Axial Intensities Research Articles

Quantitative ultrasonography reveals skeletal muscle abnormalities in carriers of DMD pathogenic variants.

Carriers of DMD pathogenic variants may become symptomatic and develop muscle-related manifestations. Despite that, few studies have attempted to characterize changes in the muscles of these carriers using imaging tools, particularly muscle ultrasound (MUS). The aim of this study was to compare lower limb MUS findings in carriers of DMD pathogenic variants (cDMD) vs healthy controls. Twenty-eight women (15 cDMD and 13 controls) underwent clinical evaluation and MUS. We collected information about muscle-related symptoms and assessed muscle strength. MUS was performed by a single physician (blind to the genetic status of subjects). The following muscles were assessed: rectus femoris, sartorius, tibialis anterior, and medial gastrocnemius. For each site, we computed data on muscle thickness, cross-sectional area, sound attenuation index, and elastography. Between-group comparisons were assessed using nonparametric tests and p-values <.05 were deemed significant. None of the subjects had objective muscle weakness, but exercise intolerance/fatigue was reported by four cDMDs and only one control. Regarding MUS, sound attenuation indices were significantly higher among carriers for all muscles tested. Longitudinal and axial deep echo intensities for the rectus femoris and tibialis anterior were also higher in the cDMD group compared with controls. No significant between-group differences were noted for elastography values, muscle area, or mean echo intensities. cDMD have skeletal muscle abnormalities that can be detected using quantitative MUS. Further studies are needed to determine whether such abnormalities are related to muscle symptoms in these patients.

Modeling and investigation of crack evaluation in metal tube based on magnetic field analysis method

In this paper, an analytical model of eddy current testing of a metal tube has been proposed to evaluate circumferential cracks from the signals of the magnetic field. First, based on Maxwell’s equations in time-harmonic form, magnetic vector potential equations for each region of space are built under two different configurations of the bobbin probe and the encircling probe respectively. Next, the magnetic vector potentials are solved by imposing conditions at the interface. Then, series expressions of the radical and axial magnetic induction intensities have been obtained. In addition, based on the proposed modeling, the influences of cracks at different locations on the surface magnetic field have been analyzed. The results have shown that the radial magnetic induction intensity increases while the axial magnetic induction intensity decreases for the internal and external cracks with the same shape and size on the surface of the metal tube. Moreover, the magnetic induction intensity has shown much more sensitive property to external cracks than it has done to internal cracks for the encircling probe. However, for the bobbin probe, the magnetic induction intensity has demonstrated almost the same sensitivity in detection for both internal and external cracks in the metal tube. The researching results have important theoretical and practical significance for understanding the physical process of eddy current testing, optimizing parameters of the experimental system and building the inversion model.

Dynamic Characteristics of Reconstituted Silt Influenced by Axial Unloading Intensity and Fine Particle Content

The stress disturbance induced by adjacent construction has a significant impact on the dynamic characteristics of the soil, resulting in complex long-term tunnel settlement under train vibration load. Through a series of dynamic triaxial tests, the effects of different fine particle contents and axial unloading intensities on the permanent axial deformation and excess pore water pressure of reconstituted silt under long-term cyclic loading were investigated. The findings show that as fine particle content in the silt increases, the threshold dynamic stress and failure cycle number decrease at first, then increase, reaching a minimum value at 10% fine particle content. The dynamic characteristics of silt are significantly affected by axial unloading, and the dynamic stress threshold amplitude of a soil sample decreases as the unloading strength increases. The accumulation of silt deformation caused by long-term cyclic load can be effectively controlled by ensuring drainage conditions.

Dissecting Electronic-Structural Transitions in the Nitrogenase MoFe Protein P-Cluster during Reduction.

The [8Fe-7S] P-cluster of nitrogenase MoFe protein mediates electron transfer from nitrogenase Fe protein during the catalytic production of ammonia. The P-cluster transitions between three oxidation states, PN, P+, P2+ of which PN↔P+ is critical to electron exchange in the nitrogenase complex during turnover. To dissect the steps in formation of P+ during electron transfer, photochemical reduction of MoFe protein at 231–263 K was used to trap formation of P+ intermediates for analysis by EPR. In complexes with CdS nanocrystals, illumination of MoFe protein led to reduction of the P-cluster P2+ that was coincident with formation of three distinct EPR signals: S = 1/2 axial and rhombic signals, and a high-spin S = 7/2 signal. Under dark annealing the axial and high-spin signal intensities declined, which coincided with an increase in the rhombic signal intensity. A fit of the time-dependent changes of the axial and high-spin signals to a reaction model demonstrates they are intermediates in the formation of the P-cluster P+ resting state and defines how spin-state transitions are coupled to changes in P-cluster oxidation state in MoFe protein during electron transfer.

A comparative study on PAH characteristics of ethanol and ammonia as fuel additives in a premixed flame

Due to issues towards polycyclic aromatic hydrocarbons (PAH) emissions and energy security, the renewable and non- or low-sooting tendency fuels are growing increased attention as alternatives to conventional fossil fuels. One feasible approach is to co-fire ethanol and ammonia with hydrocarbons, thus improving their combustion properties and pollutant emissions. This study presents a comparative study about the influence of ethanol and ammonia addition on PAH formation with the same blending ratios up to 30% by mole fraction in premixed C2H4 flames. The axial fluorescence intensities in three wavelength bands were measured to represent concentrations of 2- and 3-ring, 4-ring, 5-membered-ring aromatic species using the laser-induced fluorescence (LIF) technique. Experimental results indicated that both ethanol and ammonia addition could cause PAH reductions in premixed ethylene flames as their blending ratios increase. Further, ammonia was found more efficient than ethanol at inhibiting PAH formation under the same blending ratio. A chemical kinetic analysis was conducted to reveal the inhibiting role of ethanol and ammonia as substituents to ethylene on PAH formation. It was found that both ethanol and ammonia addition chemically suppress benzene formation and subsequent PAH growth due to the low yield of C2H2 and C3H3. Meantime, the additional C1 and C2 supply from ethanol decomposition could explain the relatively lower inhibiting effects on C6H6 and PAH formation as compared to the NH3 doped flames.

Effects of backward inclination on a pulsed jet in crossflow

The effects of the backward inclination angle on the flow and jet dispersion characteristics of a pulsed jet in crossflow were studied experimentally in an open-loop wind tunnel. The pulsations were created by a loudspeaker which installed at the bottom of a nozzle assembly. The instantaneous and time-averaged flow patterns were obtained using the laser-light sheet assisted smoke flow visualization method. The instantaneous and average velocities, turbulence intensities, integral turbulence time scales were probed using a hot-wire anemometer. The tracer-gas detection technique was applied to examine the fluid dispersion capability of the jet. With excitation, the axial jet pulsations were transferred to transverse oscillations after the jet was deflected by the crossflow. A small jet backward inclination angle could lead to an increase of jet-fluid dispersion and transverse jet spreading width. There existed a critical jet backward inclination angle of 20° at which the jet-fluid dispersion index and transverse jet spreading width attained the maximum values. Arranging the jet backward inclination angle at values smaller than 20° could induce an increase in dispersion of the pulsed jet in crossflow and benefit the industrial applications which required fast and efficient jet-fluid dispersion and mixing. • Jet backward inclination angle presented significant effects on axial mean velocities, turbulence intensities, and dispersion properties. • There existed a critical jet backward inclination angle of 20° at which the jet spreading width and dispersion attain maximum values. • At jet backward inclination angle smaller than critical value, increasing inclination angle could increase jet-fluid dispersion. • At jet backward inclination angle larger than critical value, increasing inclination angle would significantly decrease jet-fluid dispersion. • Arranging jet backward inclination angle at critical value could benefit industrial applications.

Quantitative Research on Cracks in Pipe Based on Magnetic Field Response Method of Eddy Current Testing

The quantitative evaluation of defects in eddy current testing is of great significance. Impedance analysis, as a traditional method, is adopted to determine defects in the conductor, however, it is not able to depict the shape, size and location of defects quantitatively. In order to obtain more obvious characteristic quantities and improve the ability of eddy current testing to detect defects, the study of cracks in metal pipes is carried out by utilizing the analysis method of three-dimensional magnetic field in present paper. The magnetic field components in the space near the crack are calculated numerically by using finite element analysis. The simulation results confirm that the monitoring of the crack change can be achieved by measuring the magnetic field at the arrangement positions. Besides, the quantitative relationships between the shape, length of the crack and the magnetic field components around the metal pipe are obtained. The results show that the axial and radial magnetic induction intensities are affected more significantly by the cross-section area of the crack. Bz demonstrates obvious advantages in analyzing quantitatively crack circumference length. Therefore, the response signal in the three-dimensional direction of the magnetic field gets to intuitively reflect the change of the defect parameter, which proves the effectiveness and practicability of this method.

Effects of Reynolds number on flow and mixing characteristics of a self-sustained swinging jet

The effects of Reynolds number on flow and mixing characteristics of a merged single swinging jet induced by a V-shaped fluidic oscillator were studied experimentally. The jet Reynolds number was varied from 80 to 3000. A high-speed digital camera was used to capture the instantaneous flow evolution processes using the laser light-sheet-assisted flow visualisation method. Long-exposure images together with the binary edge detection technique were used to identify the jet spread width. The velocities, turbulence intensities, as well as turbulence macro time and length scales in the central axis were measured using a one-component hot-wire anemometer. Measurement results using the tracer-gas concentration detection method provided information on the dispersion characteristics of the merged swinging and non-swinging jets. Four characteristic flow modes (non-swinging, subcritical swinging, critical swinging, and supercritical swinging jets) were identified within different ranges of jet Reynolds number. At Reynolds numbers <150 ± 10, no jet swinging happened. At Reynolds numbers between 150 ± 10 and 1200 ± 23, the instantaneous velocities of the merged jet presented periodic oscillations of small amplitudes and was denoted as the subcritical swinging jet. At Reynolds numbers between 1200 ± 23 and 2350 ± 50, the merged jet proceeded irregular swinging motion and was called the critical jet. At Reynolds numbers higher than 2350 ± 50, the time-evolving velocities of the merged jet presented periodic oscillations of large amplitudes imposed by large turbulent fluctuations and was termed the supercritical swinging jet. The measured results of the axial velocities and turbulence intensities in the central axis revealed that in the regime of the supercritical swinging jet, the momentum conversion from the axial to transverse direction was rapidly performed in the near field at the axial distance <2.4 times of the jet exit width due to the induced transverse jet oscillation. The transverse oscillations of the swinging jets induced large turbulence intensities and small turbulence macro time and length scales, and led to large jet mass dispersion. Therefore, the mixing characteristics of the flow was significantly improved due to large jet mass dispersion.

Influences of Excitation Current Frequency and Amplitude on Corrosion Evaluation Based on Analytical Model for Surface Magnetic Field

The influences of excitation current on the evaluation of the corrosion with a cylindrical shape in a semi-infinite plate are presented in this paper. First, axi-symmetric model of the cylindrical coil above the corroded plate is established and an analytical solution to the surface magnetic field is derived by means of the truncated region eigenfunction expansion method (TREE). Then, the effect of the excitation current frequency and amplitude on the surface magnetic field is investigated and quantitatively evaluated. It is found that the radial magnetic induction intensity increases as the excitation current frequency increases, whereas the axial magnetic induction intensity decreases. The excitation current amplitude is proportional to the radial and axial magnetic induction intensities and does not affect the phase of magnetic induction intensity. As a result, the influence node for detecting the radius and the hollow depth for detecting the hidden depth are obviously dependent on the excitation current frequency in terms of the butterfly-shaped graph. The calculation results are in good agreement with the numerical simulation, showing that the developed model can be used to predict the optimal excitation current frequency. This work indicates that an appropriate excitation current frequency, such as f = 500 Hz, can improve the characteristic parameter resolution for detecting the corrosion radius. For the detection of hidden depth, the lower excitation current frequency, such as f = 100 Hz, can amplify the defect phenomenon and improve the detection accuracy. It is not only helpful to develop the analytical model for the surface magnetic field, but also to optimise the parameters of the test device.

250 kHz three-component Doppler velocimetry at 32 simultaneous points: a new capability for high speed flows

Time-resolved Doppler global velocimetry (TRDGV) is used to demonstrate three-component velocity measurements of 32 planar points, acquired simultaneously at 250 kHz. Photomultiplier tube arrays are used to detect the flow signal, with each array having eight rows of four pixels. The system utilizes frequency scanning of a continuous wave laser, allowing for simple calibration of the signals used to determine the incident and Doppler-shifted frequency. The TRDGV system is used to measure an unheated, Mach 0.91 free jet downstream of the potential core collapse. Axial mean velocities were measured within a root-mean-square error of 7 m s−1 compared to Pitot probe validation measurements. Additionally, axial turbulence intensities showed agreement to hot wire validation measurements and exhibited typical magnitudes reported in the literature. Velocity spectra were obtained for the three components of velocity, revealing a − 5/3 decay in the axial velocity spectra in the inertial subrange frequencies, and generally less decay present in the transverse component spectra. Hot wire measurements and spectra from literature were used for validation of the TRDGV spectral results, showing broadband spectral agreement. The instrument described in this work shows promising capability for multi-point, time-resolved velocity vector measurement in high speed compressible flows with acceptable levels of uncertainty.

Effect of Particle Size and Surface Properties on the Sandbed Erosion with Water Flow in a Horizontal Pipe

Summary An experimental study was conducted to investigate the transport of sand particles over the sand bed deposited in a horizontal conduit by using turbulent flow of water. The main objectives were to determine the near-wall turbulence characteristics at the onset of bed erosion (i.e., near-wall velocity profile, Reynolds shear stresses, and axial-turbulent intensity); to determine critical velocity required for particle removal from the bed deposits; and more specifically, to determine how the sand-particle size and surface characteristics would influence the critical velocity required for the onset of bed erosion and the near-wall turbulence characteristics. A large-scale horizontal flow loop equipped with a nonintrusive laser-based particle-image velocimetry (PIV) system has been used for the experiments. The effect of sand-particle surface characteristics (i.e., wettability) on the critical velocity and the near-wall turbulence characteristics were investigated by using treated and untreated industrial sands of four different mesh sizes (i.e., 20/40, 30/50, 40/70, 100). The PIV technique was used to determine instantaneous local velocity distribution near the stationary sandbed fluid interface under subcritical and critical flow conditions. The near-wall velocity distribution measured directly at the sand bed/fluid interface together with the measured frictional pressure-loss values were then used for the evaluation of the Reynolds shear stresses and axial turbulent intensities acting at the bed/fluid interface. The results indicated that critical velocity for the onset of particle removal from sand beds increased with the increasing particle size. When sands with special surface treatment were used, it was observed that the critical velocity required for the onset of the bed erosion was significantly lower than that of required for the untreated sands. The degree of reduction in critical velocity varied between 14 and 40% depending on the particle size. In this study, by conducting experiments under controlled conditions, we provided much-needed fundamental data that can be used for the development of improved solid-transport design criteria and suitable mitigation technologies. In particular, we have shown the proof of concept that the surface-treated sand particles might have great potential for improving the transport efficiency of proppants used for hydraulic-fracturing operations.

Turbulence characteristics of a round offset jet with different offset ratios in a counterflow

A round jet entering a counterflow with different jet-to-current velocity ratios and different offset ratios was experimentally investigated using particle image velocimetry. Turbulence characteristics, including axial and radial turbulence intensity, Reynolds stress, and skewness in the radial direction, were analyzed based on the measured data. When a round free jet enters a counterflow, the axial or radial turbulence intensity increases to a maximum value rapidly after the jet exit and then generally decreases to a small value. Near the stagnation point, the axial turbulence intensity reaches a second local maximum value, while radial turbulence intensity does not appear the second local maximum value. The ratio of axial to radial turbulence intensity is 0.5 inside the penetration length. The axial and radial turbulence intensities do not present self-similarity in the radial direction. The skewness is negative on the axis, increases continuously as the radial distance increases, and reaches a maximum near the zero-velocity half-width and then gradually decreases. When an offset round jet enters a counterflow, the ratio of axial to radial turbulence intensity is less than 0.5 when the offset distance is less than 10D (where, D is the diameter of jet exit), while it is equal to 0.5 when the offset distance is greater than 10D. However, the other features of the jet are similar to that of a free jet entering a counterflow.

Electromagnetic Nondestructive Testing Model and Surface Magnetic Field Analysis for Circumferential Cracks on Metal Rod

AbstractIn this paper, an analytical model for a metal rod with a coating layer is proposed to evaluate circumferential crack from the signals of the surface magnetic field. In the proposed model, magnetic vector equations for four regions of space were built, and series expressions of the magnetic field were proposed by the truncated region eigenfunction method. The calculation results can show the three-dimensional distribution of axial and radial magnetic induction intensities on the surface of a metal rod clearly. In addition, the analytical model is verified by using comsol finite element simulation, which also demonstrates that induced eddy currents on the inner surface of the metal rod with cracks appear to be propelled toward the inner layer of the metal rod and the presence of a circumferential crack directly causes a decrease in the induced eddy current on the inner surface of the rod. The results calculated from the analytical model indicated that the model is capable of providing an accurate variation in the magnetic field due to circumferential cracks at different depths. The analytical results showed that the radial magnetic induction intensity increases by 0.16 × 10−3 T, while the axial magnetic induction intensity decreases by 0.3 × 10−3 T as the crack depth increases from 0 to 3 mm.

Flow and heat transfer characteristics of a pulsed jet impinging on a flat plate

The flow and heat transfer characteristics of a pulsed jet impinging on a flat plate under various excitation conditions were experimentally studied. The flow behaviors and time-averaged velocity fields of the characteristic flow structures were examined using a laser-assisted smoke flow visualization method and particle image velocimetry (PIV). The heat transfer of a pulsed impinging jet was measured by a thermal imaging camera. Two primary flow modes were observed in the domain of the jet pulsation intensity and excitation Strouhal number. The coherent vortices and vortex breakup modes appeared in the regimes of low and high jet pulsation intensities, respectively. In the coherent vortices mode, two submodes (contiguous vortices and discrete vortices) were additionally classified. The vortex ring maintained its coherency before impinging on the flat plate in the coherent vortices mode, while the vortex ring lost its coherency and broke up quickly before impinging on the flat plate in the vortex breakup mode. The increase rates of the axial traveling distance and axial convective velocity of the vortex rings in the vortex breakup mode were greater than those in the coherent vortices mode. Pulsating the impinging jet in vortex breakup mode, the effect of a large convective velocity of the vortex rings caused large mean axial velocities and axial velocity fluctuation intensities. The convective heat transfer was enhanced by increasing the convective velocity of the vortex ring and fluctuation intensity.

Attenuation Characteristics of Stress Wave Peak in Sandstone Subjected to Different Axial Stresses

To investigate the effect of axial stress on the attenuation characteristics of stress wave peaks, stress wave propagation experiments with small disturbance of a sandstone bar were carried out by a modified split Hopkinson pressure bar test system. Then, effects of axial stress on the waveform, attenuation rate, temporal-spatial attenuation characteristics, and attenuation sensitivity factor of the peak were studied. The results showed that the presence or absence of axial stress has a significant effect on the waveform. With axial stress loading, both temporal and spatial attenuation rates undergo similar development stages, “nonlinear stage + linear stage,” in which the demarcation stress (σ/σc) is 30%. Under the same axial stress, the peak decreases exponentially with the propagation time and distance with different attenuation intensities. With increasing axial stress, the temporal and spatial response intensities also experience “nonlinear stage + linear stage.” However, the temporal and spatial attenuation coefficients undergo three stages, first a dramatic decrease, then gentle development, and finally a sharp increase, in which demarcation stresses (σ/σc) are 30% and 55%. The defined attenuation sensitivity factor can well describe the attenuation sensitivity of peaks to different axial stresses. The conclusions can provide a theoretical reference for rock mass stability analysis in blasting excavation.

Experimental study on sudden contraction and split into the inlets of two parallel rectangular jets

The inlets to parallel rectangular jets are unique and a critical component of its design. A sudden contraction (contraction ratio = 4.2) of a vertically upward entry flow into two inlets has been investigated experimentally. Changes in velocity profile close to the inlets were measured, while the corner vortices, fluid separation and the development of axial and lateral turbulent intensities were observed from the result of particle image velocimetry analysis. The velocity profiles in the fluid adjacent to the inlets are independent of the Reynolds number, generally the same for similar geometries, concave but changes rapidly before finally adapting to the positions of the inlets. The radii of the corner vortices decreased and became elliptical with an increase in Re. Also, the detachment length shrunk by 60% when the Re was doubled. Lateral and axial turbulence increased and more fluid flowed parallel to the wall as Re increased. The trend and magnitude of the lateral to axial velocity agree with those of similar works.

Load response of the natural tooth and dental implant: A comparative biomechanics study.

PURPOSEWhile dental implants have displayed high success rates, poor mechanical fixation is a common complication, and their biomechanical response to occlusal loading remains poorly understood. This study aimed to develop and validate a computational model of a natural first premolar and a dental implant with matching crown morphology, and quantify their mechanical response to loading at the occlusal surface.MATERIALS AND METHODSA finite-element model of the stomatognathic system comprising the mandible, first premolar and periodontal ligament (PDL) was developed based on a natural human tooth, and a model of a dental implant of identical occlusal geometry was also created. Occlusal loading was simulated using point forces applied at seven landmarks on each crown. Model predictions were validated using strain gauge measurements acquired during loading of matched physical models of the tooth and implant assemblies.RESULTSFor the natural tooth, the maximum vonMises stress (6.4 MPa) and maximal principal strains at the mandible (1.8 mε, −1.7 mε) were lower than those observed at the prosthetic tooth (12.5 MPa, 3.2 mε, and −4.4 mε, respectively). As occlusal load was applied more bucally relative to the tooth central axis, stress and strain magnitudes increased.CONCLUSIONOcclusal loading of the natural tooth results in lower stress-strain magnitudes in the underlying alveolar bone than those associated with a dental implant of matched occlusal anatomy. The PDL may function to mitigate axial and bending stress intensities resulting from off-centered occlusal loads. The findings may be useful in dental implant design, restoration material selection, and surgical planning.

Turbulent Flow of Polymer Fluids Over the Sand Bed in Horizontal Concentric Annulus

Turbulent flow of non-Newtonian fluids over stationary sand bed deposits are commonly encountered during the wellbore clean-out operations conducted to remove the cuttings (solids deposited as a result of drilling or post-fracking operations) from the horizontal wellbore. We have investigated the impact of the presence of a stationary sand bed deposit on the characteristics of the flow in a horizontal concentric annulus using Particle Image Velocimetry (PIV)technique. Velocity profiles, Reynolds stresses, and axial turbulence intensities are measured in the lower and upper half of the annulus to assess the impact of the sand bed on the flow. Results show that the presence of the sand bed causes the reduction of the volumetric flow rate in the lower part of the annulus with an associated decrease in the local fluid velocity and the flow turbulence. In the upper part of the annulus, however, increased level of turbulence and flat velocity profiles were observed.

Flow Patterns and Heat Transfer in a Cylindrical Annulus under 1g and low-g Conditions: Theory and Simulation

A dielectric fluid is confined in a stationary vertical cylindrical annulus. A temperature difference is applied between the two cylinders, as well as an alternating electric potential. This configuration creates an active force called dielectrophoretic force, which acts as a thermal buoyancy force. Different axial gravity intensities are considered, so that two thermal buoyancies will affect the flow: the thermoelectric buoyancy intervenes in the radial direction and the Archimedean buoyancy acts in the axial direction. Linear stability analysis and direct numerical simulation are performed following experimental research that has been performed during parabolic flight campaigns.

Velocity fields and mixing properties of swirling double-concentric jets using two separated circular disks as center bodies

This study investigated the flow features, turbulence characteristics, and mixing properties of swirling double-concentric jets by using two separated circular disks as the center bodies. The upstream circular disk was placed at the exit of the central jet, while the downstream circular disk was located at a short distance downstream the upstream circular disk. The laser-assisted smoke-wire technique was used for flow visualization, particle image velocimetry (PIV) was utilized to investigate the velocity field, and the tracer gas concentration detection method was used to examine mixing property. When one circular disk was used as the center body, the flow patterns obtained through flow visualization and PIV measurement revealed two pairs of counter-rotating vortices existing in the near wake. The central jet penetrated the recirculation zone without any reversal, so low mixing between the central jet fluids and the annular swirling jet was observed. When two circular disks were used as the center body, the central jet momentum was transferred from the axial direction to the radial direction, and then it was dispersed and diffused into the annular swirling jet in the wake. Two flow modes were identified in the near wake: close-top toroidal wake and turbulent reverse-flow wake. In both characteristic flow modes, flows on the central axis were reversed in the near wake region. The axial and radial turbulence intensities were increased, and large values were observed inside the recirculation zone. Consequently, the carbon dioxide released from the central jet exit detected in the wake of the two-disk case was drastically lower than that of the one-disk case. The maximum improvement of mixing capabilities of the swirling double-concentric jets could attain about 96% when one circular disk was replaced by two disks.