Fluid Dynamic Characteristics Research Articles

In-vitro and particle image velocimetry studies of dry powder inhalers.

Inhalation drug delivery has seen a swift rise in the use of dry powder inhalers (DPIs) to treat chronic respiratory conditions. However, universal adoption of DPIs has been restrained due to their low efficiencies and significant drug losses in the mouth-throat region. Aerosol efficiency of DPIs is closely related to the fluid-dynamics characteristics of the inhalation flow generated from the devices, which in turn are influenced by the device design. In-vitro and particle image velocimetry (PIV) have been used in this study to assess the aerosol performance of a model carrier formulation delivered by DPI devices and to investigate their flow characteristics. Four DPI device models, with modification to their tangential inlets and addition of a grid, have been explored. Similar aerosol performances were observed for all four device models, with FPF larger than 50%, indicating desirable lung deposition. A high swirling and recirculating jet-flow emerging from the mouthpiece of the DPI models without the grid was observed, which contributed to particle deposition in the throat. DPI models where the grid was present showed a straightened outflow without undesired lateral spreading, that reduced particle deposition in the throat and mass retention in the device. These findings demonstrate that PIV measurements strengthen in-vitro evaluation and can be jointly used to develop high-performance DPIs.

Experimental and Numerical Investigation of the Influence of Leading Edge Tubercles on S823 Airfoil Behavior

Investigating the role of leading edge tubercles on the aerodynamic behavior of S823 airfoil tailored for wind turbine applications has been the forefront of the study. The aerodynamic characteristics of S823 airfoil effectuated by leading edge tubercles are ascertained at Reynolds number Re=200000 which is the usual operating range of most of the small-scale wind turbines. Firstly, the study elucidates the numerical investigation of baseline airfoil and later modified airfoils exhibiting different amplitude A and wavelength λ of the sinusoidal leading edge tubercles represented as A07W50, A12W50, and A07W25. The aerodynamic characteristics of the airfoils at Re=200000 and angles-of-attack ranging from 00 to 200 are evaluated numerically through k-ω SST turbulence model using ANSYS FLUENT® software package. A preliminary comparison of the computational data shows that the coefficient of lift Cl of all the modified airfoils was visibly superior to the baseline model across the angles tested. A07W50, A12W50 and A07W25 registered 20.6%, 26.2%, and 8.7% increase in the Cl values as compared to the baseline model. Contrasting to the Cl values, the aerodynamic efficiency Cl/Cd of the baseline model was slightly better but only across the pre-stall regime and later culminated with a sudden hard stall. Promisingly, this type of hard stall was not true for the tubercled models that demonstrated a more gradual and restrained stalling characteristic, thus showcasing superior performance in the post stall envelope that was never observed for the baseline model. Based on the outcomes, A07W50 model that displayed better aerodynamic characteristics was eventually fabricated and experimentally tested for its performance in a low speed wind tunnel. The numerical results of A07W50 were in good agreement with the experimental results. The overall results of the study prove beyond any point of doubt that tubercles indeed aid in improving the aerodynamic characteristics by enhancing the lift Coefficient Cl, rendering soft stalling nature and extending the scope of operation for the airfoil under study. Finally, the study positively confirms that leading edge tubercles very much play a significant role in passively augmenting the fluid dynamic characteristics of S823 airfoil and also qualify them to be a competitive passive flow control device.

Optimization and scale-up of ethanol production by a flocculent yeast using cashew apple juice as feedstock

Biofuels have been gaining more space in the global energy sector, with special attention to ethanol, which has shown growing demand. Ethanol is a potential and promising alternative fuel due to the use of abundant renewable sources and its combustion characteristics. From this scenario, this research aimed to optimize ethanol production by a flocculant Saccharomyces cerevisiae CCA008 using cashew apple juice (CAJ) as feedstock. The alcoholic fermentation of CAJ was influenced for all evaluated variables (inoculum and substrate concentration, temperature, and agitation) and statistical models were successfully applied to describe the interaction between these variables and to optimize the operating conditions. The optimum conditions were initial substrate concentration (S0) of 102 g L−1, inoculum concentration (X0) of 5 g L−1, temperature (T) and agitation (Agit) settings at 34 °C and 140 rpm, respectively. Last, but not least, the scale-up of ethanol production was carried out using the predicted optimum operating conditions, the fluid dynamics characteristics and applying the best scale-up criterion (power per unit of volume). The efficiencies of the processes (on bench and pilot-scale) were not significantly different and high efficiencies (96.6–98.2%) were achieved, demonstrating satisfactory results. Moreover, maximum ethanol concentration (Pmax), YP/S and productivity (QP) did not vary significatively when the process was scaled-up. On the pilot-scale, Pmax, YP/S and QP were 49.2 ± 2.2 g L−1, 0.493 ± 0.00 g g−1 and 5.0 ± 0.2 g L−1 h−1, respectively. Therefore, ethanol could be efficiently produced by the fermentation of CAJ using the flocculent yeast S. cerevisiae CCA008 and the process could be easily scaled up.

Research on the Dynamic Characteristics of Mechanical Seal under Different Extrusion Fault Degrees

In order to explore the dynamic characteristics of the mechanical seal under different fault degrees, this paper selected the upstream pumping mechanical seal as the object of study. The research established the rotating ring-fluid film-stationary ring 3D model, which was built to analyze the fault mechanism. To study extrusion fault mechanism and characteristics, different dynamic parameters were used in the analysis process. Theoretical analysis, numerical simulation, and comparison were conducted to study the relationship between the fault degree and dynamic characteristics. It is the first time to research the dynamic characteristics of mechanical seals in the specific extrusion fault. This paper proved feasibility and effectiveness of the new analysis method. The fluid film thickness and dynamic characteristics could reflect the degree of the extrusion fault. Results show that the fluid film pressure fluctuation tends to be more intensive under the serious extrusion fault condition. The extrusion fault is more likely to occur when the fluid film thickness is too large or too small. Results illustrate the opening force is affected with the fluid film lubrication status and seal extrusion fault degrees. The fluid film stiffness would not always increase with the rotating speed growth. The seal fault would occur with the increasing of rotating speeds, and the leakage growth fluctuations could reflect the fault degree.

EXPERIMENTAL EVALUATION OF PERFORMANCE AND MECHANICAL RELIABILITY FOR HIGH PRESSURE CO2 INTEGRALLY GEARED COMPRESSOR

Energy saving has become a trend as well as a countermeasure for global environmental issues. It can be one of the efficient solutions for reducing energy consumptions by adopting integrally geared compressors instead of inline compressors for industrial plants. The development of key technologies for the design centrifugal compressor such as CFD, FEM, Rotor dynamic Analysis has enabled integrally geared centrifugal compressors for higher pressure applications than ever. A commercial size, 5 stages integrally geared CO2 centrifugal compressor of 20MPaG discharge pressure level was designed, manufactured and evaluated the fluid dynamic performances and rotor stability. It was installed in OEM’s factory and the full load and full pressure test was carried out using real CO2 gas. The actual compressor fluid dynamic performance has shown superior results even at high pressure supercritical gas conditions at the high pressure stages of the compressor. The mechanical performances such as rotor vibration and bearing temperature were also measured and observed that the vibration was substantially low and within safe limits even at high pressure operating conditions above 20MPaG. Also the authors established a novel on Direct Rotor Excitation Method to experimentally investigate the rotor stability even at a high operating pressure level of 20MPaG. With this technique the measurements of the actual rotor natural frequencies and the damping ratios (log decrement) during high pressure operating conditions provided more precise results rather than conventional casing excitation method. The open impeller blade vibration was measured during running condition by using a non-contact blade vibration measurement technique. This measurement results revealed that impeller blades stress against the centrifugal force and the external excitation force was very low compared to the allowable stress value of the impeller material. The fluid dynamic characteristics and mechanical reliability are assessed as acceptable including super critical gas condition of CO2 gas.

Dynamic Analysis of a High-Pressure Relief Valve During Opening

Abstract In nuclear power plants, power actuated pressure relief valves serve several purposes. They act as safety valves and open automatically in response to unusually high pressures in the primary system. They also act as power-operated valves and are used to relieve steam in response to automatic or manually initiated control signals. These valves are required to lift completely over a short duration from the time that they receive an actuation signal, or the system pressure exceeds the set point. This short lift time results in the valve disk moving at high velocities, and can result in high impact forces on the piston and stem when the valve fully opens. To quantitatively evaluate the dynamic performance of the Target Rock Pressure Relief Valve, an analysis effort was undertaken which would accommodate both the fluid dynamic features of the valve operation, as well as the kinematic characteristics of the valve, during pressure relief valve operation. To execute the analysis, the Generalized Fluid System Simulation Program (GFSSP) was used. GFSSP is a network flow solver computational fluid dynamics (CFD) code developed by NASA that has the ability to analyze transient, multiphase flows, and conjugate heat transfer, along with the inclusion of custom user subroutines developed by the user which can accommodate other simulation requirements. In this paper, we present the GFSSP model developed, and the computed results that could be compared with corresponding parameters as measured from experimental testing for the pressure relief valve. Adjustments to GFSSP input parameters allow the anchoring of the GFSSP valve model to test data. This makes it possible to use the GFSSP model as a predictive tool for understanding valve dynamics, as well as evaluating proposed pressure relief valve modifications for performance improvements.

Numerical Simulations of the flow field within a 1:10 Aspect Ratio duct at intermediate Re

Numerical simulations are carried on to study the fluid-dynamical features of a smooth duct with aspect ratio of 10. The duct is operated with an incompressible, newtonian fluid, whose Reynolds number, computed over the hydraulic diameter and bulk velocity, ranges from 470 to 14500, encompassing laminar and turbulent flow. To capture the details of all the flow scales, Direct Numerical Simulations are performed, by means of a code developed at Politecnico di Milano. The adopted code is a finite-difference, structured grid solver, that includes a mass flow rate correction. The latter guarantees high accuracy in the calculation of unsteady flows, or during the transition to turbulent regime, and it allows to check the consistency of numerical results.Both global parameters –including the friction factor and the identification of the laminar-to-turbulent transition and local flow features, e.g., corner vortexes, are investigated and presented in this work. Preliminary analyses agree fairly well with literature data and with experimental results obtained at ThermALab of Politecnico di Milano.The final goal of this work, including a deep integration between the numerical and the experimental setup, is to carry on detailed investigations of the fluid-dynamical and thermal characteristics of ribbed ducts, in the perspective of heat transfer enhancement and pressure drop reduction.

High-Precision Dynamics Characteristic Modeling Method Research considering the Influence Factors of Hydropneumatic Suspension

In recent years, hydropneumatic suspension (HPS) has come into widespread use for improving the ride comfort and handling of mining dump trucks and off-road vehicles. Therefore, it is critical to improve the mathematical modeling accuracy to enhance the design and control efficiency and accuracy of HPS. This paper aims to propose a model for improving the modeling precision by considering the effect of different factors on HPS characteristics. A computational fluid dynamic (CFD) model of a HPS was developed, and the volume of fluid (VOF) method was used for the transient calculations in order to simulate the fluid dynamic characteristics and determine the damping and stiffness forces of HPS. The effect of temperature, oil viscosity, nitrogen dissolution rate, and suspension vibration speed on the nonlinear characteristics of HPS was investigated. A limited number of simulation sample points were designed based on the variation ranges of the above factors using the design of experiment (DOE) method. The corresponding damping and stiffness force of each sample point were calculated by CFD simulation. The obtained simulation data were utilized for the fitting of a Kriging model. The results demonstrated that the Kriging model can provide high accuracy, with a prediction error lower than 5%. The proposed modeling method of the HPS nonlinear characteristics is highly efficient, accurate, and faster than traditional methods.

LES study of unsteady cavitation characteristics of a 3-D hydrofoil with wavy leading edge

The present study seeks to conduct numerical investigations of the cavitating flow characteristics around a sinusoidal wavy leading edge (WLE) 3-D hydrofoil underlying a NACA 634–021 profile with an aspect ratio of 4.3. Cavitational and non-cavitational characteristics of hydrofoils are numerically examined at a chord-based Reynolds number of 7.2 × 105. The sinusoidal leading edge geometries include two WLE amplitudes of 5% and 25% and two WLE wavelengths of 25% and 50% of the mean chord length. We examined the cavitating flow around the hydrofoils in different cavitation numbers, namely σ = 0.8 and σ = 1.2. The flow over the protuberances of the WLE hydrofoil is considered at varying chord lengths and a constant angle of attack α = 6°, where significant spanwise variations in all flow properties, in contrast to the straight leading edge (SLE) hydrofoil, were observed. Large eddy simulation (LES) and Kunz mass transfer models are employed to simulate the dynamic and unsteady behavior of the cavitating flow. Besides, the compressive volume of fluid (VOF) method is used to track the cavity interface. Simulation is performed under the two-phase flow solver —interPhaseChangeFoam— of the OpenFOAM package. Compared to the SLE hydrofoil, we provided an exhaustive report of the time-averaged and instantaneous fluid dynamic characteristics of the cavitating flow around the sinusoidal leading edge hydrofoil, i.e., pressure, velocity, and vorticity fields, as well as lift and drag coefficients, and turbulent kinetic energy are reported. Furthermore, detailed analyses of the instantaneous cavity leading edge and flow separation treatment, vortical structure of the flow, vorticity stretching and dilatation, details of the spanwise flow, the formation of a low-pressure zone behind the WLE hydrofoil, streamwise velocity fluctuation, and evolution of the cavity dynamics through a complete cycle are reported. Results show that early development of the laminar separation bubble (LSBs) on the suction side of WLE hydrofoil prevents significant flow separation. Furthermore, the WLE cases exhibit a significantly reduced level of unsteady fluctuations in aerodynamic forces at the frequency of periodic vortex shedding.

The flow and mass transfer characteristics of concentric gas-liquid flow in an advanced static mixer

The fluid dynamic and mass transfer characteristics of concentric upward gas-liquid flow were studied in an industrial static mixer with four equally spaced helical inserts (FKSM). The numerical simulations of the gas volume fraction in a Kenics mixer was in good agreement with the numerical and experimental results provided by Rabha et al. The characteristics of radial gas void fraction and local mass transfer coefficients in the FKSM were evaluated under different operating conditions. The velocity profiles of the concentric air phase accelerated by the bubble forces first became sharp and narrow until z/l = = -3.27 and then slowly decreased and stabilized at z/l = -1.5 before entering the first mixing element. Some extra unimodal profile of radial gas holdup gradually generated near the rectangle cross-sections of the mixing elements. The ?G gradually enlarged from r/R = 0.2 to r/R = 0.55 and then weakened from r/R = 0.65 to r/R = 0.874. The air void fractions in the bulk flow region decreased with the increasing initial uniform bubble diameter. The inlet effect of the first leading edge enhanced the air phase dispersion and local mass transfer coefficients sharply increased from 2.04 to 3.69 times of that in the inlet. The local mass transfer coefficients in each mixing group had unimodal profiles.

Characteristics of pressure drop, mass flow distribution and flow asymmetry in three‐dimensional branching networks based on model human bronchial tree

AbstractThe complex flow field in the three‐dimensional internal passages of a model human bronchial tree is studied computationally. Up to five generations of branches, both in‐plane and out‐of‐plane configurations, two velocity profiles and varying inlet Reynolds number are considered. There exists substantial non‐uniformity of the fluid dynamic features (e.g. velocity field, pressure field, mass flow distribution or viscous dissipation) over any longitudinal plane or cross‐sectional plane of a particular branch as well as that between different branches of any generation. The flow asymmetry is explained here by attributing the fluid dynamics to three important features ‐ curvature of flow path, flow division at bifurcations and inertia of the flow. A synthesis of the present comprehensive study leads to the generalization that the out‐of‐plane configuration fosters greater degree of uniformity in the mass flow distributions in the various branches of any generation, but gives rise to greater flow non‐uniformity on any particular cross‐sectional plane as compared to the in‐plane configuration. The out‐of‐plane configuration also causes greater secondary flow and greater loss in total pressure in the network. The effectiveness of previously developed modular computational approaches is assessed through separate simulations for networks comprising two, three, four and five generations (containing 3, 7, 15 and 31 branches respectively). The inadequacy of Hagen‐Poiseuille type 1D model is demonstrated ‐ it can neither predict the flow asymmetry (captured by the 3D computations) nor determine the overall magnitude of loss in total pressure.

Effect of electrolyte convection velocity in the electrode on the performance of vanadium redox flow battery cells with serpentine flow fields

Sufficient convective velocity in the electrode is essential for the good performance of a flow battery. The present study is concerned with identifying how this condition is attainable for a given size of a vanadium redox flow battery cell. To this end, detailed experimental investigations of fluid dynamic and electrochemical characteristics with serpentine flow fields have been done in cells with active area of 416, 918 and 1495 cm2, and optimal operating conditions of reasonably high efficiency, discharge capacity and energy density have been identified for each size. Investigations using calibrated computational fluid dynamics simulations show that optimal performance condition for each cell size corresponds to the case where the local convective velocity in the electrode is the same and is of the order of Reynolds number ~2. Based on this condition, a model has been developed to determine the optimal electrolyte circulation rate for a given cell size and operating current density.

Upward Flame Spread and Extinction over Wavy Solids

ABSTRACT Laboratory scale experimental and modeling results of one-sided upward flame spread over wavy cellulosic paper samples are presented. The sinusoidal shaped samples with varying wavelength and amplitude are aligned perpendicular to the gravitational direction so the upward buoyant flow sees peaks and valleys along its flow path. Depending on the wave amplitude and wavelength, the flame can spread from sample peak to peak initially but may later sustain slow burning from isolated flamelets inside the sample valleys or become quenched. The degree of fuel burning completeness, pyrolysis front spread rate, and extinction limits (both local and overall) depend on the wavy parameters in a complex way as well as the ambient relative humidity. Flame spread over wavy samples thus has unique features not found in continuous flat samples nor in discrete samples. Video records of the experiments supplied in the paper present both the front and the side views of these interesting transient flame developments. A simplified two-dimensional numerical model was formulated and solved to show selected salient features of the complex fluid dynamics over wavy structure and the heat transfer and burning characteristics of the wavy samples.

NOVEL METHOD FOR ASSESSING PLATELET RESPONSE TO ADP: TECHNICAL VALIDATION STUDY OF THE AGGREGUIDE A-100 ADP ASSAY

The recently FDA approved AggreGuide A-100 ADP (A100ADP) assay includes appropriate fluid dynamic characteristics in a microfluidic reaction chamber with whole blood in motion to measure P2Y12 inhibitor effects. The ability of the A-100ADP assay to demonstrate P2Y12 inhibitor-induced platelet

A Numerical Investigation on Fluid Dynamics and Heating Characteristics of Co-and-Counterrotating Multiple Swirling Impinging Flames Arranged in 3 × 3 Inline Array

Abstract Swirling impinging flame jets possess the potential of uniformly heating the target surface. Numerical simulations have been carried out for multiple reacting swirling flows arranged in square 3 × 3 array. The turbulence chemistry interactions in the flow field are modeled using RNG based k-ε/ eddy dissipation model (EDM) framework. Co-and-counterrotating configurations have been compared for interactions and spent gas release mechanism at fixed inter-jet spacing and separation distance. Multiple swirling impinging flames undergo strong interactions resulting in distortions of recirculation zones (RCZs) for all the surrounding but central flame. Co-swirling flames result in development of higher turbulence in the interaction regions as compared with counter-swirl case. Tilted heat flux contours have been noticed for co-swirling impinging flames, whereas heat flux impressions are straight for counter-swirl case. Effect of inter-jet spacing (C/Dh = 5, 7, and 9) and separation distance (H/Dh = 3, 5, 7, and 9) studied for co-swirl case revealed that peak heat fluxes decreased with increasing inter-jet spacing and separation distance. With increase in inter-jet spacing, the width of central flame increased due to increased suppression effect induced by the recirculating gases. Increase in separation distance resulted in decrease of width of central flame and thermal dilution taking place led to decrease in heat flux magnitudes.

Studies on Separation Efficiency and Energy Conservation Through Novel Finned Cyclone Separator

Abstract In the present study, cylindrical portion of conventional (nonfinned) cyclone separator was reshaped by fixing triangular, semicircular, and rectangular cross section helical fins in order to make it as water wall having fin size 7 mm with fin pitch of 40 mm to improve its separation efficiency and to utilize the cyclone separator as heat exchanger. Fluid dynamic characteristics like axial velocity, tangential velocity, pressure drops were studied by varying the fin geometry (triangular/semicircular/rectangular). For the particles' size less than 3 μm, proposed cyclone separator with triangular helical fin was giving comparatively improved collection efficiency than other selected cyclone separators. Improvement in the collection efficiency of triangular fin-based cyclone separators was perceived from 5% to 10% over the conventional cyclone separator. Hence, helical fins with triangular in cross section were selected further for heat transfer and scale-up studies. It was observed that for the small barrel wall height (h = 400 mm) water temperature was enhanced by 4 °C, and with scale-up (making h = 800 mm) it was increased considerably around 15 °C. Thus based on improved separation efficiency to capture very-fine particulate matter (PM 2.5, which otherwise causes serious health issues) and considerable temperature gain of water noted at lab level scale-up study, triangular helical fins may be to fixed on the inner surface of barrel wall of conventional (nonfinned) cyclone separators in order to use them as heat exchanger for energy conservation in industrial applications.

A simulation model of Gerotor pumps considering fluid–structure interaction effects: Formulation and validation

Gerotors are compact, inexpensive and robust pumps generally used in hydraulic systems. Owing to their characteristic operation at low pressure (up to 30 bar), these units can be modelled using relatively simple tools considering only their fluid dynamics aspects. However, some commercially available Gerotors operate at higher pressures so that material deformation effects cannot be neglected under such conditions. This paper presents an omni-comprehensive simulation approach for Gerotor units that considers the fluid–structure interaction effects at the lateral lubricating gaps and related to the contacts between the rotors. The numerical tool consists of different submodels which allow the evaluation of the fluid dynamic features of the flow through the pump considering micro-motion effects of the rotors. This paper particularly details the novel aspects of the simulation approach, which is the introduction of submodels that account for fluid–structure interaction effects: the lateral lubricating gap models and the rotor contact models, both based on the solution of the Reynolds equation considering the deformation of the solid parts.For the model validation, a commercially available pump able to operate above 100 bar was tested at the authors’ research center. The comparison between the simulation results and the experimental data clearly show the good accuracy of the model, in terms of volumetric flow and port pressure pulsation. In particular, the model allows predicting both the volumetric and the torque efficiency of the unit. Furthermore, the simulation results permit to interpret the reasons for instances of wear present in the unit.

Effect of geometrical parameters on the fluid dynamics of air-powered needle-free jet injectors

Needle-free jet injectors are non-invasive systems having intradermal drug delivery capabilities. At present, they revolutionize the next phase of drug delivery and therapeutic applications in the medical industry. An efficiently designed injection chamber can reduce the energy consumption required to achieve the maximum penetration depth in skin tissue. In this study, the authors explored the effect of various geometrical parameters using a computational fluid dynamics tool. Peak stagnation pressure during the initial phase of the injection procedure was considered as the quantifier for comparison because of its proportional relationship with the initial penetration depth during the injection process. Peak stagnation pressure indicates the maximum energy transformation that could happen between the microjet and skin tissues for an injection procedure. The results of this study indicated a tradeoff that exists between the attainable density and velocity of the microjet on the skin surface with variation in nozzle diameter; the optimum nozzle diameter was found to be within 200–250 μm under the present conditions. The authors also observed a discrepancy in the peak stagnation pressure value for lower filling ratios with variation in chamber diameter; hence, filling ratio of at least 50% was recommended for such systems. Furthermore, a 150% increase in the peak stagnation pressure was obtained with an angle of entry of 10°. In general, this study could provide valuable insights into the effect of geometrical parameters in the fluid dynamics characteristics of propelled microjets from the nozzle of a needle-free jet injector. Such information could be useful for the design of a mechanically driven needle-free jet injector having limited control over the energizing mechanism.

Hydrodynamic characteristics of a 2D2D cyclone separator with a finned cylindrical body

Cyclone separators used for separating solid particles from the gases mainly employed in electricity generating units having fluidized bed boilers and in other industries such as cement industries. In the present study, cylindrical portion of the nonfinned (conventional) cyclone separator (nfcs) was reshaped by fixing triangular helical fins in order to improve its performance in terms of collection efficiency. Fluid dynamic characteristics like axial velocity, tangential velocity, pressure drops etc. were studied which influences the collection efficiency by varying the fin size (fs) such as 5.0 mm, 7.5 mm and 10.0 mm and also by varying fin pitch (fp) as 50.0 mm and 30.0 mm. With available experimental work, validation was accomplished for the nfsc before proceeding computational study on the novel triangular finned cyclone separators (fcs). For the particles' size less than 3 μm, comparatively proposed triangular fin with fs & fp as 7.5 mm & 30.0 mm respectively was giving improved collection efficiency than other selected separators. Improvement in the collection efficiency of triangular finned cyclone separators (fcs) was perceived from 5% to 10% over the conventional cyclone separator (nfcs). Main role of the cyclone separators is to separate the particles from gases which was unruffled after by inclusion of fins. Rather fin inclusion has played a dominant role in minimizing very fine particulate matter emissions which otherwise leads to severe health problems.

Study on instability of circular liquid jets at subcritical to supercritical conditions using dynamic mode decomposition

The thermodynamic and fluid-dynamic properties associated with the injectant jet significantly influence its fluid dynamic characteristics. In most of the earlier studies on the behavior of liquid jet at high pressure and supercritical environment, the liquid jet is often injected at subcritical initial temperature. In the present study, the effect of variation in the fluid and flow properties of the injecting jet on the nature of instabilities and mixing behavior is investigated. The fluid properties of the injected jet are varied by preheating. High-speed imaging techniques are used to capture the jet behavior. To gain further insight into the instability nature of the jet, linear instability analysis was performed. Dynamic mode decomposition analysis was applied to the obtained high-speed images to extract and understand the relevant dynamic features.