Disk Impeller Research Articles

Influence of the centrifugal pump impeller vanes parameters on its energy performance at operating with high-viscosity liquid

BACKGROUND: The currently existing methods for recalculating the operation of centrifugal pumps for viscous fluids cover a sufficiently small range of viscosities. In addition, the considered papers cover the recalculation only, not the search for the optimal geometry of the centrifugal pump for high-viscosity liquids. In this paper, computational fluid dynamics tools were used to test the ability of centrifugal impellers to pump liquids with a viscosity of up to 20,000 sSt, as well as to search for the optimal geometry of the flow path.
 AIM: Determination the dependence pattern of the geometric parameters, including vanes, of the optimal geometry of the centrifugal pump flow path at various values of flow rate and viscosity.
 METHODS: A numerical modeling method based on the solving of discrete analogs of the basic equations of hydrodynamics is used in this paper.
 RESULTS: It was proved that, with the considered viscosities, an impeller with a profiled vane, but with a smaller wrap angle and height, is capable of more efficient operation than a disk impeller. The dependences of the parameters of the optimal flow paths on the characteristics for which their optimization was carried out are given.
 CONCLUSION: Based on the study results, it can be stated that it is advisable to use centrifugal impellers in case of high viscosity of the liquid, taking into account the choice of non-classical values of the geometric parameters of the flow path, including the height and angle of its vanes.

Verification of models of gas bubble break-up caused by eddies generated by a self-aspirating disk impeller

Verification of models of gas bubble break-up caused by eddies generated by a self-aspirating disk impeller

Blade Number Effects in Radial Disc Pump Impellers: Overall Performances with Cavitation Sensitivity Analysis

Straight radial impeller disc pumps are widely used in several industrial applications for hard-to-pump working flow media, such as two-phase inlet conditions, either including non-miscible bubbles or solid particles with a high concentration within the main working flow. Compared with conventional pump designs, these pumps have not been widely studied, because of their particular simple design and low efficiency values that can however reach a maximum value of 0.5 with a good pressure increase in single-phase conditions. Regarding this, no basic analysis has been performed to build one-dimensional design rules considering the relative effects of design parameters proper to these unusual designs like the blade number, blade height and disc spacing. This step is an important one for two-phase flow performance evaluations which are usually derived from single-phase ones as for conventional pumps. Two different disc pump designs with, respectively, 8 and 10 radial blades, are numerically and experimentally investigated. Experimental investigations are performed in an open loop tap water test facility, under various working conditions, combining flow rate and rotational speed variations. The overall pump performances are compared and analyzed, including cavitation onset phenomena that have been found to influence the experimental performances of both pumps. The overall performance modification between both impeller designs is analyzed. Comparisons between CFD and experimental results give reliable results and can be considered to cover a sufficiently wide range of design parameters allowing us to build future adapted design rules for such specific designs.

Benefits of Non-Destructive Evaluation and Probabilistic Damage Tolerance Cosimulation for Fracture Risk Reduction

In the context of the damage tolerance approach used to drive aircraft maintenance operations, it is essential to demonstrate the reliability of NDE inspections in detecting structural damage especially for additively manufactured components since this process produces components that may introduce material anomalies at any location within a component. The Probability Of Detection curve (POD) that links the probability to detect a detrimental flaw to its size is generally used as a key indicator for that purpose by giving the maximum flaw size that a NDE process can miss with a given level of probability and confidence. This information can then be used along with other inputs such as component geometries, mechanical properties, constraints, service and residual stresses and damage evolution speed to assess fracture risk and then adapt maintenance scenarios to optimize safety and component service life. NDE reliability and risk assessment are based on statistical indicators that need a large amount of data to provide reliable metrics. It is difficult to obtain such indicators using a purely empirical approach that is based on physical trials and measurements as it may involve many mock-ups and costly processes. Simulation tools can achieve this goal via their ability to include and precisely monitor many parameters as well as high computing capacities that are now available. The work presented in this paper involved cosimulations performed between the DARWIN® probabilistic damage tolerance software and the CIVA NDE simulation software. DARWIN computes fracture risk levels throughout a component, while CIVA can efficiently provide Probability Of Detection curves at different locations in a component and for various NDE methods. The presented application deals with a titanium gas turbine engine impeller disk and involves an Ultrasonic NDE inspection technique. It appears to be a very interesting approach to connect together NDE and Fracture mechanics simulations, two disciplines that generally work on their own. Indeed, DARWIN helps the user to determine detrimental flaw types, locations and sizes which are key inputs to develop an effective NDE inspection method. CIVA can provide location-specific POD curves that enable DARWIN to quantity the effect of dedicated NDE on potential risk reduction. This highlights the importance of NDE simulation for safety and helps to identify potential changes in the physical NDE process and the maintenance cycle that provide the best compromise between detection performance and cost.

Design and manufacturing of fertilizer spreader machine

Indian economy is based on agricultural products. In India, 58% of people are farmers. The most common crops planted by farmers are wheat, rice, corn oil crops, pulses millets, sugarcane, tea coffee, cotton and jute. India produces the majority of the world's sugarcane because of its expanding sugar demand. Our main aim is to reduce the farmer's effort in spreading fertilizer. This paper aims to reduce the human effort in spreading the chemical and dung manure fertilizer on the farm. The fertilizer is dropped through the metallic impeller disc, creating a means for applying chemical and dung manure fertilizer to fallow land. There are three layers to the product design: the top, middle, and bottom. Hopper is on the top level, an impeller disc is in the middle, and tires are on the bottom level. A frame and column support the whole design. The issue with manual fertilizer spreading equipment and the conventional method of fertilization has been resolved by this project. Due to its one-person operation, this machine fulfils the requirements of farmers who are struggling with the rising cost of fertilizer, labour costs, and unavailability of labour. This approach reduces the problems in the spreader models that are currently in use and cuts the time needed for conventional fertilizations by more than half. This approach has some drawbacks, including the inability to be employed in conditions of severe rainfall and when crops are taller than four feet.

STRESS-STRAIN STATE AND CRITICAL ROTATIONAL VELOCITIES OF AIR BLOWER ROTOR PART OF A HIGH BOOST ENGINE

The stress-strain state and critical rotation speeds of the air blower rotor part of highly forced engine are investigated. For this purpose, their parametric geometric and finite-element models are built. Due to the high speeds of rotation, the impeller disk acquires an umbrella-shaped deformed shape. This deformation can cause a gap to be selected between the impellers and the stator of the supercharger. In areas of abrupt change of shape on the impeller there is a concentration of stresses. In addition, the supercharger impeller is located cantilevered. This causes low critical speeds. These frequencies may fall within the operating range of angular velocities of the supercharger rotor. All these factors in the complex within a single calculation model were not previously taken into account. Instead, taking into account the dependences of stress, strain and critical velocity levels on the design parameters is of interest in the development of supercharger designs. In particular, the stiffness characteristics of the elastic rotor bearings were varied. The influence of these parameters on the critical rotation speeds of the rotor part of the air supercharger is determined. Recommendations have been developed for debugging from hazardous supercharger modes. In particular, it is proposed to reduce the radial stiffness of the shaft bearings by using elastic flexible rings. This can reduce critical rotor velocities beyond the operating range. In addition, a lighter material can be used to increase the strength of the impeller. It is also possible to limit the operating range of the angular rotational velocities of the rotor part of the investigated air blower. Analysis of the stress-strain state and the critical rotational velocities of the rotor were carried out on the basis of a unified generalized mathematical and numerical model. Keywords: rotor system, air blower, impeller, stress-strain state, critical rotation speed

Validation of a procedure for the numerical simulations of gas–liquid stirred tanks by means of a computational fluid dynamics approach

AbstractImpellers with concave and vertically asymmetric blades proved superior gas dispersion capabilities and power consumption characteristics under gassed turbulent conditions with respect to traditional flat‐blade turbines in aerated fermenters. In this study, a pilot‐size gas–liquid tank stirred with an asymmetric blade disk impeller is numerically investigated by means of a Reynolds averaged two‐fluid model combined with a simplified population balance model without adjustable parameters. This work aims at increasing the predictive capabilities of computational fluid dynamics multiphase modelling by validating a computational approach for the realistic simulation of industrial aerated fermenters and thus allowing for a more reliable scale‐up. A methodology for achieving fully predictive results on fundamental variables for gas–liquid stirred tanks such as gassed power consumption, overall gas hold‐up, and volumetric mass transfer coefficient, with affordable computational requirements at pilot and industrial scale is presented. Two‐phase results are compared with the experimental data collected in a geometry matching the computational domain equipped with 3 planes of 16 sensors to enable electro‐resistance tomography measurements and with suitable correlations from the literature. The limits and strength of the numerical procedure are discussed, starting from the comparison between computational predictions and experimental measurements.

An Analysis on Hydraulic Loss in a Co-Rotating Bladed Disc Pump

Disc pumps rely on the shear force generated by a co-rotating disc to transport the fluid, the interaction between the fluid and impeller is weak, providing such pumps advantages when handling multi-phase flow. In the present study, a loss analysis is presented on a different kind of disc pump that combines both shear and pressure forces using a co-rotating disc pump and radial blades and that is often applied in marine petroleum engineering for mud-lifting. Experimental measurements on the overall pump performance were performed, and the subsequent hydraulic efficiency analysis shows that similarity laws can be applied for this pump. A particular analysis was specifically performed on the impeller and shows that the resulting loss analysis indicates that the increase in the static pressure is small and that the total pressure increase is mainly contributed to by the dynamic pressure change from the inlet to the outlet impeller sections. In addition, an evaluation of the individual loss levels is proposed in the impeller that is based on one-dimensional assumptions. This type of evaluation has never been proposed for present specific TBD pump designs in the available literature. The obtained results showed that the most important loss levels are roughly equally distributed between the incidence effects, inter-blade leakage, and bolts losses in the impeller, and that all together, they can reach 80% of the total impeller losses, while the blade-loading and friction losses are relatively small. The losses downstream of the impeller are significant; thus, a specific volute design that has been adapted for a disc impeller outlet flow pattern must be considered in order to achieve better performance. The present loss analysis was able to predict the corresponding disc pump performance well, achieving a maximum error rate of ±5% for a rather wide flow coefficient range. The proposed method can be considered to be a useful approach for research or for industrial teams who are working on the same kind of geometry by adopting the same data reduction analysis, allowing them to compare their own results with the present ones.

Over-all performance analysis of a dual-entry turbocharger compressor with variable geometry orifice

A dual-entry turbocharger compressor has a dual-entry impeller with the same blades on both sides of an impeller disc. Flows merge into a common diffuser from two sides of the disc, contributing to over-all mass flow rate of the compressor, and the mass flow rate at either side is distributed with self-adaptation. With the self-adaptive distribution, the difference in the mass flow rates between two impeller sides is slight at the near choke point and gradually raises with the reduction of the compressor over-all mass flow rate. The increased mass flow rate difference can prematurely trigger compressor instability, even surge. When a turbocharged engine operates at high-altitude locations, this becomes a serious issue so that the engine fails to work. To overcome the problem, we propose a new method of using a variable geometry orifice plate at the rear entry of the dual-entry impeller. The orifice can improve the mas flow rate distribution at both impeller sides. The dual-entry compressor performance variations prove the effectiveness of the orifice in terms of the compressor stability boundary extension and suggest a control strategy of variable geometry orifice. The mechanism of the orifice extending the compressor stall margin is the pressure gradient change in front of the rear inducer. An experiment was conducted on a centrifugal compressor, and the test results support the numerical findings.

Sensitivity analysis of centrifugal compressors aerodynamic losses using 1D-mean streamline prediction technique

One-dimensional modeling and prediction of the centrifugal compressor performance are challenging as they require conservation equations and empirical and semi-empirical correlations. Therefore, there is a need to perform a consolidated study of the compressor aerodynamic loss models to conclude the importance of each loss to the compressor performance modeling. Accordingly, the purpose of this paper is to examine the effect of each aerodynamic loss on the compressor performance and explore more about which loss could have a negligible effect on the compressor performance. A MATLAB code was developed to predict the performance of five different small turbocharger centrifugal compressors at different geometric and operating conditions. The developed code was validated using the available experimental data of the investigated compressors. A sensitivity analysis methodology was performed using the validated code to check the effect of ten aerodynamic losses for the impeller and volute sections on the compressor performance. This paper concludes that impeller disk friction, blade loading, and clearance losses have a negligible effect on the small turbocharger vanless diffuser compressor performance.

Investigating the Influence of Impeller Axial Thrust Balance Holes on the Flow and Overall Performance of a Cryogenic Liquid Turbine Expander

Abstract An excessive rotor axial thrust in any turbomachine can cause critical operational problems, and rotor axial thrust balancing has always attracted much attention. The present numerical study is focused on axial thrust balancing for a cryogenic liquid turbine expander, whose axial thrust balancing is typically challenging because of its small impeller size and large axial thrust. A computational fluid dynamics (CFD) simulation is conducted in a real turbine expander environment constituted by main and gap flow domains with allowing for the thermodynamic effect of liquefied air. The balance hole influential mechanism on the main and gap flows is explored, and its influence on the expander axial thrust and overall performance is quantified. The results show that the use of balance holes creates a highly swirling gap flow, and the static pressure over the impeller disk back-side surface decreases to produce a small axial component force and axial thrust, but the turbine expander overall efficiency drops by 1.1 and 2.8 points at 100% and 50% design flow, respectively, due to an increased internal leakage loss and distorted impeller flow. In addition, a parametric study is conducted to analyze the effect of balance hole diameter, circumferential position, and radial position on expander axial thrust and overall performance. The results indicate that the axial thrust is sensitive to both the balance hole diameter and circumferential position but less sensitive to its radial position, while the overall efficiency is influenced by all three parameters.

Investigation of Flow Structure in a Narrow Clearance of a Low Specific Speed Centrifugal Impeller

Abstract The disk friction loss is remarkably large in low specific speed centrifugal pumps, and an effective reduction method has not been established. Therefore, to develop the method, the loss mechanism was investigated. To grasp the internal flow structure in the narrow clearance, both experimental and computational approaches were used. An experimental apparatus that imitates clearance between a rotating impeller disk and a stationary casing disk was used and the static pressure distribution in the radial direction was measured. The internal flow where the disk friction loss occurs was investigated. In the case of outward flow, the static pressure decreased because the influence of the centrifugal force lessened toward the outer diameter of the disk, as the flow rate surged. For this reason, the pressure gradient became steep. According to the computational fluid dynamics (CFD) analysis, there was a vortex in the cross section of the clearance. This vortex encouraged flow recirculation and promoted the increase in the circumferential velocity in the potential core. When the flow rate grew, the vortex diminished. The circumferential velocity gradient and the shear stress intensified. As a result, the disk friction escalated. In the case of inward flow, the pressure gradient became steep as the flow rate increased. There was a vortex in the clearance, the size of which lessened when the flow rate surged. The disk friction had a minimum value at the flow rate was 6 × 10−4 m3/s. This research clarified that the vortex in the clearance has a remarkable effect on reducing the disk friction.

The stress and strain analysis double-layer and eight-leaf backward curved impeller disc agitator

The mixing wing’s stress and strain value of the structure in the mixing equipment needs to be studied and discussed. The research is uses the FLUENT module to simulate the flow field state in the rotating operation of the mixing tank, the stress and strain of the mixing blade, and the modal analysis of the predicted resonance frequency. First, Fluent is uses simulate the shape of the flow field inside the stirred tank. Situation of different speeds, the deformation state of the stress, strain and total displacement of the stirring wing assembly is obtained to achieve the ANSYS fluid-solid coupling effect analysis. Finally, predict the modal appearance and failure points of the simulated stirring wing assembly at different resonance frequencies. After analysis, the rotation speed of the stirring wing is increases, it must be subjected to the centrifugal force of fluid distribution, vortex gravitation, and up and down convection agitation. The total displacement and deformation of the rigid structure of the stirring wing can be obtained. The equivalent stress and strain also adopt a progressive linear growth phenomenon.

Structural Strength and Reliability Analysis of Important Parts of Marine Diesel Engine Turbocharger

Supercharging is the main method to improve the output power of marine diesel engines. Nowadays, most marine diesel engines use turbocharging technology, which increases the air pressure and density into the cylinder and the amount of fuel injected correspondingly so as to achieve the purpose of improving the power. In a marine diesel engine, the turbocharger has become an indispensable part. The performance of turbochargers in a harsh working environment of high temperature and high pressure for a long time will directly affect the performance of diesel engine. Based on the market feedback data from manufacturers, the failure modes of compressor impeller, turbine blade, and turbine disk of marine diesel turbocharger are analyzed, and the statistical model of random factors is established. Using DOE design, the structural strength simulation data of 46 compressors and 62 turbines are obtained, and the response surface model is constructed. On this basis, Monte Carlo sampling is carried out to analyze the reliability of the compressor and turbine. The reliability of the compressor is good, while that of the turbine disk is 0.943 and that of the turbine blade is 0.96, which still has the potential of reliability optimization space. Therefore, a multiobjective optimization method based on the NSGA-II genetic algorithm is proposed to obtain the multiobjective optimization scheme data with the reliability and processing cost of turbine disk and blade as the objective function. After optimization, the reliability of turbine disk and blade is 1, the stress value of turbine blade is optimized by 4.7941%, the stress value of turbine disk is optimized by 3.0136%, the machining cost of the turbine blade is reduced by 15.5087%, and the machining cost of turbine disk is reduced by 3.9907%. At the same time, it is verified by simulation, the data based on NSGA-II multiobjective genetic algorithm are more accurate and have practical engineering reference value. The optimized data based on NSGA-II multiobjective genetic algorithm are used to manufacture new turbine samples, and the accelerated test of simulation samples is carried out. The cycle life of the optimized turbine can reach 101,697 cycles and 118,687 cycles, which is 51.75% and 77.11% longer than that of the unoptimized turbine. It can be seen that the optimized turbine can meet the requirements of the reliability index while reducing the manufacturing cost.

Calculation of disc friction power in pumps at operation on viscoelastic fluids

The flow of viscoelastic fluid in the gap between the impeller disc and the pump wall for laminar flow mode is considered. Waste water sludge (WWS) was used as a working fluid. Its flow is described by viscoplastic fluid model. The results of theoretical and experimental studies of disk friction at WWS are presented and formulas are proposed for calculation of disk friction power between wheel disks and pump body.

Design of bladeless impellers for abrasive fluid pumping

Centrifugal pumps are commonly used by mineral processing companies, such as Vale, CBMM, Kinross, and Anglo-American. As a consequence of the presence of abrasive particles in the mineral pulp, their housing and impellers readily wear out. As a result, industrial companies invest a lot of their financial resources in the maintenance of these pumps, in addition to replacing their damaged mechanical parts. To solve this problem, some researchers have been proposing novel metal alloys to improve centrifugal pump properties and mechanical endurance. In an attempt to explore a new approach, this study focuses on the disc impellers reported in Nikola Tesla’s patents. In the laboratory, an experimental bench was developed to simulate the pumping of a highly abrasive pulp composed of water and silicon carbide. An impeller base was designed to allow the assembly of 2, 3 and 4 discs. It was observed that an increase in the number of discs resulted in increased pump performance. However, the dimensions and distance between the discs depend on operational parameters, such as: dimensions of the housing and the abrasive particles to be pumped. Besides, disc impellers need to operate at higher rotations to reach the same flow and total head obtained from commercial blade impellers. In this work, the wear on the casing and on the three-disc and semi-open impellers was quantified by measuring mass losses. The disc impellers showed less wear, which provides an increase in their useful life. In addition, a three-disc impeller demonstrated high performance when compared to a semi-open impeller.

Steady-State Fluid-Solid Mixing Plane to Replace Transient Conjugate Heat Transfer Computations during Design Phase

The demand for increased turbomachinery performance, both, towards higher pressures and temperatures, leads to high thermal-loads of specific components and can critically affect mechanical integrity. In the particular case of rotating-disk configurations, like the back-side of wheels or in cavities, a very efficient way for cooling is jet impingement. An example for this situation are high pressure-ratio turbochargers, where cooling of the impeller disk (back wall) is introduced to achieve tolerable thermal loads. From the physical point of view, jet impingement on a rotating wall generates an unsteady heat transfer situation. On the other end, accurate values of time-averaged temperatures would be sufficient for design purposes. In general, obtaining circumferentially time-averaged solutions requires transient analysis of the conjugate heat transfer (CHT) process to account for the mean effect of jet cooling on solids. Such analysis is computationally expensive, due to the difference in information propagation time-scale for the solid and the fluid. In this paper, a new approach to directly compute circumferentially time-averaged (i.e., steady-state) temperature distributions for rotating-disk CHT problems is presented based on an adaption of the well known fluid-fluid mixing plane approach.

The INVESTIGATION OF THE DYNAMIC CHARACTERISTICS OF TURBINE IMPELLER DISC OF GAS TURBINE ENGINE USING ANSYS SOFTWARE

The rotating blades of a compressor or turbine in a gas turbine engine are made up of blades installed on the impeller disc. In particular, the impeller disc needs to be designed, manufactured, and installed to ensure its reliability and safety regarding the strict standards. If damage occurs during the operating process of the impeller disc, it will not only damage the motor but also endanger operators and other equipment. To increase the service time of the engine as well as shorten the production cost, gas turbine manufacturers around the globe are constantly improving technology. In which the monolithic casting impeller is an advanced technology that helps bring down the impeller mass, increasing its life by reducing the shock force on the connection the blades to the rotating disc. Nevertheless, this type of monolithic casting impeller disc reduces its damping effectiveness, which causes the oscillation force to increase significantly. In order to resolve this problem, it is necessary to look into these factors affecting the oscillation of the impeller disc. This paper presents the factors that affect the oscillation of the impeller disc through the study of the dynamic properties of its constituent components. The specific oscillation of the impeller disc, its own oscillation, as well as the impact of factors occurring during the operating of the disc was calculated by using ANSYS simulation software. By creating a three-dimensional model of the turbine blades in gas turbine engine ДP76, the individual oscillation values in a variety of engine operation modes were calculated to compare with the actual value while the engine is operating. The results have good agreement with the measured values. This affirms the advantages and prospects in applying ANSYS software to the design and manufacture of the turbine impeller disc.

Analysis of elastic supports and rotor flexibility for dynamics of a cantilever impeller

Turbochargers of modern internal combustion engines experience severe service conditions. In particular the compressor impeller is driven at extremely high angular velocity (30,000 rpm and more). Furthermore the increased requirements for the air intake dictate ever larger dimensions of the rotor disk up to 250 mm. These two factors lead to a pressing problem of stiffness, strength and dynamic stability of the newly designed units. This problem is analyzed with the help of a newly created parametric model of cantilever impeller rotor dynamics. This model accounts for the flexibility of the drive shaft and the impeller disk, quasistatic inertial and aerodynamic loads. The rotordynamics analysis is performed with a specific focus on the support behavior. The effect of initial gap and resilient characteristics of bearings and bushings is taken into account. As a result various components of displacements can be evaluated for different values of the disk diameter and angular velocity. It is critical for the design that neither radial nor axial displacement should not exceed given bounds. Furthermore, critical speeds of the studied rotor system have been determined for the various configurations of the disk and shaft dimensions. The proposed solution is to lower the first one or two eigenfrequencies of the system below the operating domain, so that the rotor becomes stable to any external excitations. Altogether, the developed mechanical analysis tool has proved itself as a useful tool for the engineering practice that allows to eliminate fatal flaws at early design stages.

Turbulent Energy Dissipation Rate and Turbulence Scales in the Blade Region of a Self-Aspirating Disk Impeller

Turbulent Energy Dissipation Rate and Turbulence Scales in the Blade Region of a Self-Aspirating Disk Impeller