Effect Of Swirl Research Articles

Studies on the Effect of Swirl on Nitric-Oxide Formation in Combustion—a Selected Review

Studies on the Effect of Swirl on Nitric-Oxide Formation in Combustion—a Selected Review

Heat transfer characteristics of a high-pressure turbine under combined distorted hot-streak and residual swirl: an unsteady computational study

• Unsteady CFD simulations were performed for a transonic turbine stage to reveal the effects of uniform and swirled flows on hot-streak transport. • Two ideal hot-streak maps, radial and rounded, were evaluated against a realistic distorted hot-streak map. • The residual swirl contributed to the homogenisation of the radial hot-streak and the dispersion of the rounded and distorted hot-streaks through the rotor. • The distorted hot-streak showed the most complex transport behaviour through the stage. • The residual swirl was found to intensify the leakage vortex and increase the heat transfer rates near the tip region. In new generation aero-engines, lean-burn combustors are equipped with swirl injectors in order to reduce pollutant emissions. At the exit of these combustors, the flow is dominated by temperature non-uniformity (hot-streak) and residual swirl. Available research has focused mainly on the isolated effects of the residual swirl only or the hot-streak only on the aerodynamic performance or thermal performance of the high-pressure turbine (HPT). Only few studies investigated the combined swirl and hot-streak on the aerothermal performance of the HPT using either idealized uniform or rounded hot-streak topologies. Realistic hot-streaks generated from lean burn combustors have more complex topologies that involves distortions. The present study investigates the effects of residual swirl and distorted hot-streak simultaneously on a first stage of a HPT. Other hot-streak types, uniform and rounded, have been also investigated with and without swirl to perform comparisons with the distorted hot-streak. Unsteady Reynolds-averaged Navier–Stokes (URANS) computations have been conducted to assess the aerothermal performance of a HPT under the influence of different hot-streaks. Results revealed that all hot-streaks without swirl were almost preserved as transported through the vane and altered as transported through the rotor due to the secondary flows. Under the residual swirl, all hot-streaks were remarkably altered at the vane exit and deformed more at the rotor exit. The uniform hot-streak was homogenised through the rotor and the rounded and distorted hot-streaks were dispersed. The distorted hot-streak showed the most complex transport behaviour through the stage. Results also revealed that the leakage flow through the rotor tip gap generated high heat transfer rates, in particular on the rotor blade suction side and tip surface. The leakage flow formed the known leakage vortex at the tip gap exit, which induced high heat transfer rates. The residual swirl was found to intensify the leakage vortex and consequently higher heat transfer rates are generated compared to the uniform flow condition.

Azimuthal Instabilities of an Annular Combustor With Different Swirling Injectors

Abstract Experiments are carried out on the laboratory-scale MICCA-Spray annular combustor to examine the effects of swirlers on combustion instabilities. This system comprises 16 spray-swirl injectors and gives rise to instabilities coupled by azimuthal modes. Five types of swirlers producing clockwise rotation and varying in swirl numbers and pressure drops are considered. These swirlers can be broadly categorized into two groups: lower-swirl and higher-swirl groups, based on their swirl numbers. An arrangement where clockwise and counterclockwise swirlers alternate is also studied. Experiments are performed systematically with liquid heptane at five levels of thermal power and six equivalence ratios. Results reveal that none of the swirlers in the lower-swirl category exhibit instability in the operating region considered, whereas the higher-swirl units feature strong azimuthal instabilities that trace an overall limit cycle envelope with a few short and random bursts. Among the higher-swirl group, a higher pressure drop swirler is associated with a broader instability map. This shows that the transition to instability mainly depends on the swirl number through its effect on the flame structure and that the pressure drop adds to further variations in amplitude and frequency of oscillation. The spin ratio time series indicate that the modes are of mixed type and that their distribution depends on the operating condition. On specifically comparing the spin ratio distribution between a full set of clockwise rotating (CR) swirlers and a configuration where clockwise and counterclockwise rotating swirlers (CCR) are alternatively placed, it is found that there is no definite statistical preference for spin ratio linked to the effect of bulk swirl. In some cases, however, the CCR configuration promotes a broader distribution of spin ratios centered around the standing mode (sr = 0) while the CR setup favors azimuthal modes spinning in the counterclockwise direction. An attempt is made to interpret the occurrence of instabilities by making use of flame describing functions (FDFs) measured in a single-injector combustor. It is found that the FDFs corresponding to the two swirler categories (lower-swirl and higher-swirl) are relatively distinct. The observed behavior is tentatively interpreted using an instability analysis in which the injector and upstream plenum are represented by an impedance that shifts the band of instability. The unstable behavior is then linked to the relative position of the FDF phase with respect to the instability band in the frequency range corresponding to the expected azimuthal mode frequency. The phase and gain of the FDF notably depend on the swirl number, and it is possible to distinguish, for the present configuration, a category of low swirl number injectors inducing stable operation and another category of high swirl number units leading to oscillations.

Effect of Strong Azimuthal Swirl on Ignition and Light-Around in an Annular Combustor

Abstract In this paper, we investigate the effect of strong azimuthal swirl on ignition dynamics in a laboratory-scale annular combustor. Bulk azimuthal swirl was produced by a novel angled injector configuration, producing swirling jet flames oriented downwards toward the combustor backplane and in the azimuthal direction, replicating a simplified version of the SAFRAN spinning combustor concept. To provide more realistic flow conditions, the design included rich-quench-lean (RQL) staging via a circumferential distribution of dilution ports and an effusion cooled combustor backplane. High-speed imaging and an azimuthal array of photomultipliers to measure OH* chemiluminescence were used to characterize the ignition dynamics for different injector velocities and global equivalence ratios. The mass flows through the injectors, dilution ports, and effusion cooled backplane were independently metered so that the injector equivalence ratio and global equivalence ratio could be separately controlled. The light-around times were found to have no clear correlation with the injector velocity since the rich injector equivalence ratio meant the flame burned in a nonpremixed mode even though the global equivalence ratio was lean due to the RQL staging. However, it was found that lower injector velocities extended the lean ignition limit based on the global equivalence ratio. The ignition sequence during light-around (order in which the injectors are ignited) was found to be highly repeatable, igniting each consecutive injector in the anticlockwise direction (the direction of bulk swirl). In rare cases, the ignition sequence was observed to branch in both directions. Finally, in an effort to extend the lean ignition limit, the effect of azimuthal staging was investigated. Two configurations were tested. In the first configuration, the injectors on one half of the annulus were operated at a fixed equivalence ratio whereas the other half of the annulus was operated at a different equivalence ratio. In the second configuration, every second injector had the same equivalence ratio. Both configurations extended the lean extinction limit but the first configuration was the most effective.

How angular-momentum flux controls Francis turbine full-load surge

Hydropower plants equipped with Francis turbines may enter unstable conditions at high turbine discharge [13], with strong pulsations of power output and internal pressure. The cause are oscillations of a vapor-filled cavity in the vortex flow downstream of the turbine runner, interacting with the draft tube and penstock pressure. The paper describes the structure and simulation results of a 1D distributed-parameter model for full-load surge, parametrized from results of a high-resolution unsteady two-phase CFD simulation study (Wack [14]) of high-load pulsations in the reduced-scale model of a medium-specific speed Francis turbine. In earlier research on the same model turbine, Müller [12] had suggested that runner blade cavitation could cause instability. To clarify this, variation of turbine intake flow was sup-pressed, and the influence of pressure variation via runner blade cavitation on the relative runner exit flow angle and angular-momentum flux was simulated. Due to the upstream boundary condition, the influence of mass-flow gain χ is replaced by a cavitation gain factor ψ, likewise delayed by the limited speed of swirl propagation. It is found that gain factors obtained from steady-state simulation cannot be directly used with a lumped-parameter model because the swirl effect is much reduced due to its phase changes along the vortex; using the steady-state gain factors would thus exaggerate the influence of swirl on cavity volume. Simulation in frequency domain with realistic swirl transport delay confirms that instability can occur because in some parts of the cavitation zone the swirl provides oscillation power.

Experimental and Numerical Heat Transfer Study of Swirling Air Jet Impingement

Experimental and numerical study has been performed to study effect of swirl on heat transfer. A twisted swirl tape with twist ratio (T. R)=2 is used to generate swirl and effect of parameters like z/d=2 to 8 and Re varying between 3000 to 9000 are studied experimentally. Experiments show heat transfer dependency on Reynolds number. This study is further extended numerically using commercial CFD code ANSYS Fluent for much higher Reynolds number flow up to 20000. It is seen that CFD centerline peak Nu profile matches pretty well with experiments conducted. A relation between peak Nu and Re is established numerically for the conditions mentioned above. Further, effect of multiple swirl jet impingement (two jets separated by distance 1.5D, 2D and 3D) on Peak Nu is explained through CFD studies. CFD results show that jet distance of 1.5D is more effective in achieving higher heat transfer compared to 2D and 3D distances.

Flame structure and NOx emission characteristics in a single hydrogen combustor

In this study, the effects of fuel-induced swirl number on the flame structure and NOx emissions are observed. A tube-type nozzle with four fuel injection holes is used. The fuel injection holes are located away from the centerline of the nozzle to induce a low swirl effect in the flow. First, the flame structure changes with the fuel-induced swirl number, separating into four small flames in the high-swirl region; the flames are classified into three types. Subsequently, NOx emissions decrease with an increase in the fuel-induced swirl number. However, this shows a stepwise discontinuous change rather than a gradual change. The NOx emission is linearly proportional to the residence time of the combustion gas, which is calculated using the flame volume and flame structure. In conclusion, the change in the flame structure by the fuel-induced swirl is a decisive factor in the reduction of the NOx.

CFD Simulation Using ANSYS FLUENT of Jet Nozzle of Ethanol at Temperature of 360 K

Spray coating technology is an advanced manufacturing process to break the liquid down into small droplets and disperse these droplets uniformly on the target substrate. The nozzle used in this fabrication process rapidly disintegrates the liquid jet at a direction of motion governed mainly by the prevailing airflow pattern in the spray region environment. According to Navier–Stokes energy equation, the fluid and environmental temperature capable of supplying additional energy to the droplet imparted the ejected liquid jet from the nozzles. With a view to understanding the liquid droplet behaviour at elevated temperatures, this study investigates the jet velocity, pressure, and temperature of ethanol at its evaporation temperature of 360 K using commercial CFD software (ANSYS FLUENT 2020). A numerical simulation of a simple nozzle system with a cone angle of 56° and an outlet radius of 0.1966 mm was modelled at 1 bar inlet pressure to study the effect of the environment temperature on the liquid jet. The result from the temperature profile showed that the liquid jet exhibited turbulence or a swirling effect at elevated temperature as the liquid absorbed thermal energy. The liquid jet temperature increased to the maximum temperature of +3K at a liquid jet distance of 10 cm when compared with normal environment temperature. This numerical study showed that environmental conditions such as temperature can impact the liquid jet quality and properties, which are difficult to observe during experimental work. It is expected that the finding from this work would benefit the industries, leading to better spray nozzle design for future coating applications.

The effect of decay on churn flow transition in a vertical gas–liquid swirling flow

Gas–liquid two-phase swirl flow has been widely used in industry, especially the decayed swirl flow. However, axial development of the decayed swirl flow which is closely related to the effective length of swirl are lack of understanding. In this work, effects of decay on churn flow transition induced by a vane-typed swirler were investigated by a visualization experiment in a long vertical pipe (inner diameter of 62 mm and total length of 11 m). The results show that under the effect of swirl, churn flow can transform to a swirling annular flow, meanwhile the pressure drop increases and its fluctuation weakens compared with these in the non-swirl churn flow. However, the length of the transformed swirling annular flow is limited, due to the decay of swirl intensity. Then the effect of swirl decay on churn flow transition has been analyzed by the theoretical model proposed by our previous work (Liu et al., 2019). Finally, a new method was proposed here to predict the effective length of swirling annular flow transformed from churn flow in the vertical pipe, by combining the swirl decayed model and churn flow transition model in the swirl flow.

Experimental and Numerical Investigation of Recirculation Structures in Isothermal Swirling Coaxial Jet

Abstract Three-dimensional (3D) unsteady Reynolds-averaged Navier–Stokes (URANS) simulations are conducted in a coaxial swirling jet. Two distinct types of recirculation zones (RZ) relevant to coaxial swirling jets are considered based on the modified Rossby number Rom, which is known to represent the ratio of axial velocity deficit between two coaxial streams to the characteristic tangential velocity at the nozzle exit. The two flow states studied are Rom>1 and Rom≤1. The former is characterized by regions of high strain (especially in the shear layer between central and coaxial jet). It is found in this study that renormalization group (RNG) k−ɛ model is the suitable model for 3D URANS simulation of Rom>1 flow state. This is attributed to the model's ability to simulate flow regions that are heavily strained. The simulated results are compared with two-dimensional laser Doppler velocimetry measurements conducted as part of this study. For the flow states Rom≤1, which are characterized by the dominance of radial pressure gradient arising due to rotational (swirling) effect over the pressure gradient due to axial velocity deficit, the Reynolds stress model (RSM) is found best to simulate the flow topologies and mean and turbulent quantities. The time-averaged results obtained from optimized turbulent models are employed to gain insights into the fluid mixing phenomenon in these RZs. The unsteady axial velocity fluctuations obtained from both experiments and URANS simulations are analyzed in the frequency domain to gain insights into dominant axial oscillations prevalent in RZs.

Experimental investigations of indirect noise due to modulation of axial vorticity and entropy upstream of a choked nozzle

An experimental cold-gas study of the response of a choked convergent–divergent nozzle to swirl perturbations is presented. The perturbations were obtained by means of upstream unsteady tangential injections into initially steady flows with different values of steady background swirl. The swirl perturbations induced changes in the axial mass-flow rate, due to either their ingestion or evacuation by the nozzle. This in turn caused a downstream acoustic response. For low-intensity background swirl the responses were found to be similar to those obtained without steady background swirl. Perturbations of a high-intensity background swirl led to different effects. For long injection times, the negative mass-flow rate modulation occurred in two stages. The first stage was similar to that of the background-swirl free case. The second stage occurred after a short time delay, and induced a much stronger negative acoustic response. This unexpected behavior suggests that a significant part of the tangentially injected fluid flows upstream inducing an accumulation of swirl, which is – after tangential injection is ceased – suddenly cleared out through the nozzle. A scaling rule for the amplitudes of these acoustic responses is reported. Furthermore, quasi-steady models, based on steady-state measurements are proposed. These models predict the downstream acoustic response amplitude within a factor two. Additionally, preliminary empirical evidence of the effect of swirl on the downstream acoustic response due to the interaction of entropy patches with a choked nozzle is reported. This was obtained by comparison of sound produced by abrupt radial or tangential sonic injection, upstream from the choked nozzle, of air from a reservoir at room temperature to that from a reservoir with a higher stagnation temperature. Because the mass flow through the nozzle does not increase instantaneously, the injected higher-enthalpy air accumulates upstream of the injection-port position in the main flow. This eventually induces a large downstream acoustic pulse when tangential injection is interrupted. The magnitude of the resulting sound pulse can reach that of a quasi-steady response of the nozzle to a large air patch with a uniform stagnation temperature equal to that of the upstream-injected heated air. This hypothesis is consistent with the fact that the initial indirect-sound pulse is identical to one obtained with unheated air injection. The authors posit that – given all of the insight gleaned from them in this case – acoustic measurements of indirect sound appear to be a potentially useful diagnostic tool.

Effect of Swirl on Temperature Decay Function in Straight Blade Liquid Fuel Swirl Burner

The need to shield the surroundings from fire or combustion generated pollutants has led to substantial demand for perk up burner design with better performance. In this study, the geometry of a liquid fuel burner has been modified by introduction of straight edge blade swirler and thereafter, measurement using chromium-zinc thermocouple of radial and axial temperature distributions. The straight blade swirl generator consists of 6 number of blades at angles 20°, 30°, 40°, 50° and 60°, respectively was fired by conventional diesel in an experimental model liquid fuel swirl burner. The highest axial temperature of combustion without and with swirler was 930℃ and 1121℃, respectively, while the highest radial temperature without and with swirler was 942℃ and 1130℃, respectively. The achieved 21% performance improvement suggests that burners with swirl have varied higher flame temperature and combustion intensity than their counterpart without swirl. The outcome of this study has revealed that higher agitation of the swirl significantly affected the thermal profile and this subsequently led to high combustion intensity. The changes can be attributed to turbulence being provoked at selected angles of swirl blade. The effect is enhanced as the angle of swirl blade increases, howbeit, until a threshold is reached.

Effect of nanofluids on heat transfer characteristics of an aerodynamic swirl nozzle for isothermal and isoflux conditions

ABSTRACT Achieving axisymmetric boundary conditions in turbulent swirl flows and predicting thermo-fluidic behaviours within a nozzle is often a challenge due to the difficulties of measurement diagnostics. Adding nanoparticles to ase fluids exacerbates the complexity because of the regeneration of effective properties of the fluid medium. As such, this study numerically investigates the flow and thermal characteristics for the effect of swirl and nanofluids of incompressible turbulent liquid jets. The results show that the axial and tangential velocity profiles for water-based nanofluids resemble to those for water in no-to-high swirl flows. The surface Nusselt number for strong swirl flow reduces with axial distances at isothermal wall condition, and the Nusselt number is strongly dependent on types of nanofluid for isoflux condition. Water-based nanofluids cause higher heat transfer compared to Dowtherm+Al2O3 and Syltherm800+ Al2O3. The average Nusselt number and the pressure drop are found to be the largest for 10% volume fraction. The increase of thermal-hydraulic performance factor for nanofluids after nozzle convergence is steeper for highly swirling flow than for non-swirling and medium swirling cases. A strong turbulent kinetic energy is observed immediately after the nozzle converging section for all nanofluid cases and Dowtherm+Al2O3 shows relatively uniform distributions across the nozzle.

Investigation of plasma swirl dynamics and effects of secondary gas injection in a vortex gas stabilized DC arc plasma

A numerical analysis of plasma gas swirl is performed to gain an understanding of fluid motion and the contact pattern of the plasma with a secondary gas. The secondary gas is injected into the plasma torch to either quench the hot plasma or alternatively to facilitate the heating of this secondary gas. A three-dimensional, transient fluid model is implemented in the OpenFOAM solver to examine the arc and plasma dynamics. The gases (plasma gas as well as secondary quench gases) are injected via 2 sets of 4 tangential ports spaced apart at a specified distance. The tangential injection create a plasma gas vortex that facilitates the swirling of the arc inside the torch. The plasma swirl propagates in the downstream direction where it mixes with the quench gas. The simulation results reveal that the operating arc current has a significant impact on the decay of plasma gas swirl in the downstream direction. At high arc currents, the rise in the joule heating enhances the cathode jet which suppresses the velocity gradients of the incoming swirl. A high inlet gas flow rates (e.g. Q = 18 slpm) have been observed to retain the inlet swirl intensity after passing through the arc column compared to the case with low gas flow rate (e.g. Q = 4.5 slpm). We have also examined the impact of secondary gas swirl on the quenching behaviour plasma torch plume by feeding the secondary gas in a co-current and counter-current with respect to the plasma gas rotational direction. The present simulation results help in understanding the effect of key process parameters controlling the flow and mixing behaviours in vortex stabilized plasma torch.

SOLVING A TWO DIMENSIONAL ENVIRONMENT WITH REINFORCEMENT LEARNING

Petroleum fuel prices are often rising due to the rapid depletion of natural resources, which are exorbitantly expensive for the average consumer, especially in the situation in India. Therefore, C.I. The importance of alternative fuel engines for use in is increasing. Much research has been done on alternative fuels. Intensive research is being conducted in the area of improving the thermal efficiency of engines. This shows that in a naturally aspirated diesel engine, only one-third of the heat supplied is converted to work. Many methods are recommended by some experts and researchers to improve engine performance characteristics. The purpose of this study is to increase the swirl effect in the cylinder, improve performance and reduce emissions. In DI diesel engines, swirls can increase the mixing speed of fuel and air. The vortex interaction with the squish flow caused by compression increases the level of turbulence in the combustion bowl and promotes mixing. It is clear that the effect of the shape has very little effect on the airflow during the inspiratory stroke and in the early part of the compression stroke. However, as the piston moves towards top dead center (TDC), the shape of the bowl has a significant effect on airflow, improving atomization, mixing and combustion. In CI, the engine piston shape of the head is a flat and concave combustion chamber, and the engine was driven in this shape. However, it is not possible to mix the air-fuel ratio mixture properly here. To avoid this, shape of the piston was changed. Keywords: D.I. Diesel Engine, Bio- Diesel, Apricot oil, Beak Grooved Piston, B10, B20 and B30.

Evaluation and Improvement of the Performance of a Wellhead Multistage Bundle Gas–Liquid Separator

A wellhead multistage bundle gas–liquid separator combining a gas–liquid cylindrical cyclone (GLCC) with multi-tube bundle components is expected to improve the gas–liquid separation performance. However, there is no unified understanding of the factors influencing the separation performance of the separator. The continuous improvement and applications of the separator are restricted. This paper evaluated the performance of the separator using a numerical simulation method. The results indicate that the separation flow field evolves to be uniform with the increased water cut when the gas–oil ratio and flow rate remain constant. Compared with a 30% water cut, the separation efficiency at a 50% water cut increased by 5.88%. When the gas–oil ratio and water cut remained constant, the swirl effect of the primary separation was enhanced. The separation efficiency increased to more than 70% when the flow rate was 15 m/s. When the flow rate and water cut remained unchanged, the pressure of the separation flow field was reduced. However, when the gas–oil ratio was greater than 160 m3/t, the flow field trace density of the secondary separation bundle was reduced, and the separation efficiency was also lower than 60%. The separation efficiency can be further improved by optimizing the number and diameter of secondary separation bundles.

Numerical study of the effect of Inlet paired Swirl on Performance and Stability of Axial compressor

In order to study the effect of inlet paired swirl distortion on the performance and stability of compressor, a full-annulus unsteady numerical simulation of the effects of swirl distortion on performance and stability of transonic rotor Rotor 37 is carried out in this paper. The result shows that: the rotor performance deteriorates and the stable working range decreases under the effect of vortex flow distortion; the circumferential side flow caused by vortex swirl distortion leads to the uneven circumferential distribution of flow parameters at the inlet and the outlet of the compressor; the rotor blade has a very significant attenuation effect on the swirl distortion, and the swirl distortion intensity decreases along the axial direction; the circumferentially inhomogeneous distribution of rotor angle causes excessive local aerodynamic load on the rotor, and high intensity leakage vortices and excitation vortices are generated at the blade tip. The circumferentially unevenly distributed swirl angle causes excessive local aerodynamic load of the rotor, resulting in high-intensity leakage vortex and shock wave interference in the blade tip area, which severely blocks the flow path and eventually leads to unstable flow in the Rotor37.

Influence of piston crown shape with different positions of spark plug and fuel injector, %EGR, and fuel system control on emissions from modified GDI engines compared with a base diesel engine

In this study, the combustion chamber profiles were developed for spray, wall, and air-guided gasoline direct injection (GDI) engines. For each combustion chamber geometry of GDI engine, the piston crown surface was modified, from hemispherical bowl, to trapezoidal bowl, and a pent roof shape that included a scoop type bowl on one side (towards injector position) to impart better squish, swirl, tumble, and turbulence effects to improve the mixing characteristics. Also, the cylinder heads were modified for each combustion chamber geometry by changing the locations of the spark plug and fuel injector. Further, the fuel split injection timings with duration, ignition timing, and the percentage of exhaust gas recirculation were optimized to reduce an engine out emissions; especially soot and nitrogen oxides. Emission tests were conducted on the base diesel engine and the GDI engine with the three different combustion chamber geometries. It is clear from the results that the emission of nitrogen oxides in the wall-guided mode was reduced by 5% till 75% of the load when compared with spray-guided and air-guided combustion modes. Overall, the GDI engine with the wall-guided combustion chamber geometry produced better results at 150 bar fuel injection pressure when compared with the base diesel engine; nitrogen oxides emission was reduced from 377 to 77 ppm and soot emissions were reduced from 29.3 to 4.5 g/km at high torque.

Experimental investigation of heat transfer characteristics of an inverse diffusion flame in a coaxial tube burner for with and without swirl

Heat transfer by flame jet impingement is widely used in many of the industrial and domestic applications like heating metal bars, scrap melting, shaping the glass, metal slab cutting, domestic cooking and others. Aim of the present experimental work is to study an effect of swirl on a local heat flux distribution of an inverse diffusion flame (IDF) jet impinging on a flat target surface in a coaxial tube burner. The twisted tape of twist ratio 3 (corresponding to the swirl number, S = 0.52) is used to create a swirl in the central air jet of the burner. The flame shapes and heat flux distributions are compared for the with and without swirling IDF under the different air jet Reynolds number (Rea) of 1000 to 2500, equivalence ratio (ϕ) of 0.4 to 1.3 and a burner-to-impingement plate distance (H) of 10 to 100mm. The distributions of heat fluxes are studied within a radius of 75 mm from the point of stagnation on an impingement plate. Results show that the swirling IDF helps in clean combustion of the fuel with much shorter flame height. Swirling in the flame jet enhances the peak heat flux for the higher air jet Reynolds number for slightly fuel rich conditions of ϕ = 1.1 at the optimal burner-to-target plate distance of 40 mm.

Can hysteroscopy be substituted to hysterosalpingography in the assessment of infertility? Methods of showing tubal transition as hysteroscopic

Background: The main goal of this study was to prove that hysteroscopy is a superior method compared to hysterosalpingography in the evaluation of tubal passage and the uterine cavity in infertile women. Methods: The study was carried out on 30 volunteer women for whom evaluation of the uterine cavity and transit through the tubules was required due to infertility. In the evaluation of the hysteroscopic tubal passage, a 6Fr feeding cannula was advanced from the hysteroscope barrel, and firstly methylene blue and then an air bubble were applied to the fluid-filled uterine cavity through this flexible cannula. Results: When the reference method was taken as hysterosalpingography, the specificity of hysteroscopy was found to be 85.71% (95% CI (confidence interval): 42.13%–99.64%), sensitivity 94.74% (95% CI: 85.38–98.90%). The positive predictive value of hysteroscopy was calculated as 98.18% (95% CI: 89.78%–99.70%) and the negative predictive value was 66.67% (95% CI: 38.96%–86.24%). Observing the bubble and swirl effect together in the evaluation of the tube opening increases the diagnostic accuracy. And benefit of hysteroscopy in the evaluation of tubal passage was statistically significantly higher than hysterosalpingography. Conclusion: Considering the cellular damages that can be caused by hysterosalpingraphy and the real observation power provided by hysteroscopy, simultaneous evaluation and the comfort of making intervention possible, hysteroscopy will be a more useful and useful application.