease in hydraulic efficiency have been observed with increasing roughness. Copyright © 2013 by ASME.
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    Experimental and Numerical Investigation of the Performance of a Centrifugal Pump When Pumping Water and Light Crude Oil
    (01-11-2017)
    Siddique, M. Hamid
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    Bellary, Sayed Ahmed Imran
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    Kim, Jin Hyuk
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    Choi, Young Seok
    In the oil and gas industry, crude oil is frequently transported and centrifugal pumps are used extensively. The pump impeller works under both design and off-design conditions in the applications, and the flow pattern deviates from the ideal case because of viscosity and density changes. An experimental as well as a numerical study was conducted to study the performance of a pump delivering water and light crude oil under design and off-design conditions. A 3D steady incompressible flow in the centrifugal pump was simulated by solving the Reynolds-averaged Navier–Stokes equations and SST turbulence model. At a low flow rate, extensive reverse flow occurs at the inlet of the impeller in the case of water, whereas the opposite was found for light crude oil. Recirculation was observed in the impeller flow passage for both water and the crude oil, but this diminished at higher flow rates.
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    Pumping crude oil by centrifugal impeller having different blade angles and surface roughness
    (01-03-2016)
    Bellary, Sayed Ahmed Imran
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    Centrifugal pumps are extensively used in the oil and gas industries and the pump performance drops with higher viscosity and higher surface roughness of the pump impeller, and the impeller design parameters have significant effect on the pump performance. Through the present research, crude oil pumping behavior has been predicted, analyzed and compared with other fluids. A 3D flow simulation using Reynolds-averaged Navier–Stokes (RANS) equation was performed by considering different blade angles and impeller surface roughness to pump crude oil, kerosene, gasoline, saline-water and water. Standard k-ε two-equation turbulence model was used for the turbulent closure of steady incompressible flow. The investigation shows that the blade angles have significant influence on the head, input power and efficiency of the impeller for different liquids. Higher head and power, and lower hydraulic efficiency were observed with higher surface roughness values.
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    Effectiveness of meta-models for multi-objective optimization of centrifugal impeller
    (01-12-2014)
    Bellary, Sayed Ahmed Imran
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    Husain, Afzal
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    The major issue of multiple fidelity based analysis and optimization of fluid machinery system depends upon the proper construction of low fidelity model or meta-model. A low fidelity model uses responses obtained from a high fidelity model, and the meta-model is then used to produce population of solutions required for evolutionary algorithm for multi-objective optimization. The Pareto-optimal front which shows functional relationships among the multiple objectives can produce erroneous results if the low fidelity models are not well-constructed. In the present research, response surface approximation and Kriging meta-models were evaluated for their effectiveness for the application in the turbomachinery design and optimization. A high fidelity model such as CFD technique along with the meta-models was used to obtain Pareto-optimal front via multi-objective genetic algorithm. A centrifugal impeller has been considered as case study to find relationship between two conflicting objectives, viz., hydraulic efficiency and head. Design variables from the impeller geometry have been chosen and the responses of the objective functions were evaluated through CFD analysis. The fidelity of each meta-model has been discussed in context of their predictions in entire design space in general and near optimal region in particular. Exploitation of the multiple meta-models enhances the quality of multi-objective optimization and provides the information pertaining to fidelity of optimization model. It was observed that the Kriging meta-model was better suited for this type of problem as it involved less approximation error in the Pareto-optimal front.
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    Application of computational fluid dynamics and surrogate-coupled evolutionary computing to enhance centrifugal-pump performance
    (01-01-2016)
    Bellary, Sayed Ahmed Imran
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    Adhav, Rohit
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    Siddique, M. Hamid
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    Chon, Bo Hyun
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    Kenyery, Frank
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    To reduce the total design and optimization time, numerical analysis with surrogate-based approaches is being used in turbomachinery optimization. In this work, multiple surrogates are coupled with an evolutionary genetic algorithm to find the Pareto optimal fronts (PoFs) of two centrifugal pumps with different specifications in order to enhance their performance. The two pumps were used a centrifugal pump commonly used in industry (Case I) and an electrical submersible pump used in the petroleum industry (Case II). The objectives are to enhance head and efficiency of the pumps at specific flow rates. Surrogates such as response surface approximation (RSA), Kriging (KRG), neural networks and weighted-average surrogates (WASs) were used to determine the PoFs. To obtain the objective functions' values and to understand the flow physics, Reynolds-averaged Navier-Stokes equations were solved. It is found that the WAS performs better for both the objectives than any other individual surrogate. The best individual surrogates or the best predicted error sum of squares (PRESS) surrogate (BPS) obtained from cross-validation (CV) error estimations produced better PoFs but was still unable to compete with the WAS. The high CV error-producing surrogate produced the worst PoFs. The performance improvement in this study is due to the change in flow pattern in the passage of the impeller of the pumps.
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    Numerical analysis of centrifugal impeller for different viscous liquids
    (26-12-2015)
    Bellary, Sayed Ahmed Imran
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    Oil and gas industry pumps viscous fluids and investigation of flow physics is important to understand the machine behavior to deliver such fluids. 3D numerical flow simulation and analysis for different viscous fluids at different rotational speeds of a centrifugal impeller have been reported in this paper. Reynolds-averaged Navier Stokes (RANS) equations were solved and the performance analysis was made. Standard two equation k-ε model was used for the turbulence closure of steady incompressible flow. An inlet recirculation and reverse flow in impeller passage was observed at low impeller speeds. It was also found that the higher viscosity fluids have higher recirculation which hinders the impeller performance.
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    A comparative study of kriging variants for the optimization of a turbomachinery system
    (01-01-2016)
    Bellary, Sayed Ahmed Imran
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    Couckuyt, Ivo
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    Dhaene, Tom
    Kriging is a well-established approximation technique for deterministic computer experiments. There are several Kriging variants and a comparative study is warranted to evaluate the different performance characteristics of the Kriging models in the computational fluid dynamics area, specifically in turbomachinery design where the most complex flow situations can be observed. Sufficiently accurate flow simulations can take a long time to converge. Hence, this type of simulation can benefit hugely from the computational cheap Kriging models to reduce the computational burden. The Kriging variants such as ordinary Kriging, universal Kriging and blind Kriging along with the commonly used response surface approximation (RSA) model were used to optimize the performance of a centrifugal impeller using CFD analysis. A Reynolds-averaged Navier–Stokes equation solver was utilized to compute the objective function responses. The responses along with the design variables were used to construct the Kriging variants and RSA functions. A hybrid genetic algorithm was used to find the optimal point in the design space. It was found that the best optimal design was produced by blind Kriging, while the RSA identified the worst optimal design. By changing the shape of the impeller, a reduction in inlet recirculation was observed, which resulted into an increase in efficiency.
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    Improvement of efficiency by design optimization of a centrifugal pump impeller
    (01-01-2014)
    Bellary, Sayed Ahmed Imran
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    Shape optimization of centrifugal impeller blades has been performed through numerical analysis and implementation of multiple surrogate based optimization methodology. Design variables which are used to define blade angles at leading and trailing edges were introduced to increase the hydraulic efficiency of the impeller. The efficiency was selected as an object function and the optimization was performed using a surrogate base optimization methods. A three-dimensional simulation using Reynolds-averaged Navier Stokes equations for the performance analysis was carried out after designing the geometries of the impellers at the design points selected from the design space which was defined by the lower and upper limits of the variables. Throughout the shape optimization, the hydraulic efficiency was increased by decreasing losses near the blade surfaces and impeller passage. Among different surrogates, a weighted average model produced better results. The application of the multiple surrogate methods not only improved quality of single objective optimization but also gives the feedback of the fidelity of the optimization models.
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    An alternative approach to surrogate averaging for a centrifugal impeller shape optimisation
    (01-01-2017)
    Bellary, Sayed Ahmed Imran
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    A major concern regarding surrogate model-based design optimisation is the modelling fidelity of the approximation functions. This issue is efficaciously addressed by utilising multiple surrogates based on the same data to offer approximations from alternative modelling perspective. The approach is introduced to optimise performance of a centrifugal impeller as a case study. The basic surrogate models adopted here include response surface approximation, radial basis neural network, Kriging, support vector machine and Shepard method. A weighted average and a new weighted average surrogate models were constructed from the basic surrogates and implemented in the present problem. A hybrid genetic algorithm was used to explore the optimal points. Design variables from the impeller inlet and exit blade angles were selected and design of experiments were used to select the sample points from the design space. The aim of the optimisation was to maximise hydraulic efficiency and head generated. The optimised centrifugal impeller yielded lower losses by altering the vane angles. It was found that the most accurate surrogate did not always lead to the best design. This manifested that using multiple surrogates can improve the robustness of the optimisation at a minimal computational cost.