Impeller Design Research Articles

Lightweight design and static analysis of lattice compressor impeller

Taking the compressor impeller as the research object and the lightweight design as the research goal, a lattice filled lattice cell suitable for the application of rotating periodic symmetric structure is designed. Its purpose is to make the rigidity and strength of impeller adjustable and reduce the mass of impeller on the premise of meeting the design requirements. The analysis and comparison of unfilled impeller, solid impeller and lattice filled impeller with different diameters were carried out under the limit condition of 80,000 r/min. The results showed that the average circumferential deformation of lattice impeller tip with beam diameter of 0.2 mm, 0.4 mm and 1 mm was 4.84%, 3.49% and 3.71% lower than that of solid impeller. For the impeller with a lattice beam diameter of 0.4 mm, its weight can be reduced by 22.68% compared with the solid impeller. The average circumferential deformation of the tip of the lattice impeller lies between the unfilled impeller and the solid impeller. The results show that the impeller with lattice filling hub can not only reduce the weight effectively, but also improve the efficiency of the compressor.

Impeller shape-optimization of stirred-tank reactor: CFD and fluid structure interaction analyses

Mixing is an important operation in the chemical industry. The present numerical study, validated by experimental data, offers a computational framework for minimizing the stirred-tank reactor power consumption and the impeller equivalent stress. The flow pattern, turbulence parameters, and power consumption of the three types of impellers, named as 6-blade Rushton turbine and U-shape and V-shape impeller designs, are numerically studied using the Computational Fluid Dynamic (CFD) analysis. The interaction between the fluid and the solid is then studied through a two-way Fluid Structural/Solid Interaction (FSI) analysis. Multi-objective Genetic Algorithm (MOGA) is used along with both Direct Optimization (DO) and Response Surface Optimization (RSO) to optimize the blade’s geometrical parameters, including blade thickness (Tb), disk thickness (TD), and vertical angle of the blade (θ). The variation between experimental and numerical results, in terms of power consumption, is around 5%. The computational results show that the power number (Np) can decrease, respectively by 21% and 48%, for the V- and U-shape impellers compared to the 6-blade Rushton turbine. The maximum turbulent kinetic energy and the maximum dissipation rate of the turbulent kinetic energy of the U-shape (k = 0.065 m2/s2, ε = 65.14 m2/s3) are more than V-shape impeller (k = 0.044 m2/s2, ε = 25.16 m2/s3). The FSI results also show that the lowest von Mises stress occurs in the V-shape impeller.

Simulation of Mixing Intensity Profile for Bioethanol Production via Two-Step Fermentation in an Unbaffled Agitator Reactor

Bioethanol synthesis techniques have been studied intensively due to the energy crisis and various environmental concerns. A two-step bioethanol production process was carried out multiple times in an unbaffled agitator tank. The parameters varied, including the fermentation temperature, the pH level, the amount of yeast, and the impeller type. Then, a simulation was used to obtain an image of the agitation behavior inside the agitator tank to compare the velocity profile of each type of impeller design. The impeller with eight blades was found to produce the highest flow velocity: 0.28 m/s. The highest concentration of bioethanol generated from the fermentation was 34 g/L, which was produced by using an eight-blade impeller at 30 °C, a pH level of 5, an agitation speed of 70 rpm, and 2 wt % yeast. The two-blade impeller produced the lowest bioethanol concentration, 18 g/L, under the same conditions. Ethanol concentration was found to peak at 40 °C and a pH level of 5. The geometry of the impeller, the fermentation temperature, and the pH level were each found to have a significant effect on the resulting bioethanol concentration according to the results of an ANOVA test. The amount of yeast had no effect on the fermentation reaction. Finally, the results demonstrated the possibility of using computational fluid dynamic modeling to determine the impeller’s behavior for the development of the bioethanol fermentation process. The simulation and experimental results from this research support the scaling up of a bioethanol production facility.

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

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.

Optimization of thermosolutal convection in vertical porous annulus with a circular baffle

An enclosed annular geometry with a conducting baffle attached to one of the thermally active walls aptly represents many scientific applications. This article reports the thermosolutal convection in a vertical cylindrical porous annulus with a thin baffle attached to an inner cylinder. The vertical left and right walls of the annular space are differently heated, whereas the top and bottom walls are thermally insulated. A finite difference method based numerical technique has been adapted to solve the governing model equations. Numerical simulations are carried out for various parameter ranges in the interest of capturing the influence of thermal Rayleigh, Darcy and Lewis numbers, buoyancy ratio, baffle length and location on flow pattern, heat and mass transport. From the numerical results it is found that, the heat and mass transport can be effectively enhanced or suppressed by the appropriate choices of baffle length and location. In particular, the thermal and solute transport rates are suppressed with the length of baffle. However, transport rates can be enhanced by positioning the baffle towards top adiabatic wall. Numerical predictions made in this analysis can be utilized for the design of heat exchangers and chemical impellers.

Improvement of Internal Flow Performance of a Centrifugal Pump-As-Turbine (PAT) by Impeller Geometric Optimization

Rotor-stator interaction (RSI) in the centrifugal pump-as-turbine (PAT) is a significant source of high amplitude of the pressure pulsation and the flow-induced vibration, which is detrimental to the stable operation of PAT. It is therefore imperative to analyze the rotor-stator interaction, which can subsequently be used as a guideline for reducing the output of PAT noise, vibration and cavitation. In addition, it is important for a PAT to have a wide operating range preferably at maximum efficiency. In order to broaden the operating range, this work proposes a multi-condition optimization scheme based on numerical simulations to improve the performance of a centrifugal PAT. In this paper, the optimization of PAT impeller design variables (b2, β1, β2 and z) was investigated to shed light upon its influence on the output efficiency and its internal flow characteristics. Thus, the aim of the study is to examine the unsteady pressure pulsation distributions within the PAT flow zones as a result of the impeller geometric optimization. The numerical results of the baseline model are validated by the experimental test for numerical accuracy of the PAT. The optimized efficiencies based on three operating conditions (1.0Qd, 1.2Qd, and 1.4Qd) were maximally increased by 13.1%, 8.67% and 10.62%, respectively. The numerical results show that for the distribution of PAT pressure pulsations, the RSI is the main controlling factor where the dominant frequencies were the blade passing frequency (BPF) and its harmonics. In addition, among the three selected optimum cases, the optimized case C model exhibited the highest level of pressure pulsation amplitudes, while optimized case B reported the lowest level of pressure pulsation.

CFD numerical simulation of particle suspension and hydromechanical stress in various designs of multi-stage bioleaching reactors

The performance of bioleaching stirred tank reactors (STR) is related to the homogeneity of biomass, substrates and dissolved gases. This work was focused on the characterization of the impeller design on bioreactor hydrodynamics and, more specifically on power, mixing efficiency and particle stress. Few studies addressed the issue of the impact of the impeller design on these, especially for multi-stage bioreactors which are the most commonly used at the industrial scale. To fill this lack, a two-stage solid-liquid computational fluid dynamics (CFD) model was simulated on more than 50 conditions to assess power consumption, dissipated power, suspension quality and particle stress. A dual impeller configuration was chosen using Rushton turbines, R600, Hydrofoil, Elephant Ear and HTPG impellers. Grinded pyrite-rich materials (average particles size: 80 μm) were considered as the solid phase at 3 different solid concentrations (10, 18 and 26% w/w). Considering the impeller power number (Np), the configuration with an axial impeller consumed less energy than a radial impeller in concordance with literature data. The results show that the impeller design had few to no effect on mixing efficiency considering a given power dissipation per unit volume. Independently on the impeller used, unique relationships were found between particle stress and mixing efficiency. This study gives new insights for reactor design and scaling of bioleaching stirred tank reactor and more specifically on the reduction of shear stress for the attached bacterial communities.

Tesla Bladed Pump (Disc Bladed Pump) Preliminary Experimental Performance Analysis

A preliminary experimental work on a centrifugal pump model specifically designed to transport slurry and multiphase flows is presented. The impeller design corresponds to the so-called “Tesla Bladed Pump” adapted from an existing DiscflowTM pump design for the petroleum deep-sea application. The overall performance results of such a specific pump design are presented for different rotational speeds and discussed in relation to affinity laws coefficients. The results show that the performance of the tested disc pump strongly differs from the conventional centrifugal bladed pump. A one-dimensional approach using complete Euler relation is used to explain the differences in the present case. Moreover, it has been found that available results in open literatures do not correspond to the real optimum conditions, more detailed research work must be performed to get a better understanding on this kind of bladed disc pump.

Impeller design and CFD analysis of fluid flow in rotodynamic pumps

The intricate internal flows in the rotodynamic water pump impellers can be well predicted by using computational fluid dynamics and mathematical modeling. An impeller is a radial type rotor that increases the acceleration of the fluid due to the centrifugal action and the fluid is pumped through the casing to a higher potential head. The efficiency and performance of the centrifugal pump can be enhanced by optimizing certain design parameters of the impeller. In this work, the impeller design and development of potential flow calculations for the liquid flow using the MATLAB software was performed. NX-CAD was used to model the impeller and pump. CFD analysis in ANSYS CFX showed the flow of liquid through the variable cross-section of the volute casing of the pump. Modification in impeller design showed that the overall performance of the pump can be improved. The program developed in the MATLAB also served as a type of calculator for determining the type of pump that can be used for various industrial purposes based on the velocity of the liquid, head and discharge rate.

Effect of crystallizer design and operational parameters on the batch crystallization of ibuprofen I: experimental

ABSTRACT Ibuprofen is widely used as an anti-inflammatory drug. Ibuprofen crystallized from non-polar hexane exhibits needle morphology, while from polar solvents, it exhibits a plate or polyhedral morphology. Among these, needle morphology possesses poor flow properties and poses difficulty in downstream processing. The flow properties (indicated by the bulk density) can be improved by manipulating heating–cooling cycles, hydrodynamics in the crystallizer, and seeding. In the present work, experiments were carried out to investigate the effect of various design and operating parameters such as impeller design, impeller speed, seed size, % seed quantity, and cooling profiles on ibuprofen crystal characteristics using hexane as a solvent. Closed clear impellers, such as helical ribbon impeller exhibits higher bulk density and average crystal size compared to open type impellers. Beyond certain agitation speeds, the average crystal size is affected by the breakage mechanism. The seed size and seed quantity showed a minor impact on bulk density and average crystal size.

Multi-Condition Optimization of Cavitation Performance on a Double-Suction Centrifugal Pump Based on ANN and NSGA-II

Double-suction centrifugal pumps form an integral part of power plant systems in maintaining operational stability. However, there has been a common problem of achieving a better cavitation performance over a wider operating range because the traditional approach for impeller design often leads to the design effect not meeting the operational needs at off-design conditions. In addressing the problem, an optimization scheme was designed with the hub and shroud inlet angles of the double-suction impeller to minimize the suction performance at non-design flow conditions. A practical approach that speeds up the cavitation simulation process was applied to solve the experimental design, and a multi-layer feed forward artificial neural network (ANN) was combined with the non-dominated sorting genetic algorithm II to solve the multi-objective problem into three-dimensional (3D) Pareto optimal solutions that meet the optimization objective. At the design point, the suction performance was improved by 6.9%. At non-design flow conditions, the cavitation performance was improved by 3.5% at 1.2Qd overload condition, 4% at 0.8Qd, and 5% at 0.6Qd. Additionally, there was significant reduction in the attached cavity distribution in the impeller and suction domains when the optimized model was compared to the original model at off-design points. Finally, the optimization established a faster method for a three-objective optimization of cavitation performance using ANN and 3D Pareto solutions.

Design of a transonic centrifugal compressor for High-speed turbomachinery

The paper presents a design of a small-scale centrifugal compressor to match the performance of up to 20% larger diameter compressor in order to meet the demands for a higher mass flow rate and wide operating range for turbocharging applications. This development considers the 44 mm diameter impeller design involving transonic blading and state-of-the-art blade features. In the course of design, the investigation on the inducer blade angle [Formula: see text] and blade inducer-to-outlet radius ratio has shown to have a dominant influence on the magnitude of inlet relative Mach number. Diffuser width and volute A/R ratio are also observed to be parameters affecting the overall performance of the compressor stage. Based on the diffuser parametric study, the most efficient diffuser width equal to 70% of the blade exducer width is observed. The performance of the present compressor stage is analyzed with computational fluid dynamics simulations and experimental tests. The comparison of the predicted and measured results of the 44 mm compressor stage shows a good agreement for overall performance. Besides, the 44 mm compressor stage having the most efficient diffuser width and enlarged volute A/R ratio shows a good overlap of performance with approximately 20% larger diameter (52 mm) compressor stage performance. This development demonstrates that the impeller with state-of-the-art design features are likely to contribute to enhancement of the compressor performance.

Vibration characteristic simulation and finite elementAnalysis of vehicle compressor impeller based on ANSYS

The vehicle compressor impeller of the turbocharger of the vehicle is often damaged by the vibration. Model analysis for the compressor impeller is a kind of common means to avoid resonance between the impeller and natural frequency. Based on the software of ANSYS, the mid and low order nature frequency of vehicle compressor impellerwas simulated and calculated by the method of submodel, and Campbell chart was drawn according to the results. The resonance speed of the nature frequency of compressor impeller was found, thus reference for optimal design of the compressor impeller was provided.

Performance improvement of mixed-flow centrifugal pumps with new impeller shrouds: Numerical and experimental investigations

A new impeller configuration with innovatively-designed shrouds is introduced, and its impact on the pressure head and efficiency of the semi-open centrifugal pump is explored using experimental and numerical approaches. The proposed design includes attaching specific plates called bladelets to a semi-open impeller to limit the secondary flows over the blades resulting in an increase in the pump head and efficiency. Hydraulic performance of a centrifugal pump with three different bladelets at angles of 30°, 60°, and 90° is investigated experimentally, and the results are compared to semi-open and closed impellers. The values of pressure head and efficiency of the proposed centrifugal pump are determined through numerical analysis and then compared to the experimental data in which an acceptable agreement between the results is observed. Both numerical and experimental results show the proposed impeller design promisingly improves the pressure head and efficiency of semi-open centrifugal pumps. Additionally, the flow analysis demonstrates that the impellers with 90° bladelets enhance the hydraulic performance of a semi-open centrifugal pump nearly to a closed impeller configuration. The loss reduction due to the secondary flow and the eddy generation leads to an improvement in the hydraulic performance of the proposed design.

A Deep Insight Into the Transonic Flow of an Advanced Centrifugal Compressor Design

Abstract In the last decades, major improvements in transonic centrifugal compressor design have been achieved. The further exploration of design space is enabled by recent progress in structural mechanics and manufacturing. A challenging task of inducer design especially in terms of transonic inflow conditions is to provide a wide flow range and reduced losses due to a sufficient shock control. The use of so-called multidisciplinary design optimization with an extensive amount of free parameters leads finally to complex designs. DLR’s latest fast rotating centrifugal compressor (SRV5) operates at a design speed of Mu2 = 1.72 and a total pressure ratio of 5.72. This compressor design is characterized by an S-shaped leading edge and free-form blade surfaces. Due to the complex design, the key design features are difficult to explore. Therefore, nonintrusive measurements are conducted on the highly loaded SRV5. The laser-2-focus (L2F) approach that is used in addition with the doppler-global-velocimetry (DGV) delivers a three-dimensional velocity field. Besides the impeller inflow, the outflow is also part of the experimental and numerical verification of the advanced compressor design. Experimental results are compared with the numerical analysis of the compressor using DLR’s Reynolds-averaged Navier–Stokes Flow Solver TRACE. The deep insight of the inflow leads to a better understanding of the operating behavior of such impeller designs.

Use of Gas Helicity as an Indicator to Evaluate Impeller Design and its Gas Holdup: Proof of Concept for the Intensification of Gas-Liquid Mixing

The fundamental insights into the impact of impeller geometry on the gas helicity can help equipment suppliers to design more energy-efficient impellers while reducing the overall energy expenses of wastewater plants and aerobic fermenter. In this perspective, the proof of concept was developed using electrical resistance tomography and computational fluid dynamics (CFD) modelling. At a fixed speed ratio (central impeller rotational speed/ anchor rotational speed), the sign of gas helicity (+ or -) provides insights about the gas velocity direction and the degree of gas holdup in non-Newtonian fluid. The predicted gas holdup was within the range of experimental measurement. In this experiment, the carboxymethyl cellulose (1 wt% CMC) solution was used. It is a non-Newtonian fluid which obeys the power law model. The ASI impeller was the most energy-efficient impeller which generate reasonable aeration efficiency with negative helicity. The poor aeration efficiency of some novel impellers such as ASI Slanted and PBT Up-Down were attributed to the fluctuations in the gas helicity sign. The proof of concept shows that the local helicity analysis can be insightful to better understand gas-liquid mixing and further intensify gas dispersion. The lift force generated by these impellers can be useful for anaerobic digester.

Design of an impeller for a fire fighting pump

The article presents the design of a single-stage centrifugal pump impeller for use in a fire vehicle. For such a task, the set utility parameters were determined, and then several methods were used to determine the geometry and dimensions of a given impeller. The project uses A. Stepanoff’s formulas, correction of power consumption reduction (Pfleiderer coefficient), as well as the method of point selection of the width of the impeller cross-section in relation to the changing radius of the impeller. A graphical representation of the pump flow rate and pump head depending on the type of impeller and the pump characteristic speed has enabled convenient analysis in terms of assumed pump performance. The procedure adopted in the project did not require the use of advanced engineering tools. The obtained result in the form of geometry and dimensions of the designed result coincides with the parameters of the impellers used in fire pumps currently in use. In the last step of the project, a three-dimensional impeller model was developed, which is a good starting point for optimization by simulation and then experimental verification on a real object.

Collaborative Design of the Wrap Angles Between Impeller and Space Diffuser of Diagonal-Flow Pump

The wrap angle is one of the key parameters in design of impeller and space diffuser. At present, it is mainly designed based on theoretical estimation and experience. However, there are few studies on collaborative design. In this paper, the process model of collaborative design was put forward, then 25 kinds of wrap angle matching schemes between impeller and space diffuser were determined by orthogonal experimental method, and it was completed to study basic change law of the external characteristics and flow field under different matching schemes. It was shown that impeller wrap angle had more obvious influence on the hydraulic characteristics than space diffuser wrap angle within a certain wrap angle range. Therefore, the optimal impeller wrap angle should be determined in the collaborative design at first. By the multidimensional evaluation criteria, it was carried out such as the selection of the space diffuser wrap angle. It can reduce a lot of work to easily find a better balance about multi-influence of the multi-component parameters, and get an optimal performance when the diagonal-flow pump is used in oil and gas development.

Fluid dynamics characterization and thrombogenicity assessment of a levitating centrifugal pump with different impeller designs

Technical guidelines nowadays recommend and regulate the use Computational Fluid Dynamics (CFD) to assess the performance of medical devices. CFD coupled to blood damage models has emerged as a powerful tool to evaluate the hemocompatibility of blood recirculating devices. The present study is aimed at evaluating the hydrodynamic performance and the thrombogenic potential of two prototypes of magnetically levitating centrifugal pumps. The two devices differ in the impeller configuration - 6-blades vs. 12-blades – and have been designed to be used in Cardiopulmonary Bypass (CPB) circuits during open heart surgery and in Extracorporeal Membrane Oxygenation (ECMO) to support patients with severe cardiac or respiratory failure. The pumps have been modelled using Direct Numerical Simulation coupled to Lagrangian analysis to predict platelet activation due to abnormal shear stress histories. Numerical results have been compared with experimental data in terms of head generation for different working points. Results show that the 6-blades pump has i) smaller stagnation areas, ii) lower stress levels and iii) higher strain rate, resulting in a lower thrombogenic potential, whereas the 12-blade impeller guarantees a more stable performance at high flow rates, suggesting its preferential use for more demanding applications, such as CPB.

The effect of impeller-stator design on bubble size: Implications for froth stability and flotation performance

The impeller in a mechanical flotation tank plays a key role in keeping particles in suspension, dispersing and breaking-up air bubbles, and promoting particle-bubble collision. However, the turbulent regime generated by the impeller can also affect the pulp-froth interface, destabilising the lower regions of the froth and affecting the overall flotation performance. The effects that pulp zone design modifications have on the froth are, however, poorly understood and have not been well-studied.In this work, we study the impact of impeller-stator design on the performance of a large laboratory-scale flotation tank. Two different impeller designs, with and without a stator, were assessed under a range of air flow rates to determine changes in pulp bubble size, froth stability, and metallurgical recovery. The results allow us to quantify, for the first time, the reduction in bubble size in a three-phase flotation system and the improvement in froth stability due to the use of a stator, and thus the enhancement in flotation performance. An inverse relationship is found between the pulp bubble size and froth stability. It is shown that the impeller designs that exhibited smaller bubble sizes resulted in higher froth stability values and also higher flotation recoveries. These findings provide insights into the links between pulp and froth zone phenomena, paving the way for improvements in flotation tank design that lead towards flotation optimisation.