Manufacturing and mechanical characterization of Al<Subscript>2</Subscript>O<Subscript>3</Subscript>/β-TCP/TiO<Subscript>2</Subscript> biocomposite as a potential bone substitute

This paper focuses on the mechanical characterization of a bioceramic based on commercial alumina (Al₂O₃) mixed with synthesized tricalcium phosphate (β-TCP) and commercial titania powder (TiO₂). The effect of β-TCP and TiO₂ addition on the mechanical performance was investigated. After a sintering process at 1600 °C for 1 h, various mechanical properties of the samples have been studied, such as compressive strength, flexural strength, tensile strength, elastic modulus, and fracture toughness. The measurements of the elastic modulus (E) and the tensile strength (σ _t ) were conducted using the modified Brazilian test while the compressive strength (σ _c ) was determined through a compression test. Also, semi-circular bending (SCB) specimens were used to evaluate the flexural strength (σ _f ) and the opening mode fracture toughness (K _IC). From the main results, it was found that the best mechanical performance is obtained with the addition of 10 wt.% TCP and 5 wt.% TiO₂. Alumina/10 wt.% tricalcium phosphate/5 wt.% titania composites displayed the highest values of mechanical properties and a good combination of compressive strength (σ _c ?≈?352 MPa), flexural strength (σ _f ?≈?98 MPa), tensile strength (σ _t ?≈?86.65 MPa), and fracture toughness (K _IC?≈?13 MPa m^1/2).     

Experimental investigations on effects of tool flank wear on surface integrity during orthogonal dry cutting of Ti-6Al-4V

Machining titanium alloy Ti-6Al-4V is a challenging task since tool flank wear adversely affects surface integrity. Quantitative effects of predetermined tool flank wear values (VB) on the surface integrity were investigated through the orthogonal dry cutting of Ti-6Al-4V. Experimental results indicated that three-dimensional (3D) average surface roughness increased with the VB ranging from 0 to 0.2 mm but decreased at VB = 0.3 mm. Given the effects of rubbing and ironing enhanced, surface material burning and plastic flows emerged on the machined surface at VB = 0.3 mm. Not only the plastic deformation layer became deeper but also the grains were greatly distorted with the increase of tool flank wear. When machined by using the tool at VB = 0.3 mm, the β phase of Ti-6Al-4V decreased near the machined surface layer than that of using the fresh tool. Besides, the depth of work-harden layer increased from 20 to 60 μm with the VB increasing from 0 to 0.3 mm. The softened layer was generated near the machined surface by using the tool at VB = 0.3 mm. In addition, the residual compressive stresses of the machined surface had the trend of decreasing. Experimental results indicated that the VB less than 0.2 mm was the most suitable condition for better surface integrity during orthogonal dry cutting of Ti-6Al-4V. This study aims at providing experimental data for optimizing the processing parameters and improving the surface integrity of Ti-6Al-4V.     

Effect of Oxygen on the Self-formation of Carbonaceous Tribo-layer with Carbon Nitride Coatings under a Nitrogen Atmosphere

The ball-on-disk friction and wear tests of CN _X coatings (CN _X /CN _X ) were conducted under a nitrogen atmosphere with controlled relative humidity (RH) (3.4–40.0%RH) and oxygen concentration (100–21 × 10⁴ ppm) in this study. We found that the specific wear rate of CN _X coating on ball (W _b), which could give stable and low friction coefficient (<0.05), was below 3.0 × 10^?8 mm³/Nm. Average friction coefficients (µ _a) and W _b of CN _X /CN _X increased (µ _a: 0.02–0.33, W _b: 1.6 × 10^?8–2.4 × 10^?7 mm³/Nm) with increasing oxygen concentration (230–211,000 ppm) as well as RH (4.7–21.1%RH) under a nitrogen atmosphere. However, the W _b remained low value below 2.3 × 10^?8 mm³/Nm regardless of oxygen concentration (100–207,000 ppm) of a nitrogen atmosphere (3.4–3.9%RH) when CN _X -coated balls were slid against a hydrogenated CN _X (CN _X :H) coatings (CN _X /CN _X :H). Besides, the CN _X /CN _X :H achieved low and stable friction coefficient below 0.05 under a nitrogen atmosphere (10,000 ppmO₂) regardless of increasing RH up to 20%RH. Raman analysis indicated that the structure of carbon on the top surface of CN _X coating was changed from as-deposited CN _X coating in the case of low friction coefficient (<0.05). Furthermore, TOF-SIMS analysis provided the evidence that the carbon derived from CN _X -coated disk was considered to diffuse into the ball surface, and it mixed with the carbon derived from CN _X -coated ball on the wear scar, which formed the chemically bonded carbon tribo-layer. Low friction coefficient (<0.05) with CN _X coatings under a nitrogen atmosphere was achieved due to self-formation of the carbon tribo-layer.     

Calculation of negative-pressure chip in suction-type internal chip removal system and analysis of influencing factors

Compacted graphite iron (CGI) is considered as the ideal material to make modern fuel-efficient diesel engine. Due to the vermicular or worm-like graphite distributed among the ferrite/pearlite matrix, CGI behaves better physical and mechanical properties in comparison with gray cast iron (GCI) and spherical graphite spheroidal cast iron (SGI). However, these good properties bring about the machining challenges. So it is important to appropriately select cutting parameters to machine this material with economy and efficiency. The present study investigated the influence of cutting parameters, such as cutting speed V, feed rate f, and exit angle Ψ, on workpiece material removal volume Q and cutting burr height on the entrance side H₁ and on the exit side H₂ during high-speed milling of CGI by the coated carbide tools_. On this basis, the relatively optimum high-speed cutting parameters were selected under the research condition. Cutting tool failure mechanism was also investigated with the aid of scanning electronic microscope (SEM) and energy-dispersive system (EDS) (SUPRA55, Germany) analysis. The results showed that Q, H₁, H₂, and the type of cutting burr on the exit side of the machined surface could be influenced by the cutting parameters. And the relatively optimum cutting parameters are V = 800 m/min, f = 0.25 mm/rev, and Ψ = 60°. Adhesive wear and thermal cracks which were perpendicular to the cutting edge were common wear mechanisms during the cutting process. However, with an increase in feed rate, mechanical cracks which were parallel to the cutting edge could be found on the flank face of the cutting tool.     

Big data analysis of a mini three-axis CNC machine tool based on the tuning operation of controller parameters

The characteristic responses of a mini three-axis computer numerical control (CNC) machine tool based on the controller tuning operation were investigated for big data estimation. The major tuning parameters included the position control gains K _p, the position feed-forward control gains K _f, the speed control gains K _v, and the gain ratios K _g of the position and speed control values in manufacturing industries. K _p gains of 10, 30, 50, 80, 100, 200, 300, and 400 rad/s, K _f gains of 0, 30, 50, 60, 80, and 100 %, K _v gains of 30, 50, 70, 100, 300, 900, 2000, and 3000 rad/s, and K _g ratios of (1:1), (3:1), (5:1), and (7:1) were analyzed for smart productivity. The results show that the settling times at different K _p values were almost constant when the K _p gain was over 200 rad/s. The maximum overshoots, when the feed-forward gain is over 60 %, almost increased with increasing feed-forward gains. However, the overshoot of the three-axis CNC machine tool decreased as the K _v gain increased until the K _v gain reached 70 rad/s. The settling times at a constant K _g ratio decreased with an increase in the K _p and K _v gains. The characteristic responses of the tuning operations were enabled with connectivity to a cloud network to share the big data, to support decision making, and to adjust operations in real time.     

Lubricity of High Water Content Aqueous Gels

Aqueous gels such as biopolymer gels, mucus, and high water content hydrogels are often qualitatively described as lubricious. In hydrogels, mesh size, ξ, has been found to be a controlling parameter in friction coefficient. In the tribology of aqueous gels, we suggest that the Weissenberg number (Wi) is a useful parameter to define different regimes, and following the original formulations in rheology, Wi is given by the polymer relaxation time (ηξ³/k_BT) multiplied by the shear rate due to fluid shear through a single mesh (V/ξ): Wi?=?ηVξ²/k_BT. At sliding speeds below a Weissenberg number of approximately 0.1, Wi?<?0.1, the friction coefficient is velocity-independent and scales with mesh size to the ??1 power, µ ∝ ξ^?1. De Gennes’ scaling concepts for elastic modulus, E, give a dependence on polymer mesh size to the ??3 power, E ∝ ξ^?3, and following Hertzian contact analysis, the contact area is found to depend on the mesh size squared, A ∝ ξ². Combining these concepts, the shear stress, τ, and therefore the lubricity of aqueous gels, is predicted to be highly dependent on the mesh size, τ ∝ ξ^?3. Studies aimed at elucidating the fundamental mechanism of lubricity in biopolymer gels, mucus, and hydrogels have wrestled with comparisons across mesh size, which can be extremely difficult to accurately quantify. Using scaling concepts relating polymer mesh size to water content reveals that shear stress decreases rapidly with increasing water content, and plots of shear stress as a function of swollen water content are suggested as a useful method to compare aqueous gels of unknown mesh size. As a lower bound, these data are compared against estimates of fluid shear stress for free and bound water flowing through a mesh size estimated by the water content of the gels. The results indicate that the strong dependence on lubricity is likely due to a synergistic combination of a low viscosity solvent (water) coupled to a system that has a decreasing friction coefficient, modulus, and the resulting contact pressure with increasing water content. Although the permeability, K, of aqueous gels increases dramatically with water content (and mesh size), K ? ξ²/η, the stronger decrease of the elastic modulus and subsequent decrease in contact pressure due to an increase in the contact length, predicts that the draining time under contact, t, actually increases strongly with increasing water content and mesh size, t ∝ ξ². Consistent with the finding of extremely high water content aqueous gels on the surfaces of biological tissues, these high water content gels are predicted to be optimal for lubrication as they are both highly lubricious and robust at resisting draining and sustaining hydration.     

Adatom concentration distribution on an extrawide Si(111) terrace during sublimation

The formation of an adsorption layer on the Si(111) surface during sublimation at temperatures of 1000–1100 °C and subsequent quenching at T = 750 °C is studied by methods of in situ ultrahigh-vacuum reflection electron microscopy and ex situ atomic force microscopy. The adatom concentration distribution on an extrawide (~60 μm) atomically flat terrace is determined for the first time, and the diffusion length x_s = 31±2 μm at T = 1000 °C is obtained. The analysis of the temperature dependence of the equilibrium concentration of adatoms near a monatomic step allows pioneering measurements of the energy necessary for adatom detachment from the step and attachment to the terrace E _ad ≈ 0.68 eV. Based on these results, the energy parameters for some atomic processes on the Si(111) surface are estimated.     

Parametric optimization of CNC turning process for hybrid metal matrix composite

Machining of hybrid metal matrix composite is difficult as the particulates are abrasive in nature and they behave like a cutting edge during machining resulting in quick tool wear and induces vibration. An attempt was made in this experimental study to evaluate the machining characteristics of hybrid metal matrix composite, and a mathematical model was developed to predict the responses, namely surface finish, intensity of vibration and work-tool interface temperature for known cutting condition while machining was performed in computer numerical control lathe. Design of experiments approach was used to conduct the trials; response surface methodology was employed to formulate a mathematical model. The experimental study inferred that the vibration in V _x, V _y, and V _z were 41.59, 45.17, and 26.45 m/s², respectively, and surface finish R _a, R _q, and R _z were 1.76, 3.01, and 11.94 μm, respectively, with work-tool interface temperature ‘T’ of 51.74 °C for optimal machining parameters, say, cutting speed at 175 m/min, depth of cut at 0.25 mm and feed rate at 0.1 mm/rev during machining. Experimental results were in close conformity with response surface method overlay plot for responses.     

Numerical and experimental study on the flow characteristics of abrasive slurry jet with polymer additives

Based on a refined mathematical model, the hydrodynamics of abrasive slurry jet (ASJ) was numerically investigated in consideration of the non-Newtonian rheological properties of the slurry. It is found that adding polymer has significant effects on the jet properties, such as axial velocity and abrasive volume fraction. The coherence length (L _c) is proposed to measure the initial region of jet, where external air acts insignificantly on the axial velocity magnitude and thus the averaged kinetic energy is large. In the ASJ flow field, L _c is increased after adding polymer additives, while reduced as the operating pressure (P ₀) goes up. The prediction to the L _c agrees well with the experimental results, with P ₀ ranging from 1 to 16 MPa. Accordingly, an empirical formula is presented to describe the relationship between L _c and P ₀. The distinct characteristics of ASJ with polymer additives together with the verified length model of coherence region provides a qualitative and quantitative basis for the optimization of ASJ machining process, for instance, improving cutting efficiency and precision.     

Experimental investigation of the preferred Strouhal number used in self-resonating pulsed waterjet

Self-resonating pulsed waterjet (SRPW) is superior to plain waterjet in many ways and is being employed in numerous applications. To further improve the performance of SRPW, the optimal value of the preferred Strouhal number (S_d), which is used to determine the chamber length of a self-resonating nozzle, was experimentally studied at inlet pressures of 10 MPa and 20 MPa. The axial pressure oscillation peak and amplitude were used to evaluate the performance of SRPW, in order to find the optimum S_d value. Results show that S_d value determines the self-resonance behavior of an organ-pipe nozzle and greatly affects the intensity of the axial pressure oscillation. Under the experimental conditions, the optimum S_d values are 0.315 and 0.278 respectively, corresponding to inlet pressures of 10 MPa and 20 MPa. Compared with the default value of 0.3 obtained from air jet experiment, the optimum S_d value at inlet pressure of 10 MPa is a little larger and oppositely a bit smaller at inlet pressure of 20 MPa. Thus, if the inlet pressure is not considered, S_d value of 0.3 is reasonable for determining the chamber length of a self-resonating nozzle for generating effective SRPW.     

Optimization of flux-cored arc welding process parameters by using genetic algorithm

The effect of flux-cored arc welding (FCAW) process parameters on the quality of the super duplex stainless steel (SDSS) claddings can be studied using Taguchi L9 design of experiments. In this experimental investigation, deposits were made with 30 % bead overlap. Establishing the optimum combination of process parameters is required to ensure better bead geometry and desired properties. The above objectives can be achieved by identifying the significant input process parameters as input to the mathematical models like welding voltage (X ₁), wire feed rate (X ₂), welding speed (X ₃), and nozzle-to-plate distance (X ₄). The identified responses governing the bead geometry are bead width (W) and height of the reinforcement (H). The mathematical models were constructed using the data collected from the experiments based on Taguchi L9 orthogonal array. Then, the responses were optimized using non-traditional nature-inspired technique like genetic algorithm (GA).     

Investigate on milling force of cryogenic cooling processing aluminum honeycomb treated by ice fixation

Aerospace metal honeycomb materials with low stiffness had often the deformation, burr, collapse, and other defects in the mechanical processing. They were attributed to poor fixation method and inapposite cutting force. This paper presented the improvement of fixation way. The hexagonal aluminum honeycomb core material was treated by ice fixation, and the NC milling machine was used for a series of cryogenic machining. Considering the similar structure of fiber-reinforced composite materials, the milling force prediction model of ice fixation aluminum honeycomb was established, considering tool geometry parameters and cutting parameters. Meanwhile, the influence rule on milling force was deduced. The results show that compared with the conventional fixation milling method, the honeycomb processing effect is improved greatly. The machining parameters affect order on milling forces: the cutting depth is the most important, followed by the cutting width, then the spindle speed and the feed. Moreover, too small cutting depth (a_p?=?0.5 mm) will cause insufficient cutting force, while a_p?>?2 mm with higher force will reduce the processing quality of honeycomb. Simultaneously, the honeycomb orientation (θ) has a great influence on processing quality. Using the model, the predicted and measured error values of the feed and main cutting force are all small in θ?<?90°. But, the rate is 33 and 26% for the main cutting force and feed force error in θ?>?90°, respectively, while they all exhibit the smallest error in θ?=?60°. This bigger error mainly is due to unstable cutting force with obtuse angle. In addition, the tool rake angle has little influence on cutting quality in θ?<?90°, but bigger on that in θ?>?90°. Furthermore, the calculation model successfully conforms to the main deformation mechanism and influences parameters of the cutting force in the milling process, and it can accurately predict the cutting force in θ?<?90° and guide the milling process.     

Soft computing models and intelligent optimization system in electro-discharge machining of SiC/Al composites

In this paper, a multi-variable regression model, a back propagation neural network (BPNN) and a radial basis neural network (RBNN) have been utilized to correlate the cutting parameters and the performance while electro-discharge machining (EDM) of SiC/Al composites. The four cutting parameters are peak current (I_p), pulse-on time (T_on), pulse-off time (T_off), and servo voltage (S_v); the performance measures are material remove rate (MRR) and surface roughness (Ra). By testing a large number of BPNN architectures, 4-5-1 and 4-7-1 have been found to be the optimal one for MRR and Ra, respectively; and it can predict them with 10.61 % overall mean prediction error. As for RBNN architectures, it can predict them with 12.77 % overall mean prediction error. The multivariable regression model yields an overall mean prediction error of 13.93 %. All of these three models have been used to study the effect of input parameters on the material remove rate and surface roughness, and finally to optimize them with genetic algorithm (GA) and desirability function. Then, an intelligent optimization system with graphical user interface (GUI) has been built based on these multi-optimization techniques, in which users can obtain the optimized cutting parameters under the desired surface roughness (Ra).     

Integrated ANN-LWPA for cutting parameter optimization in WEDM

In this paper, we present a new approach to determinate cutting parameters in wire electrical discharge machining (WEDM), integrated artificial neuron network (ANN), and wolf pack algorithm based on the strategy of the leader (LWPA). The cutting parameters considered in this paper are pulse-on, current, water pressure, and cutting feed rate. Models of the effects of the four parameters on machining time (T_p), machining cost (C_p), and surface roughness (Ra) are mathematically constructed. An ANN-LWPA integration system with multiple fitness functions is proposed to solve the modelling problem. By using the proposed approach, this study demonstrates that T_p, C_p, and Ra can be estimated at 164.1852 min, 239.5442 RMB, and 1.0223 μm in single objective optimization, respectively. For example, as for Ra, integrated ANN-LWPA has optimized the Ra value by the reduction of 0.1337 μm (11.6 %), 0.3377 μm (24.8 %), and 0.105 μm (10.3 %) compared to experimental data, regression model, and ANN model, respectively. Consequently, the ANN-LWPA integration system boasts some advantages over decreasing the value of fitness functions by comparison with the experimental regression model, ANN model, and conventional LWPA result. Moreover, the proposed integration system can be also utilized to obtain multiple solutions by uniform design-based exploration. Therefore, in order to solve complex machining optimization problems, an intelligent process scheme could be integrated into the numeric control system of WEDM.     

Impact of aspect ratio and surface heating on pollutant transport in street canyons

This paper investigated the impacts of surface heating on pollutant transport and Air Exchange Rate (AER) in street canyons of different aspect ratios (building heightH to street widthW) using computational fluid dynamic (CFD) technique. Street canyons ofH/W varied from 0.1 to 2 were employed in the study. These street-canyon aspect ratios covered a range of basic flow regimes including skimming flow (H/W=1 and 2), wake interference flow (H/W=0.5), and isolated roughness flow (H/W=0.1). Different façade/surface heating imposed different influence on the flow field and pollutant transport in street canyons of differentH/W. The AER induced by vertical velocity fluctuationAER _w, and mean vertical velocityAER _w . AER of street canyon with differentH/W and different surface heating exhibited their unique characteristics.     

Vibration response analysis caused by rubbing between rotating blade and casing

Two types of blade-tip rubbing due to the static misalignment of the bladed-disk center and casing center and casing deformation are simulated. By applying aerodynamic load in the blade lateral/flexural direction, vibration responses due to blade-casing rubbing are analyzed under the run-up process with constant angular acceleration and the steady-state process at 10000 rev/min. The effects of some parameters, such as the static misalignment e _c, casing stiffness k _c and casing deformation n _p, on the system vibration responses are also illustrated by spectrum cascades, time-domain waveforms of displacement, normal rubbing forces, amplitude spectra and the impulse P in a single blade-casing rubbing period. The results show that blade-tip rubbing will cause amplitude amplification and harmonic resonance phenomena when the multiple frequencies (nf _r) of rotational frequency (f _r) coincide with the first three flexural dynamic frequencies of the blade (f _n1, f _n2 and f _n3). For example, the displacement amplitudes at 3f _r, 14f _r and 38f _r are large and the vibration is dominant near f _n1. In addition, the casing deformation mainly excites the dominant Blade passing frequency (BPF), which is related to the casing deformation coefficient n _p. By comparing these impulse values, for the selected parameters in this paper, the casing stiffness has a greater effect on impulse than the static misalignment and casing deformation coefficient. The impulse shows a linear increase trend with the increasing static misalignment, and it decreases under the large n _p because the contact time decreases with the increase of n _p.     

Experimental and numerical research on magnetic pulse forming of DP600 high-strength steel with driver sheet

This study aims to investigate the effect of the three cutting parameters (rotation, feed rate, and number of tool strokes) on the values of roughness (Rk, Rpk, Rvk, Mr1, Mr2, Rp/Rt ratio, and Vo) in flexible honed crankcase cylinder of hermetic compressors. The study was based on a full factorial design 2 × 2 × 3, where the rotation and the feed rate were investigated in two levels and the number of tool strokes in three levels. The cylinders were initially honed using a multi-spindle honing machine, Gehring model. A set of three honing tools was used each with two strokes, the first for roughing (120 mesh), the second for semi-finishing (270 mesh), and the third for finishing (600 mesh). For conventional honing (CH), the depth of the cut and the feed rate were kept constant. The flexible honing process was carried out after conventional honing (C+FH) in a CNC milling machine using a Silicon Carbide flex hone tool 800 mesh and 24.2 mm nominal diameter considering 12 different cutting conditions. An electromechanical surface roughness tester was used to carry out roughness measurements. The measurement uncertainty was assessed following the recommendations of the GUM-JCGM 101. The analysis of variance (ANOVA) technique was applied, and it was observed that the number of the tool strokes was the factor that contributed the most to the improvement of the surface finish of the cylinders.     

Determination of a coupling equation for milling parameters based on optimal cutting temperature

Nanofluid minimum quantity lubrication (NMQL) is one of the main modes of sustainable manufacturing. It is an environment-friendly, energy-saving, and highly efficient lubrication method. With the use of nanoparticles, the tribological properties of debris–tool and workpiece–tool interfaces will change. However, spectrum analyses of force and power spectral density (PSD) of surface microstructures are limited. In the present work, the milling force, friction coefficient, specific energy, surface roughness, and surface microstructure of debris were evaluated in milling of 45 steel for different lubrication conditions, namely, dry, flood, minimum quantity lubrication, and Al₂O₃ NMQL. Results demonstrated that compared with other lubrication conditions, NMQL achieves minimum milling force peak (F_x?=?270 N, F_y?=?160 N, F_z?=?50 N), friction coefficient (μ?= 1.039), specific energy (U?= 65.5 J/mm³), and surface roughness value (R_a?=?2.254 μm, RS_m?=?0.0562 mm). Furthermore, a spectrum analysis of the milling force and PSD of the surface microstructure was conducted for validation. The spectral analysis of milling force revealed that NMQL obtained the lowest milling force and amplitude in the middle-frequency region, thereby indicating the minimum abrasion loss of the tool. Meanwhile, the PSD analysis indicated that NMQL had the lowest proportional coefficient in the low-frequency region (0.4766) and the highest proportional coefficient in the high-frequency region (0.0569). These results revealed that the workpiece surface gained by Al₂O₃ NMQL obtained higher wave fineness than other working conditions. By combining with the lowest R_a, NMQL contributes the best workpiece surface quality. Therefore, machining experiments using NMQL showed the best lubrication performance.     

Numerical and experimental investigation on the diffuser optimization of a reactor coolant pump with orthogonal test approach

The diffuser of a reactor coolant pump was optimized using an orthogonal approach with numerical simulation to improve the pump hydraulic performance. Steady simulation was conducted by solving Reynolds-averaged Naiver-Stokes equations with the SST k-ω turbulence model using CFX code. The influence of the diffuser geometric parameters, namely, S, φ, α ₄, b ₄, δ ₂, R _t and R ₄, on the pump performance were determined. L₁₈ (3⁷) orthogonal table was chosen for the optimization process. Best indicators were determined, and range analysis of energy losses, head, and efficiency at the rated condition was performed. Optimal parameters of the diffuser were S = 490 mm, φ = 36°, α ₄ = 30°, b ₄ = 200 mm, δ ₂ = 20 mm, R _t = 5 mm and R ₄ = 565 mm. The final design was experimentally tested. Simulation results showed more remarkable performance than the experimental result. However, the numerical predictions and experimental results were consistent, validating the design procedure. Loading of the impeller and diffuser blades was analyzed to investigate the direct impact on the hydrodynamic flow field. The head was 14.74 m, efficiency was 79.6 %, and efficiency of the prototype pump was 83.3 % when the model pump functioned at the rated conditions. Optimization results showed that efficiency and head were improved at the design condition.