Nozzle Exit Diameter Research Articles

Modeling of flow behaviour in a LD vessel by an impinging gas jet

Present study is focused towards development of computational fluid dynamic model of oxygen impingement in the melt pool in case of LD (basic oxygen converter) steelmaking process. 1/30th scaled down model of the 100 ton LD converter has been developed and flow simulation has been performed based on volume of fluid technique, using Fluent as solver engine. Simulation of the steel bath and oxygen is carried out by using water and air, respectively. Effect of process variables on the LD steelmaking practice has been studied and the findings ascertain penetration depth of the oxygen jet into the liquid (metal) pool as a strong function of bath (lance) height, gas flow rate and nozzle exit diameter. Furthermore, an equation is developed by carrying out regression analysis using results obtained from numerical simulation. The study also provides insight into the surface deformation modes, their onsets and transition regimes, which originates due to the gas impingement into the melt pool. Finally, the computed results are compared with the experimental findings for selected cases and good agreement has been found.

Study on Acoustic Prediction and Reduction of Epsilon Launch Vehicle at Liftoff

Subscale model tests and a numerical investigation are performed to predict and attenuate the acoustic level of the Epsilon launch vehicle at liftoff. Requirements for the subscale model test to predict a full-scale acoustic environment are investigated, and then the scale size of the model test is set at 1/42. The launch pads employed herein are designed to attenuate reflection of the Mach wave radiated from the free jet and the acoustic wave due to the jet’s impinging on the flame deflector. When comparing the acoustic result taken at the fairing location with that at three different altitudes, , , and , where represents the nozzle exit diameter, the acoustic level observed at is the highest and exceeds the design requirement at all frequencies. It is revealed from the numerical analysis that the reflection of Mach waves radiating from the free jet within the flame path is the dominant acoustic source. A front cover is attached to the vertical flame path to shield the Mach wave radiation, and 3 dB attenuation in the overall sound pressure level is achieved. The design methods and the knowledge obtained in this study are valid for the design of the launch pad to attenuate liftoff acoustics.

Output Flow Determination of Reverse Flow Diverters in Reverse Flow Mode Based on Pressure Data

The key fluidic component of a pneumatic pulse jet pump is a reverse flow diverter (RFD), which consists of a driving nozzle and diffuser, with a suction gap separating the two. Because the suction gap is open to the storage tank, the mass flow through a RFD is not constant, and it is difficult to determine its pumping capacity in the reverse flow mode. For symmetrical RFDs, we experimentally investigated the effects of the driving nozzle exit diameter d0, suction gap length dc, liquid viscosity μ, and pipeline load impedance on the RFDs’ performance in the reverse flow mode. A dimensionless performance curve insensitive to d0, dc, μ, and the pipeline load impedance was found based on these experimental data. The output flows of RFDs with suction factors higher than 0.9 could be determined using this dimensionless performance curve.

Hot-Flow Simulation of Aeroacoustics and Suppression by Water Injection During Rocket Liftoff

A scaled-down model experimental setup that exactly replicates a launch vehicle and launch pad for simulating the vehicle liftoff is tested for its aeroacoustic environment. The rocket exhaust consists of twin supersonic hot-air jets of Mach number 3.38. The role of shock noise is investigated in separate single-nozzle freejet and impinging-jet experiments with varying levels of overexpansion. The launch jet noise is suppressed by water jet injection into the exhaust plume for selected locations on the launch pad. Sound reduction up to 9 dB is achieved, and noise suppression continues to be effective up to of vehicle altitude ( being the nozzle-exit diameter). The sound spectra continuously varies from that of impinging jets at the deflector duct and launch table to that of freejets, as the vehicle is lifting off. The noise sources in heated jets respond similar to those in the cold jet, but comparatively higher sound reduction levels are obtained for hot jets in the impinging flow phase of liftoff (less than ). Varying the water injection pressure and mass flow rate show optimal conditions for noise suppression. Injecting water close to the nozzle exit effectively suppresses noise during vehicle liftoff.

Supersonic Jet Impingement on a Cylinder and Characterization of the Resulting Deflected Jets

The interaction between a mildly underexpanded supersonic jet and a single cylinder was studied experimentally at laboratory scale by using the schlieren technique coupled with high-speed photography and pitot pressure measurements. This study was motivated by the need to optimize sootblowing operation in kraft recovery boilers. The effects of the transverse distance between the jet and cylinder centerlines (eccentricity), nozzle–cylinder distance, and cylinder size on jet–cylinder interaction were determined. Results show that upon impingement on a cylinder, a supersonic jet deflects at an angle and creates a weaker supersonic jet that we refer to as a “secondary” jet. The angle and strength of the deflected or secondary jet depend on the eccentricity between the primary jet and cylinder centerlines. When a jet impinges on a cylinder of diameter comparable to that of the jet or smaller, secondary jets form not only when the cylinder is placed close to the nozzle (in the stronger portion of the jet) but also when the cylinder is placed far away (in the jet's weaker portion; up to 20–24 nozzle exit diameters in the present study). Changing the eccentricity slightly results in a significant change in the secondary jet characteristics. For a cylinder much larger than the jet, secondary jets do not form at zero eccentricity (head-on impingement); the eccentricity at which they begin to form increases with the cylinder size. A study of the secondary jets shows that they spread out much more than the primary jet and are sheet- or fan-like with an oblong, oval cross section. The centerline pitot pressure of the secondary jets remains as high as the primary jet for a considerable distance from the tube only during weak interaction between the primary jet and the cylinder (i.e., during strongly eccentric/off-centerd impingement). As the interaction between the primary jet and the cylinder intensifies at lower eccentricities, the maximum centerline pitot pressure of the secondary jet decreases, and the pitot pressure decreases more quickly with distance from the tube.

Heat Transfer Due to an Impinging Jet in a Confined Space

A numerical investigation using unsteady three-dimensional Reynolds-averaged Navier–Stokes (RANS) equations with the k-ω SST (shear stress transport) turbulent model was conducted to determine the flow and thermal characteristics of an unsubmerged axisymmetric oil jet in air, impinging normally on to a heated flat disk with finite radius, bounded by cylindrical walls kept at constant temperature. A 10 mm thick disk subjected to a high uniform heat flux was located at impingement distances ranging from 40 to 80 mm from the nozzle exit, for nozzle exit diameters of d = 1.0, 2.0, and 4.0 mm. The volume of fluid (VOF) method with a high-resolution interface-capturing (HRIC) scheme was implemented in STAR-CCM+. A new methodology was developed to predict the stagnation zone and local heat transfer coefficients. Contrary to previous research, it is shown that the radial extent of the stagnation zone is not fixed but depends on the gradient of radial velocity along the disk. The normalized local Nusselt number profile along the disk radius is found to be weakly dependent on Reynolds number for a given nozzle size. It is also shown that the local Nusselt number is not uniform in the stagnation region as reported by experimental studies but depends on the distribution of the near-wall radial velocity gradient. Using the computational results, new correlations to predict the dimensionless radial velocity gradient and Nusselt number have been developed. The present correlations are dimensionally balanced, eliminating a deficiency in earlier correlations noted in the literature.

Large-Eddy Simulations of a Single-Species Solid Rocket Booster Jet

This paper presents the results of large-eddy simulations of a solid rocket booster jet. An inert gas thermodynamically equivalent to the rocket exhaust is injected through the entire nozzle of the booster in the atmosphere at flight conditions of 20 km of altitude. A local time-stepping method via coupling multi-instances of a fluid solver is used to extend the computational domain up to 400 nozzle exit diameters. The mean flow and the turbulence statistics of the resulting supersonic coflowing jet are analyzed. The structure of the flow is identified, and important features show good agreement with other studies. In particular, the potential core length is consistent with previous analysis, whereas in the far field, the decay rate of axial velocity and the jet spreading rate are consistent with those of incompressible coflowing jets. Reynolds stresses profiles and turbulence scales, evaluated via two-point velocity correlations, are coherent with available data from high-speed jets. This study proves that the methodology applied for this single-species jet is efficient and reliable. Therefore, it can be directly used for large-eddy simulations of a booster jet that model the complex chemistry occurring in the plume.

Control of base pressure with micro jets for area ratio 2.4

This paper presents the results of experimental studies to control the base pressure from a convergent nozzle to ascertain the effect of level of expansion on a suddenly expanded sonic flow. An active control in the form of four micro jets of 1 mm orifice diameter located at 900 intervals along a pitch circle diameter of 1.3 times the nozzle exit diameter in the base region was employed to control the base pressure. The area ratio (ratio of area of suddenly expanded duct to nozzle exit area) studied is 2.4. Experiments were conducted for nozzle pressure ratio (NPR) from 1.5 to 3, in steps of 0.5. The length-to-diameter (L/D) ratio of the enlarged duct was varied from 10 to 1, and tests were conducted for L/D 10, 8, 6, 5, 4, 3, 2 and 1. It is evident from the results that the flow field downstream of the reattachment-redevelopment is very complex. It is found that, unlike in the case passive controls, the favourable pressure gradient does not ensure augmentation of the control effectiveness for active control in the form of micro jets. To study the influence of micro jets on the quality of flow in the enlarged duct wall pressure was measured and it is found that the micro jets do not disturb the flow field in the duct

Effect of Mach number on Wall Pressure Flow Field for Area Ratio 2.56

This paper presents the experimental results on the flow characteristics of a suddenly expanded flow from the convergent nozzle for subsonic flow. In the present study micro jets were used to investigate the effect of micro jets on wall pressure flow field in the enlarged duct. Accordingly an active control in the form of four micro jets of 1 mm orifice diameter located at 90 0 intervals along a pitch circle diameter of 1.3 times the nozzle exit diameter in the base region was employed. The Mach numbers of the present studies were M = 0.9, 0.8, and 0.6 and the area ratio (ratio of area of suddenly expanded duct to nozzle exit area) studied was 2.56. The length-to-diameter (i.e. L/D) ratio of the sudden expansion duct was varied from 10 to 1. From the results, it is seen that the flow in the base region is dominated by the waves, the general perception what we have that correctly expanded flow will be from waves is proved to be wrong; also, it is found that for L/D in the range L/D = 10 and 8 the flow remains oscillatory mostly for all the Mach numbers. However, these oscillations are suppressed gradually either with the increase in the L/D ratio in the range 3 to 6 or with decrease in the level of inertia level. The present study explicitly reveals that, the wall pressure in a suddenly expanded axi-symmetric duct can be controlled by employing micro jets. Since the flow field in the enlarged duct remained undisturbed hence, we can say that the control in the form of micro jets don't disturb the field.

Thruster Plume Surface Interactions: Applications for Spacecraft Landings on Planetary Bodies

Numerical and experimental investigations of supersonic jet interactions with a flat surface at various atmospheric pressures are presented in this paper. These studies were done in assessing the landing hazards of both the NASA Mars Science Laboratory and the Phoenix Mars spacecraft. Temporal and spatial ground pressure measurements in conjunction with numerical solutions at altitudes of nozzle exit diameters and jet expansion ratios between 0.02 and 100 are used. This study shows that, for typical landing spacecraft engine parameters, thruster plumes exhausting into Martian environments create the largest surface pressure loads and can occur at high spacecraft altitudes in contrast to the jet interactions, which occur in terrestrial and lunar atmospheres. These differences are dependent on the stability and dynamics of the plate shock, the length of the supersonic core, and plume decay due to shear layer instability, all of which are functions of the jet expansion ratio. Theoretical, experimental, and analytical results show that subscale supersonic cold gas jets adequately simulate the flowfield and loads due to rocket plume impingement, provided important scaling parameters are in agreement. These studies indicate the critical importance of testing and modeling plume–surface interactions for descent and ascent of spacecraft and launch vehicles.

Predictions of round impinging jet heat transfer with two k‐ω hybrid RANS/LES models

PurposeApplicability of two k‐ω hybrid RANS/LES and a k‐ω RANS models is studied for simulation of round impinging jets at nozzle‐plate distance H/D=2 with Reynolds number 70000, H/D=2 with Reynolds number 5000 and H/D=10 with Reynolds number 5000 (D is the nozzle exit diameter). The aim is to verify two concepts of unified hybrid RANS/LES formulations, one of DES (Detached Eddy Simulation) type and one of LNS (Limited Number Scales) type in analysis of impinging jet flow and heat transfer. The grid resolution requirements are also discussed.Design/methodology/approachThe simulations are performed with two k‐ω based hybrid RANS/LES models of very different nature, one of DES type and one of LNS type, and the RANS k‐ω model. For the lower Reynolds number (5000), also dynamic Smagorinsky LES is done. Both hybrid model formulations converge to the same RANS k‐ω model in the near‐wall region and have the same Smagorinsky limit on fine isotropic grids in the LES mode of the hybrid models.FindingsWith the hybrid RANS/LES models, improved fluid flow and heat transfer results are obtained compared to RANS, in the impact region and in the developing wall‐jet region. For accurate predictions at low nozzle‐plate distance, where the impact region is in the core of the jet, it is necessary to sufficiently resolve the formation and breakup of the near‐wall vortices in the jet impingement region and the developing wall‐jet region, as these determine largely the level of fluctuating velocity and the heat transfer. This requires high grid resolution for high Reynolds number, while the grid resolution requirements stay modest for low Reynolds number.Originality/valueThe paper demonstrates that two formulations of hybrid RANS/LES models of different nature, one of DES type and one of LES type, lead to equivalent results. Consistency has been guaranteed in the sense that the RANS limit of both models is the same and that the LES limit on fine, isotropic, grids is the same. In the intermediate range, however, the repartition into resolved and modelled fluctuations may differ considerably.

Study of Underexpanded Sonic Jets by Numerical Simulation

This paper deals with the numerical simulation of sonic underexpanded axi-symmetric jets, issuing from a convergent nozzle, at different nozzle pressure ratios. The simulations have been carried out by solving the unsteady Reynolds Average Navier-Stokes (RANS) equations utilizing the realizable k-ε (epsilon) two equations turbulence model in the commercial software FLUENT (version 6.3.26). The flow is assumed to be axi-symmetric and turbulent. The computational domain included a convergent nozzle of length 50 mm and a rectangular domain of size 25 times the nozzle exit diameter (D) verses 4D, which have been modeled and meshed in GAMBIT (version 2.46). The grid consisted of 81020 cells, while gradient grid adaptions were performed later to pronounce the accuracy of the results and visualize the shock-cell structures. From the simulations, it is inferred that, for correctly expanded jets, the potential core extends upto 6D, where D is the exit diameter of the nozzle. For underexpanded jets, the shock-cell structures in the jet flow field were captured properly. A pattern of ‘shock-diamonds’ or shock-cells were observed in the flow at low NPR. The formation of shock-cell is found to change considerably and also its strength increases with increase in nozzle pressure ratio (NPR). From this study, it is clear that the effect of favorable pressure gradient in the underexpanded jet influences the jet characteristics significantly. At high NPRs, ‘Mach disc’ formation is observed in the flow field. The flow after the Mach disc becomes subsonic and regains energy from the surrounding fluid.

Experimental and numerical investigation on the jet characteristics of spark ignition direct injection gaseous injector

Natural gas has widely been used as a fuel in conventional Diesel and spark ignition engines. The better understanding of injector parameters on the jet structure is helpful for the combustion optimization. This paper presents an experimental and numerical study on the jet structure of gaseous fuel injector in spark ignition direct injection engine by Schlieren technique and numerical procedure. Helium was injected through a gaseous injector at the different pressure ratios and nozzle diameters to understand the effects of nozzle geometry and pressure ratio for a dedicated correlation of CNG–SIDI injector. It was found that higher pressure ratio and exit nozzle diameter led to more tip penetration except the initial stages of jet development. Numerical simulation at the initial stage of jet development was not in exact agreement with experimental data due to transient effects of the needle lift within the injector tip and experimental errors while reliable results was observed after 1ms from the start of injection. It is also notable that tip angle of the jet did not have a specific trend when jet develops.

Drop Speeds from Drop-on-Demand Ink-Jet Print Heads

Measured drop speeds from a range of industrial drop-on-demand (DoD) ink-jet print head designs scale with the predictions of very simple physical models and results of numerical simulations. The main drop/jet speeds at a specified stand-off depend on fluid properties, nozzle exit diameter, and print head drive amplitude for fixed waveform timescales. Drop speeds from the Xaar, Spectra Dimatix, and MicroFab DoD print heads tested with (i) Newtonian, (ii) weakly elastic, and (iii) highly shear-thinning fluids all show a characteristic linear rise with drive voltage (setting) above an apparent threshold drive voltage. Jetting, simple modeling approaches, and numerical simulations of Newtonian fluids over the typical DoD printing range of surface tensions and viscosities were studied to determine how this threshold drive value and the slope of the characteristic linear rise depend on these fluid properties and nozzle exit area. The final speed is inversely proportional to the nozzle exit area, as expected from volume conservation. These results should assist specialist users in the development and optimization of DoD applications and print head design. For a given density, the drive threshold is determined primarily by viscosity η, and the constant of proportionality k linking speed with drive above a drive threshold becomes independent of viscosity and surface tension for more viscous DoD fluid jetting: <disp-formula id="jist4738ueqn1"> <mml:math overflow="scroll"> <mml:mi>F</mml:mi> <mml:mi>i</mml:mi> <mml:mi>n</mml:mi> <mml:mi>a</mml:mi> <mml:mi>l</mml:mi> <mml:mo>_</mml:mo> <mml:mi>s</mml:mi> <mml:mi>p</mml:mi> <mml:mi>e</mml:mi> <mml:mi>e</mml:mi> <mml:mi>d</mml:mi> <mml:mo>=</mml:mo> <mml:mi>k</mml:mi> <mml:mo>×</mml:mo> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>D</mml:mi> <mml:mi>r</mml:mi> <mml:mi>i</mml:mi> <mml:mi>v</mml:mi> <mml:mi>e</mml:mi> <mml:mo>−</mml:mo> <mml:mi>D</mml:mi> <mml:mi>r</mml:mi> <mml:mi>i</mml:mi> <mml:mi>v</mml:mi> <mml:mi>e</mml:mi> <mml:mo>_</mml:mo> <mml:mi>T</mml:mi> <mml:mi>h</mml:mi> <mml:mi>r</mml:mi> <mml:mi>e</mml:mi> <mml:mi>s</mml:mi> <mml:mi>h</mml:mi> <mml:mi>o</mml:mi> <mml:mi>l</mml:mi> <mml:mi>d</mml:mi> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>η</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> <mml:mo>)</mml:mo> </mml:mrow> <mml:mo>/</mml:mo> <mml:mi>N</mml:mi> <mml:mi>o</mml:mi> <mml:mi>z</mml:mi> <mml:mi>z</mml:mi> <mml:mi>l</mml:mi> <mml:mi>e</mml:mi> <mml:mo>_</mml:mo> <mml:mi>E</mml:mi> <mml:mi>x</mml:mi> <mml:mi>i</mml:mi> <mml:mi>t</mml:mi> <mml:mo>_</mml:mo> <mml:mi>A</mml:mi> <mml:mi>r</mml:mi> <mml:mi>e</mml:mi> <mml:mi>a</mml:mi> </mml:math> </disp-formula&gt

The impulse response of a high-speed jet forced with localized arc filament plasma actuators

We present experimental and theoretical analyses of the response of high-speed, high-Reynolds-number, round jets to impulsive forcing with arc-filament-plasma actuators. The impulse response is obtained with forcing Strouhal numbers, based on the nozzle exit diameter and exit center line velocity, less than 0.1. The resulting phase-averaged near-field pressure signature displays a compact wave with a positive peak preceding a negative one, indicative of a large scale structure in the shear layer of the jet. Scaling laws derived by operating the jet at four subsonic Mach numbers are used to distinguish this hydrodynamic component of the phase-averaged jet response from the direct actuator noise. As the forcing frequency increases, the compact waves in the near-field pressure signal overlap each other, indicating interaction of the growing seeded structures. For this regime, the phase-averaged response is approximately replicated by linear superposition of the impulse response, thereby demonstrating the quasi-linearity of structure interaction. A novel application of linear parabolized stability theory yields a successful model of the impulse response.

Preliminary study on deposition of aluminium and copper powders by cold spray micronozzle using helium

In general, the cold spray technique is applied for depositing coatings from powders of metals and alloys with 10–100μm particle size. A typical exit diameter of a cold spray axisymmetric nozzle ranges between 5 and 10mm that determines the spatial resolution of cold spray. Smaller nozzle exit diameters would provide a greater spatial resolution. In this study, micronozzles with 0.5mm throat diameter and 1mm exit diameter were applied for cold spraying aluminium and copper powders. Numerical simulation and experimental results on the application of micronozzles showed that fine (25μm and finer) aluminium and copper particles could be accelerated to their critical velocities. Aluminium and copper 1mm-width coatings were deposited.

Dimensionless performance and characteristic numbers of reverse flow diverters during reverse flow mode

ABSTRACTA reverse flow diverter (RFD) is a key fluidic component in RFD pumps, which are air‐powered, low‐maintenance devices used for transferring hazardous liquids. Despite several decades of practical application, no clear characteristic numbers exist for the suction ratio q = 1.0 and for the peak value of q, nor are there clear dimensionless performance curves for the reverse‐flow portion of the pumping cycle. We experimentally investigated the effects of suction gap length and nozzle exit diameter on RFD flow and pressure under the condition of diffuser entrance to nozzle exit area ratio of m = 1.0. The results were used to derive two dimensionless performance curves (q = A · exp[−δ/B] + C · exp[−δ/D] + E and q = k · α + F) and characteristic numbers at q = 1.0 and the peak value of q. These curves and numbers are useful to simplify the design program and ease the selection of operation parameters for RFD pumping systems. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.

New insights into retention aids dosage and mixing

Abstract In this work, critical design and operational parameters for retention aids dosage are studied through a combination of computational fluid dynamics (CFD), experimentation and pilot-scale production trials. In the first part of this work, three different retention aids dosage strategies are investigated in conjunction with pilot scale production trials. In all dosage strategies, a maximum in the percentage filler retention was observed at a speed ratio of 1.1, while considerably lower retention levels were observed when the speed ratio was greater than 2.2. However, the different dosage strategies led to markedly different retention of filler material. In the second part of this work, two-phase computational fluid dynamics (CFD) was used to model the three different dosage strategies implemented in the pilot production trials. The location and magnitude of maximum strain in each nozzle was determined and for each dosage case this was found to occur just outside the dosage nozzle at the point of impingement between the dosage and outer flows. In the third part of this work, conditions leading to the onset of retention polymer degradation were determined using an experimental flow loop. The effect of dosage speed and elongational strain created inside the dosage nozzle were studied systematically. These experiments showed that the effect of relative dosage velocity on polymer degradation was minimal. However, large levels of polymer degradation were observed when the elongational strain in the dosage nozzle was increased, i.e. when the exit nozzle diameter was decreased. Together, the three sets of experiments suggest that elongational strain during dosage degrades retention aids polymers and therefore hinders filler retention during production.

Modelling the Cutting Process and Cutting Performance in Abrasive Water jet Machining Using Genetic-Fuzzy Approach

Unconventional machining processes are used only when no other traditional machining process can meet the necessary requirements efficiently and economically. Abrasive Waterjet Machining (AWJM) is one of the most recently developed mechanical type unconventional hybrid manufacturing technologies. It is superior to many other cutting techniques in processing various materials, particularly in processing difficult to cut materials. This technology is being increase used in various industries. Therefore, optimum choice of the process parameters is essential for the economic, efficient, and effective utilization of these processes. Process parameters of AWJM are generally selected either based on the experience, and expertise of the operator or from the propriety machining handbooks. In most of the cases, selected parameters are conservative and far from the optimum. This hinders optimum utilization of the process capabilities. Selecting optimum values of process parameters without optimization requires elaborate experimentation which is costly, time consuming, and tedious. Process parameters optimization of AWJM essential for exploiting their potentials and capabilities to the fullest extent economically. This paper presents a Fuzzy Logic (FL) - based modeling of AWJM process and optimization of its rule base, data base and consequent part utilizing a Genetic Algorithm (GA). A binary coded GA has been used for the said purpose. While modeling with FL, the output parameters, namely Material Removal Rate (MRR) and Surface Finish (Ra) have been predicted for different combinations of process parameters, such as waterjet pressure at the nozzle exit diameter of abrasive-water jet nozzle traverse or feed rate of the nozzle mass flow rate of water and mass flow rate of abrasives between nozzle and the work piece.

Experimental and CFD Analysis on Coaxial Turbulent Jets with Different Velocity Ratios

Effects of nozzle pressure ratios on the coflow during mixing of circular supersonic inner jets with subsonic outer jets were experimentally studied for different area ratios such as 1.00, 1.25 and 1.76 (Aexit/Athroat). The same were numerically computed using CFD. The analyses for inner jet NPR values of 2.75 and 5 reveal that in downstream, the jet approaches symmetry at an axial distance of 1.7 times and 3.0 times the nozzle exit diameter. In circular coflow jet with different area ratios the dependence on the outer structures was also observed. At a greater NPR and area ratio the merging of the inner and outer flow occurs earlier in the downstream. Moreover an elongation in potential core length due to higher concentration of turbulent kinetic energy in the inner shear layer was established. Also, the experimental results of coaxial jets have good correlation with the CFD simulation. Overall, a greater area ratio nozzle exhibits distinct flow characteristics in mixing region. These flow characteristics produce more forceful mixing which is constructive and can be used effectively in combustion processes and propulsion applications.