Efficiency characteristics of piezostack pump for linear actuators

A piezostack pump for linear actuators is presented and studied in terms of mechanical energy efficiency (MEE), energy conversion efficiency (ECE) and design method. MEE is defined as the ratio of the output mechanical energy to that converted from input electrical energy, and ECE is the ratio of output mechanical energy to input electrical energy. The analysis results show that both MEE and ECE decrease with the increase of stiffness of the chamber diaphragm (k_s), which is a function of the radius ratio (rigid disk radius to chamber radius). There is respective optimal external load (F_c) for them to achieve peak value for a given piezostack with blocked force (F_b) and stiffness (k_a). The optimal force ratio (F_c/F_b) is a constant of 0.5 for maximum MEE, and between 0.57 and 0.5 for maximum ECE. Considering the deflection of the pump chamber and dynamic response of the piezostack, the stiffness ratio (k_s/k_a) should be limited between 0.3 and 1, and the relative radius ratio is between 0.7 and 0.8. With the increase of the radius ratio in the range, the maximal MEE decreases from 0.38 to 0.25, and the peak ECE decreases from 0.20 to 0.14.     

Ants colony algorithm approach for multi-objective optimisation of surface grinding operations

An ant colony based optimisation procedure has been developed to optimise grinding conditions, viz. wheel speed, workpiece speed, depth of dressing and lead of dressing, using a multi-objective function model with a weighted approach for the surface grinding process. The procedure evaluates the production cost and production rate for the optimum grinding condition, subjected to constraints such as thermal damage, wheel wear parameters, machine tool stiffness and surface finish. The results are compared with Genetic Algorithm (GA) and Quadratic Programming (QP) techniques.Nomenclature a _p down feed of grinding (mm/pass) - a _w total thickness of cut (mm) - A _o initial wear flat-area percentage (%) - b _e empty width of grinding (mm) - b _s width of wheel (mm) - b _w width of workpiece (mm) - B _k positive definite approximation of the Hessian - doc depth of dressing (mm) - c _d cost of dressing ($) - c _s cost of wheel per mm³ ($/mm³) - CT total production cost ($/pc) - CT ^* expected production cost limit ($/pc) - d _g grind size (mm) - D _e diameter of wheel (mm) - f _b cross feed rate (mm/pass) - G grinding ratio - k _a constant dependent on coolant and wheel grind type - k _u wear constant (mm^-1) - k _c cutting stiffness (N/mm) - k _m static machine stiffness (N/mm) - k _s wheel wear stiffness (N/mm) - L lead of dressing (mm/rev) - L _e empty length of grinding (mm) - L _w length of workpiece (mm) - M _c cost per hour labour and administration ($/h) - N _d total number of pieces to be grouped during the life of dressing (pc) - N _t batch size of workpieces (pc) - N _td total number of workpieces to be grouped during the life of dressing (pc) - P number of workpieces loaded on the table (pc) - R _a surface roughness (µm) - R _a* surface finish limit during rough grinding (µm) - R _c workpiece hardness (Rockwell hardness number) - R _em dynamic machine characteristics - S _d distance of wheel idling (mm) - S _p number of spark out grinding (pass) - t _sh time of adjusting machine tool (min) - t _i time of loading and unloading workpiece (min) - T _ave average chip thickness during grinding (µm) - U specific grinding energy (J/mm) - U ^* critical specific grinding energy (J/mm³) - V _r speed of wheel idling (mm/min) - V _s wheel speed (m/min) - V _w workpiece speed (m/min) - VOL wheel bond percentage (%) - WRP workpiece removal parameter (mm³/min-N) - WRP ^* workpiece removal parameter limit (mm³/min-N) - WWP wheel wear parameter (mm³/min-N) - W _i weighting factor, 0W _i1 (W ₁+W ₂+W ₃=1)     

A universal slip-line model with non-unique solutions for machining with curled chip formation and a restricted contact tool

A universal slip-line model and the corresponding hodograph for two-dimensional machining which can account for chip curl and chip back-flow when machining with a restricted contact tool are presented in this paper. Six major slip-line models previously developed for machining are briefly reviewed. It is shown that all the six models are special cases of the universal slip-line model presented in this paper. Dewhurst and Collins's matrix technique for numerically solving slip-line problems is employed in the mathematical modeling of the universal slip-line field. A key equation is given to determine the shape of the initial slip-line. A non-unique solution for machining processes when using restricted contact tools is obtained. The influence of four major input parameters, i.e. (a) hydrostatic pressure (P_A) at a point on the intersection line of the shear plane and the work surface to be machined; (b) ratio of the frictional shear stress on the tool rake face to the material shear yield stress (τ/k); (c) ratio of the undeformed chip thickness to the length of the tool land (t₁/h); and (d) tool primary rake angle (γ₁), upon five major output parameters, i.e. (a) four slip-line field angles (θ, η₁, η₂, ψ); (b) non-dimensionalized cutting forces (F_c/kt₁w and F_t/kt₁w); (c) chip thickness (t₂); (d) chip up-curl radius (R_u); and (e) chip back-flow angle (η_b), is theoretically established. The issue of the “built-up-edge” produced under certain conditions in machining processes is also studied. It is hoped that the research work of this paper will help in the understanding of the nature and the basic characteristics of machining processes.     

Computer-aided selection of optimum machining parameters in multipass turning

In this paper a model and the interactive program system MECCANO2 for multiple criteria selection of optimal machining conditions in multipass turning is presented. Optimisation is done for the most important machining conditions: cutting speed, feed and depth of cut, with respect to combinations of the criteria, minimum unit production cost, minimum unit production time and minimum number of passes. The user can specify values of model parameters, criterion weights and desired tool life. MECCANO2 provides graphical presentation of results which makes it very suitable for application in an educational environment.Nomenclature a _min,a _max minimum and maximum depth of cut for chipbreaking [mm] - a _w maximum stock to be machined [mm] - C _a, _a, _a coefficient and exponents in the axial cutting force equation - C _r, _r, _r coefficient and exponents in the radial cutting force equation - C _T, , , coefficient and exponents in the tool life equation - C _v, _v, _v coefficient and exponents in the tangential cutting force equation - D _w maximum permissible radial deflection of workpiece [mm] - F _a axial cutting force [N] - F _b design load on bearings [N] - F _c clamping force [N] - F _k ^/* minimum value of criterionk, k=1, ...,n, when considered separately - f _m rotational flexibility of the workpiece at the point where the cutting force is applied [mm Nm^–1] - f _r radial flexibility of the workpiece at the point where the cutting force is applied [mm N^–1] - F _r radial cutting force [N] - F _tmax maximum allowed tangential force to prevent tool breakage [N] - F _v tangential cutting force [N] - k slope angle of the line defining the minimum feed as a function of depth of cut [mm] - l length of workpiece in the chuck [mm] - L length of workpiece from the chuck [mm] - L _c insert cutting edge length [mm] - M _g cost of jigs, fixtures, etc. [$] - M _o cost of labour and overheads [$/min] - M _u tool cost per cutting edge [$] - n number of criteria considered simultaneously - N _q, N_p minimum and maximum spindle speed [rev/min] - N _s batch size - N _z spindle speed for maximum power [rev/min] - P _a maximum power at the point where the power-speed characteristic curve changes (constant power range) [kW] - R tool nose radius [mm] - r workpiece radius at the cutting point [mm] - r _c workpiece radius in the chuck [mm] - s _min,s _max minimum and maximum feed for chipbreaking [mm] - T tool life [min] - T _a process adjusting time [min] - T _b loading and unloading time [min] - T _d tool change time [min] - T _des desired tool life [min] - T _h total set-up time [min] - T _t machining time [min] - V _rt speed of rapid traverse [m/min] - W volume of material to be removed [mm³] - W _k weight of criterionk, k=1, ...,n - x=[x ₁,x ₂,x ₃ ] ^T vector of decision variables - x ₁ cutting speed [m/min] - x ₂ feed [mm/rev] - x ₃ depth of cut [mm] - approach angle [rad] - _a coefficient of friction in axial direction between workpiece and chuck - _c coefficient of friction in circumferential direction between workpiece and chuck     

In-process estimation of radial immersion ratio in face milling using cutting force

In order to prevent tool breakage in milling, maximum total cutting force is regulated at a specific constant level, or threshold, through feed rate control. Since the threshold is a function of the immersion ratio, an estimation of the immersion ratio is necessary to flexibly determine the threshold. In this paper, a method of in-process estimation of the radial immersion ratio in face milling is presented. When an insert finishes sweeping, a sudden drop in cutting forces occurs. These force drops are equal to the cutting forces that act upon a single insert at the swept cutting angle and they can be acquired from cutting force signals in the feed and cross-feed directions. Average cutting forces per tooth period can also be calculated from the cutting force signals in two directions. The ratio of cutting forces acting upon a single insert at the swept angle of cut and the ratio of average cutting forces per tooth period are functions of the swept angle of cut and the ratio of radial to tangential cutting force. Using these parameters, the radial immersion ratio is estimated. Various experiments are performed to verify the proposed method. The results show that the radial immersion ratio can be estimated by this method regardless of other cutting conditions.Nomenclature F_T, F_R tangential and radial forces - F_X, F_Y cutting forces in feed direction and cross feed direction - dF_X, dF_Y cutting force differences before and after the immersion angle in X and Y direction - K_s specific cutting pressure - a depth of cut - r ratio between tangential force and radial force - s_t feed per tooth - instantaneous angle of cut - _s swept angle of cut - _T tooth spacing angle - w radial width of cut - R cutter radius - z number of inserts     

Influence of Punch Radius and Angle on the Outward Curling Process of Tubes

Using the theory of updated Lagrangian formulation, this study adopted the elasto-plastic finite-element method and extended the increment determination method, the r_min method, to include the element’s yielding, nodal contact with or separation from the tool, maximum strain and limit of rotation increment. The computer code for a finite-element method is established using the modified Coulomb’s friction law. Conical punches with different radii and angles are used in the forming simulation of hard copper and brass tube ends. The effects of various elements including the half-apex angle of punch (α) and its radius (R), the ratio of the thickness of the tube wall to the mean diameter of tube, mechanical properties, and lubrication on the tube’s outward curling, are investigated. Simulation findings indicate that when the bending radius at the punch inlet (ρ) satisfies the condition of ρ≤ρ _c , curling is present at the tube end. On the other hand, if ρ≥ρ _c , the tube end experiences flaring. The variable ρ _c is called the critical bending radius. The value of ρ _c increases as the value of α increases. Furthermore, the findings also show that ρ _c is neither correlated with tube material nor lubrication.     

Optimal configuration selection method for stiffness identification of serial manipulators based on the κf(A)−1 criterion

In real industrial environment, the stiffness identification accuracy of manipulators is affected by various measurement errors. However, research that deals with the inevitable error perturbation is scarce. The κ_F(A)⁻¹ criterion is adopted for measurement configuration selection to solve this problem according to the perturbation analysis and derivation of solutions to systems of stiffness identification equations. The optimal measurement configurations are finally obtained using the DETMAX optimization algorithm based on the deduced criterion, which is the main contribution of this work. Results illustrate that the optimal configurations optimized by the DETMAX algorithm based on the κ_F(A)⁻¹ criterion can better overcome the influence of measurement errors, improve the identification accuracy, and reduce the compensated position error and fluctuation compared with the other optimization algorithms. Furthermore, the proposed criterion can be applied to the stiffness identification of serial manipulators in a real industrial environment.

     

Improved wear resistance of Si3N4 tool inserts by addition of Al2O3 platelets

In the present work, Si₃N₄ matrix composites reinforced with different amounts of Al₂O₃ platelets (0, 30 and 50vol%) were produced with the aim of increasing the tribochemical resistance in the machining of steels. Tool wear was related to the linear increase of the main cutting force (F_c) with time (dF_c/dt); a real-time parameter that can be used to assess the cutting edge damage and to stop machining before the tool fails. For all machined steels, tool wear resistance increased with increasing Al₂O₃ platelet content.     

Sustainability analyses of cutting edge radius on specific cutting energy and surface finish in side milling processes

The aim of this work is to determine the influence of cutting edge radius on the specific cutting energy and surface finish in a mechanical machining process. This was achieved by assessing the direct electrical energy demand during side milling of aluminium AW6082-T6 alloy and AISI 1018 steel in a dry cutting environment using three different cutting tool inserts. The specific energy coefficient was evaluated as an index of the sustainable milling process. The surface finish of the machined parts was also investigated after machining. It was observed that machining with the 48.50-μm cutting edge radius insert resulted in lower specific cutting energy requirements when compared with the 68.50 and 98.72-μm cutting edge radii inserts, respectively. However, as the ratio of the undeformed chip thickness to cutting edge radius is less than 1, the surface roughness increases. The surface roughness values gradually decrease as the ratio of undeformed chip thickness to cutting edge radius (h/r _e) tends to be 1 and at minimum surface roughness values when the ratio of h/r _e equalled to 1. However, the surface roughness values increased as h/r _e becomes higher than 1. This machining strategy further elucidates the black box and trade-offs of ploughing and rubbing characteristics of micro machining and optimization strategy for minimum energy and sustainable manufacture.     

Contrast in the transmission mode of a low-voltage scanning electron microscope

The contrast thicknesses (x_k) of thin carbon and platinum films have been measured in the transmission mode of a low-voltage scanning electron microscope for apertures of 40 and 100 mrad and electron energies (E) between 1 and 30 keV. The measured values overlap with those previously measured for E (≥ 17keV) in a transmission electron microscope. Differences in the decrease of x_k with decreasing E between carbon and platinum agree with Wentzel-Kramer-Brillouin calculations of the elastic cross-sections. Knowing the value of x_k allows the exponential decrease ∝ exp(—x/x_k) in transmission with increasing mass-thickness (x = ρt) of the specimen and the increasing gain of contrast for stained biological sections with decreasing electron energy to be calculated for brightfield and darkfield modes.     

A simple method for determining the extinction ratio of strongly scattering media

In order to determine the extinction ratio k of strongly scattering media, a simple technique for instrumental elimination of the initial curvilinear part of the dependence of optical density D on medium thickness h, D(h) = D ₁ + kh, where D ₁ is the apparent optical density of the surface layers of depth h _c = 1/k (1/k is the depth of radiation penetration into the substance), is proposed. To this end, two-beam recording is used, with the sample of thickness h placed in the working cell and with the shield of thickness h ₀, made of the same material, placed in the comparison cell, provided that h _c < h ₀ < h. The extinction ratio is found from the relation k = dD/dh, where dD = D(h)-D(h ₀) is the difference of the optical densities in the working cell and in the comparison cell and dh = h-h ₀ is the difference of the thicknesses. For samples with h < h _c, two shields of thickness h ₀ are placed in each cell (in the working cell, in front of the sample and behind it) provided that h ₀ > h _c. In this case, k = dD/h, where dD = D(h + 2h ₀)-D(2h ₀).     

CFD analysis of the performance of elbow-meter with high concentration coal ash slurries

Elbow meter is a simple flow measuring device and its characteristics for the flow of single-phase fluids are reasonably well understood and the functional dependence of elbow meter coefficient (C_k) on parameters like Reynolds Number, radius ratio, pipe roughness etc. Is well documented in literature. Elbow meters are also being used for solid liquid flow in many industries. The present study aims to establish the characteristics of an elbow meter for high concentration coal ash slurry pipelines using validated CFD. High concentration coal ash slurries are known to behave as homogeneous fluids exhibiting behavior as Bingham plastic fluids. The validated CFD methodology has been used to predict the values of C_k for the flow of Bingham plastic fluid and establish its dependence on radius ratio, Hedstrom Number and Bingham Reynolds Number. Further, for the flow of high concentration fly ash slurry flows, C_k for any given radius ratio is observed to be independent of Hedstrom Number (over the range investigated He ≤ 10⁵). Further, in fully turbulent flows, beyond a critical Reynolds number (Re_B ≥ 5.3 × 10³), C_k remains constant and is dependent only on the radius ratio.     

Influence of nozzle exit tip thickness on the performance and flow field of jet pump

The influence of exit tip thickness of nozzle δ _e on the flow field and performance of a jet pump was studied numerically in this paper. It is found that δ _e has influence on the distribution of turbulence kinetic energy k. If δ _e is ignored, k takes the highest value but dissipates rapidly than that of nozzle with a certain tip thickness. δ _e also affect apparently the development of tip vortex, which will occur near the exit tip of nozzle. The bigger the δ _e is, the larger the vortex is. The tip vortex develops with the increase of flow rate ratio q. When q=1 and δ _e =0.6∼0.8mm, a small vortex will be found downstream the tip vortex. And a concomitant vortex happens down the tip vortex in the case of q=1 and δ _e =0.8mm. As q increases to 2, the downstream small vortex disappears and the concomitant vortex becomes bigger. It is also found that the tip vortex might interact with the possible backflow that formed in the throat tube and parts of suction chamber. The center of backflow was affect evidently by δ _e . With the increase of δ _e , the center of backflow under the same q will go downstream. When δ _e =0.4mm, the center of backflow goes farthest. Then, as the further increase of δ _e , the center of backflow will go back some distance. Although, δ _e has relatively great influence on the flow field within the jet pump, it exerts only a little impact on the performance of jet pump. When δ _e =0.2∼0.6mm, the jet pump possess better performance. In most case, it is reasonable to ignore the nozzle exit tip thickness in performance prediction for the purpose of simplicity. This paper was presented at the 9^th Asian International Conference on Fluid Machinery (AICFM9), Jeju, Korea, October 16–19, 2007.     

Toroidal versus ball nose and flat bottom end mills

This paper compares the surface roughness along and across the feed directions produced by toroidal, ball nose, and flat bottom end mills. The study is conducted numerically and by cutting tests of aluminium. The results show that the toroidal cutter inherits the merits of the other two cutters; it produces small scallops across the feed direction, and low roughness along the feed direction.Nomenclature h scallop height - R _s radius of curvature of surface - inclination angle - 2a _c cross-feed - 2 subtended angle between the point of contact on the tool profile and the surface - R _a surface roughness - e offset distance of insert from tool axes for toroidal cutter - r _c cutter radius - r _i radius of insert for toroidal cutter - f _t feed per tooth - h _u undercut height - y, , intermediate variables     

New inverse gas chromatographic methodology for studying mass transfer caused by the evaporation of volatile liquids

Abstract

Physico-chemical quantities related to evaporation have been simply and directly calculated by a new methodology of reversed-flow inverse gas chromatography. The only demand is a preliminary determination of quantification coefficient(s), converting the signal to solute(s) molar or volume units. Time-dependent, k_c(t) and overall mass transfer, k_c, coefficients were determined for the evaporation of methanol at temperatures from 305 to 336 K, using two diffusion column lengths (10.0 and 40.5 cm) to evaluate the effect of the mass transfer route. Mass transfer coefficients indicate the endothermic nature of evaporation, while the longer diffusion route resulted in lower k_c values. The precision in the determination of evaporation rates was high (98.3%). Time-resolved diffusion coefficients, D_g(t), were also estimated. The smaller diffusion route resulted in lower values due to the higher enrichment of the mobile phase in the solute vapors. In the case of the smaller diffusion route, the change of D_g(t) values increased from 0.1% to 0.8%, while in the longer it was less than 0.1%. The respective temperature exponent increased with the diffusion route length from 1.68 to 1.74. Removing the effect caused by the different lengths of diffusion routes, the activation energy corresponding to pure evaporation was equal to 35.2 kJ mol^?1, rather close to the literature values for methanol’s vaporization enthalpy, indicating the reliability of the new methodology. Finally, the effect of mass transfer route was estimated to be 229 MJ mol^?1 km^?1, revealing the huge amounts of heat transfer accompanying evaporation at high altitudes.     

Elliptic feature of coherent fine scale eddies in turbulent channel flows

Direct numerical simulations (DNS) of turbulent channel flows up to Reτ=1270 are performed to investigate an elliptic feature and strain rate field on cross sections of coherent fine scale eddies (CFSEs) in wall turbulence. From DNS results, the CFSEs are educed and the strain rate field around the eddy is analyzed statistically. The principal strain rates (i.e. eigenvalues of the strain rate tensor) at the CFSE centers are scaled by the Kolmogorov length ηand velocity u_k. The most expected maximum (stretching) and minimum (compressing) eigenvalues at the CFSE centers are independent of the Reynolds number in each y⁺ region (i. e. near-wall, logarithmic and wake regions). The elliptic feature of the CFSE is observed in the distribution of phase-averaged azimuthal velocity on a plane perpendicular to the rotating axis of the CFSE (ω _c ). Except near the wall, phase-averaged maximum (γ^*/γ) and minimum (α^*/a_c ^*) eigenvalues show maxima on the major axis around the CFSE and minima on the minor axis near the CFSE center. This results in high energy dissipation rate around the CFSE.     

Seal-Inlet Disturbance Boundary Condition Correlations for Rotordynamics Models,Part 1: Correlation Development

Systematic parametric studies were performed to better understand seal-inlet rotordynamics. A CFD-perturbation model was employed to compute the seal-inlet flow disturbance quantities. Seal inlet disturbance boundary condition correlations were proposed from the computed seal-inlet quantities using the important parameters. It was found that the cosine component of the seal-inlet swirl velocity disturbance W _1C has a substantial impact on cross-coupled stiffness, and that the correlations for W _1C and W _1S should be used to replace the historical guess that seal inlet W _1C = 0 and W _1S = 0. Also, an extremely precise relationship was found between the cross-coupled stiffness and the seal-inlet swirl velocity (ω R _sh ?[Wbar] ₀ ). Thus, the number of experiments or computer runs needed to determine the effect of spin speed, shaft radius, and/or inlet swirl velocity on cross-coupled stiffness could be greatly reduced by plotting the simplified relationship of the cross-coupled stiffness against the swirl slip velocity. In addition, the upstream chamber size and shape were found to have a substantial influence on the seal-inlet swirl disturbance velocity W _1S which plays a significant role in determining the direct stiffness.     

Performance and surface alloying characteristics of Cu–Cr and Cu–Mo powder metal tool electrodes in electrical discharge machining

The main objective of this study is to investigate the effect of Cu–Cr and Cu–Mo powder metal (PM) tool electrodes on electrical discharge machining (EDM) performance outputs. The EDM performance measures used in the study are material removal rate (MRR), tool electrode wear rate (EWR), average workpiece surface roughness (R_a), machined workpiece surface hardness, abrasive wear resistance, corrosion resistance, and workpiece alloyed layer depth and composition. The EDM performance of Cu–Cr and Cu–Mo PM electrodes produced at three different mixing ratios (15, 25, and 35 wt% Cr or Mo), compacting pressures (P_c = 600, 700, and 800 MPa), and sintering temperatures (T_s = 800, 850, and 900 °C) are compared with those machined with electrolytic Cu and Cu PM electrodes when machining SAE 1040 steel workpiece. Analyses revealed that tool materials were deposited as a layer over the work surface yielding high surface hardness, strong abrasion, and corrosion resistance. Moreover, the mixing ratio, P_c, and T_s affect the MRR, EWR, and R_a values.     

Development and application of an ultra-precision lathe

This paper deals with the detailed development of an ultraprecision lathe for the purpose of machining magnetic disks. The rotational and feed accuracy and stiffness of the air bearing and the air slide were tested, respectively. A microcutting device using a piezoelectric material was also developed in order to maintain a uniform and precise depth of cut. Experiments machining a magnetic disk were carried out.Nomenclature A [m²] Area of piezoelectric actuator - C _o [mF] Capacitance of PZT - d ₃₃ [m V^–1] Piezoelectric constant - K _f [N V^–1] Equivalent force constant - K _m [N m^–1] Coefficient of force feedback - k _h [N m^–1] Stiffness of hinge - l [m] Length of PZT - M [kg] Mass of PZT system - r [mm] Radius of notch - U [m] Displacement of piezoelectric - ₃ [F m^–1] Dielectric constant of PZT - b [mm] Width of hinge - D _e [N s^–1] Equivalent damping coefficient - F _l [N] External load - K _e [N m^–1] Equivalent stiffness of PZT - k [m² N^–1] Elastic compliance of PZT - L [mm] Distance between hinge holes - M _e [kg] Equivalent mass of PZT - R _o [W] Output impedance of amp. - t [mm] Thickness between hinge holes - V _i [V] Input voltage - [g cm^–3] Density of PZT     

Numerical simulation of the transient cavitating turbulent flows around the Clark-Y hydrofoil using modified partially averaged Navier-Stokes method

This paper presents the implementation and assessment of a modified Partially averaged Navier-Stokes (PANS) turbulence model which can successfully predict the transient cavitating turbulent flows. The proposed model treats the standard k-ε model as the parent model, and its main distinctive features are to (1) formulate the unresolved-to-total kinetic energy ratio (f _k ) based on the local grid size as well as turbulence length scale, and (2) vary the f _k -field both in space and time. Numerical simulation used the modified PANS model for the sheet/cloud cavitating flows around a three-dimensional Clark-Y hydrofoil. The available experimental data and calculations of the standard k-ε model, the f _k = 0.8 PANS model, the f _k = 0.5 PANS model are also provided for comparisons. The results show that the modified PANS model accurately captures the transient cavitation features as observed in experiments, namely, the attached sheet cavity grows in the flow direction until to a maximum length and then it breaks into a highly turbulent cloud cavity with three-dimensional structures in nature. Time-averaged drag/lift coefficients together with the streamwise velocity profiles predicted by the proposed model are in good agreement with the experimental data, and improvements are shown when compared with results of the standard k-ε model, the f _k = 0.8 PANS model and the f _k = 0.5 PANS model. Overall, the modified PANS model shows its encouraging capability of predicting the transient cavitating turbulent flows.