Supersonic Steam Research Articles

New Design Method of a Supersonic Steam Injection Nozzle and Its Numerical Simulation Verification.

Steam huff-n-puff in horizontal wells often had limitations, such as uneven steam injection and low reservoir utilization. To improve steam injection efficiency, a new method for designing a supersonic nozzle was proposed based on the principles of aerodynamics and thermodynamics. The nozzle featured a tapering section, a throat, and a diverging section. The best geometric shape of the tapering section was the Witoszynski curve. A set of nozzle size designs were established, and the size parameters were optimized. The results showed that the nozzle could inject steam into the formation at supersonic speed and it had the characteristics of constant flow rate and uniform development of the steam chamber. According to the steam Reynolds number and the good aggregation distribution characteristics of the size design model, three sequential nozzles of 3.0, 5.0, and 6.5 mm were formed based on the throat. When the throat diameter was 5.0 mm, the tapering length was 4.3 mm, the diverging length was 5.5 mm, the throat length was 3.0 mm, the inlet diameter was 9.8 mm, and the outlet diameter was 6.2 mm. Numerical simulations indicated that the pressure drop loss during steam huff-n-puff injection in horizontal wells was within 10%. It was of great significance to establish the nozzle size design model of the steam injection effect of horizontal wells.

An experimental study of steam turbulent jet condensation & upward propagation of thermal plume into sub-cooled water pool

Supersonic steam’s axial injection into water in a cylindrical vessel (1 m high and 24 cm in diameter) was achieved through a nozzle of 6 mm diameter, located at the center of the vessel. Optical examinations were determined through a steam jet to find out condensation rate, which was allied with the steam mass flux (295–672 kg/m2/s) while leaving the nozzle’s exit. The Reynolds number (i.e., 41,000–73,610) has been estimated based on most swollen section of the steam’s jet. Further beyond the condensation zone, the steam, that has been condensed, progresses into a condensed steam plume, which is surrounded by the sub-cooled water. Particle Image Velocimetry (PIV) has been applied to focus region through the mid axis of the heated water plume along a vertical plane of 100 mm × 100 mm cross sections till 400 mm from the nozzle. Central upward averaged velocity profile of the condensed water thermal plume has been evaluated at 295 and 672 kg/m2s, both have hinted the exponential decrease of mean axial velocity when the plume travels vertically upward. The radial velocity distribution of the mean axial velocity across the radial dispersal of the jet, has been obtained as self-preservable and the mean axial velocity attained the Gaussian profile by incorporating appropriate grading of axial distance and mean velocity. Other significant aspect of the current work is to apply the buoyant scaling evolved from the single-phase non-condensing upward thermal plumes to the condensed upward plume through the relations of volume flow, momentum and buoyant being computed from the steam jet operating conditions. The source values of physical dimensionless parameters such as Reynolds number (Reo), Plume Richardson number (Ripo), entrainment coefficient (αo), buoyant vertical scale (Bo) have been evaluated. Based on the radial spread of the velocity profiles along the vertical distance from the condensation region, the dynamics of the thermal and the jet propagation has been highlighted through the evaluation of the dimensionless buoyant parameters along the downstream of the plume. The present experimental measurements obtained for condensed single-phase plume are compared with the experimental results of the non-condensed single-phase thermal plume to signify the vitality of the dimensionless parameters derived from non-condensed plumes.

Hydrodynamics of Supersonic Steam Jets Injected into Cross-Flowing Water

High-speed gas/vapour jets injected into a cross-moving sonic liquid signifies a vital phenomenon which bears useful applications in environmental and energy processes. In the present experimental study, a pulsating jet of supersonic steam was injected into cross-flowing water. Circulation zones of opposite vorticity owing to the interaction between the steam jet and cross-water flow were found. However, a large circulation appeared in front of the nozzle exit. Also, most small circulation regions were observed at higher water-flow rates (>2 m3/s). Among the prime mixing variables (i.e., turbulence kinetic energy (TKE) and Reynolds shear stress (RSS)), the RSS estimations backed a small diffusive phenomenon within a region far from the nozzle exit. Further information extracted from the PIV images indicated the existence of Kelvin–Helmholtz (KH) instabilities. The counter-rotating vortex pairs (CVPs) appeared to be significant in the region close to the nozzle exit, and they exhibited leeward side folds. Moreover, the effects of the operating conditions on the pressure recovery and mixing efficiency as well as the penetration and the separation height were evaluated to determine the optimisation of the phenomenon. By applying extreme difference analysis, the mixing efficiency was found as the most influential parameter.

Performance and mixing process investigation of a novel mixing-enhanced ejector

Ejector refrigeration systems rarely require electrical energy, satisfying the requirements of sustainable development and low carbon emissions. However, owing to the limitations of the operating conditions, the ejector performance is not sufficient, and there is an urgent need to improve the entrainment performance of the ejector. In this study, experiments and numerical simulations were performed on a conventional ejector, and the numerical simulation results were fitted with the experimental data. A numerical simulation was used to investigate the mixing process and entrainment performance of the novel mixing-enhanced supersonic steam ejector. The optimal values of lm = 120 mm and dc = 57.5 mm achieved the best entrainment ratio (0.778) for the novel ejector under 5%-tab blockage ratio. The results showed that the entrainment performance of the novel ejector improved by 51.1–54.7% and 10.5–12.3% compared to those of the conventional ejector and the conventional ejector with an adjusted mixing chamber, respectively. This was because the generated streamwise vortices entrained more secondary flow into the mixing chamber, and the mixing process between the primary and secondary flow avoided unnecessary kinetic energy loss, increasing the mixing efficiency and accelerating the secondary flow crashing out of the diffuser.

Investigation on High-Viscosity Chemical Waste Liquid Atomizer Based on VOF-DPM

The viscosity of adiponitrile waste liquid is as high as 1000 cp. It is challenging to spray and atomize the waste liquid normally. Based on the coaxial three-channel pneumatic atomizer, a two-stage supersonic steam atomizer is proposed in this paper, and the atomization process is simulated by Fluent software. Compared with the traditional atomization simulation method, the Volume-of-Fluid to Discrete-Phase-Model (VOF-DPM) bi-directional coupling model and Adaptive Mesh Refinement (AMR) technology can save mesh and improve the computational efficiency. The atomization processes of primary breakup and secondary breakup are entirely captured and analyzed. The results show that the Sauter Mean Diameter (SMD) is about 116–180 μm, the SMD decreases with the increase of steam inlet absolute pressure, and the atomization quality can meet the combustion requirements. This study can be used for the performance optimization of the high-viscosity liquid atomizers in the chemical and aerospace industry and shorten the time engineers spend in the simulation calculation to verify the rationality of the structure.

The effect of variable motive pressures on the performance and shock waves in a supersonic steam ejector with non-equilibrium condensing

Complex flow phenomena and performance are not fully understood in supersonic steam ejectors as the neglect of the non-equilibrium condensation in many simulation studies. In this paper, a non-equilibrium condensation model including real physical properties was combined with the SST k-ω turbulence model to investigate the effects of variable motive pressures on the shock waves, non-equilibrium condensation, and ejector performance. The essential connection between the performance and shock waves was revealed from the mechanism perspective. The results show that when the shock wave intensity is the lowest and the shock wave number is the least whereas the second choking forms, the motive pressure is optimal. The closer the shock wave is to the second choking starting position near the diffuser entrance, the closer the discharge pressure is to the critical one. When the motive pressure increases, a dramatic increase in velocity dominates the increase in the mass flow rate of suction steam in the single choking mode; the over-expanded primary shock train region significantly squeezes the suction steam flow region and dominates the decrease in the mass flow rate of suction steam in the double choking mode; the intensity of the non-equilibrium condensing and shock waves increases, the pseudo-shock region expands, and the condensation shock wave position moves upstream by 1.2% while aerodynamic shock waves move downstream by 25.9%.

Influence of Geometrical Parameters on Supersonic Steam-Ejector Performance

Geometrical parameters such as the nozzle exit position (NXP) and the diameter ratio (DR) considerably influence the performance of steam ejectors. An axisymmetric two-dimensional model for a supersonic steam ejector is developed to investigate the steam-ejector performance with the aim of simultaneously optimizing the NXP (-10 < NXP < 10) and DR (6 < DR < 10), and the simulation results are in good agreement (relative error was merely 7%) with the experimental results. At the optimum value of the NXP, the supersonic steam ejector acquires the optimal entrainment ratio (ER) under the given conditions. Deviation from the optimal NXP value may result in a 12.4% decrease in ER. With optimized NXP, the optimization of DR is more significant; however, a deviation from the optimal DR weakens the ER and the supersonic steam ejector eventually breaks down. Therefore, the NXP should be approximately close to its optimum value, and the DR must be designed at its optimum value to ensure effective operation of the supersonic steam ejector.

Turbulence Model Comparative Study for Complex Phenomena in Supersonic Steam Ejectors with Double Choking Mode.

Scholars usually ignore the non-equilibrium condensing effects in turbulence-model comparative studies on supersonic steam ejectors. In this study, a non-equilibrium condensation model considering real physical properties was coupled respectively with seven turbulence models. They are the k-ε Standard, k-ε RNG, k-ε Realizable, k-ω Standard, k-ω SST, Transition SST, and Linear Reynolds Stress Model. Simulation results were compared with the experiment results globally and locally. The complex flow phenomena in the steam ejector captured by different models, including shock waves, choking, non-equilibrium condensation, boundary layer separation, and vortices were discussed. The reasons for the differences in simulation results were explained and compared. The relationship between ejector performance and local flow phenomena was illustrated. The novelty lies in the conclusions that consider the non-equilibrium condensing effects. Results show that the number and type of shock waves predicted by different turbulence models are different. Non-equilibrium condensation and boundary layer separation regions obtained by various turbulence models are different. Comparing the ejector performance and the complex flow phenomena with the experimental results, the k-ω SST model is proposed to simulate supersonic steam ejectors.

Measurement of turbulent supersonic steam jet flow characteristics using TDLAS

Ejectors have no moving parts and are preferable to mechanical compressors in many applications, but ejectors typically have a relatively low efficiency. To aid in the ejector design process, thorough understanding of the turbulent mixing of multi-phase compressible jets is beneficial.This paper reports experimental results for Tunable Diode Laser Absorption Spectroscopy (TDLAS) measurements derived from an axisymmetric supersonic steam jet apparatus.In this experimental work, a supersonic steam jet nozzle exit of a diameter 13.6 mm was surrounded by a low-speed flow of dry nitrogen. The TDLAS system was traversed through the flow at three different planes downstream from the ejector nozzle exit: 15, 20, and 30 mm distance. At each of the three planes, line-of-sight measurements were made with the laser passing through locations between 0 and 15 mm from the jet centreline.Through the analysis of the TDLAS data and application of the Abel inversion method, the radial distribution of the pressure, temperature, and the concentration of the water-vapour were obtained. The key findings are that it is possible to determine key physical parameters using experimental TDLAS measurements when combined with a suitable numerical optimization approach.

High Temperature Fracture Resistance of Model Kraft Recovery Boiler Deposits

In kraft paper mills, supersonic steam jets are used to remove deposits that build up on the heat exchanger tubes in the recovery boiler. In this study, the fracture toughness KC and work of fracture, WF, of simulated boiler deposits were measured at temperatures up to 500 °C to determine the optimal conditions for deposit removal. The model deposits experienced an important brittle to ductile transition at ~450 °C. Above this temperature, ductile deposits required lower peak force, but four times more energy to fracture when compared to those tested at lower temperatures. The transition was clear in scanning electron micrographs of the fracture surfaces. The findings have significant implications for mills wishing to optimize sootblower performance.

Double choking characteristics of three-dimensional steam ejector with non-equilibrium condensing

The phenomenology of double choking in a supersonic steam ejector which plays an influential role in the performance is not fully understood because the non-equilibrium condensing and three-dimensional effects are neglected in most numerical simulations. In this paper, a non-equilibrium condensation model was combined with the k-ω SST turbulence model to simulate three-dimensional supersonic steam ejectors with different working conditions and different structures. The internal relationship between the ejector performance and the double choking characteristics was revealed. The influence of the characteristics of double choking on the shock waves in the ejector was also investigated. Results show that when the minimum distance between the sonic velocity line in the diffuser and the wall is equal to the critical minimum distance which is 0.21 mm, the steam ejector is in a double choking mode. 4 mm downstream of the diffuser entrance is the critical second choking position. The deviations between discharge pressure and critical discharge pressure are getting greater with the increase of the second choking length. The intensity and number of shock waves in the diffuser are positively related to the second choking length with certain working conditions. Three-dimensional effects bring non-negligible differences to both the flow field and the ejector performance.

Experimental study on steam plume shape characteristics for bevelled spray nozzles exhausting into quiescent water

Steam-water direct contact condensation phenomenon is being widely used in many industries including chemical, thermal and especially in nuclear industry due to its efficient heat and mass exchange capabilities. The present experimental study explores the underlying physics of the steam cavity/plume shapes by condensing supersonic steam exhausting from five different bevelled nozzles into quiescent water tank. Based on the high speed image capturing methodology, the effects of steam pressure, water temperature and nozzle exit inclination angle on the cavity shape characteristics have been studied. Existence of six different plume shapes (oscillatory, conical, expansion–contraction, double expansion contraction, cylindrical and divergent) have been identified. The results show that for a fixed nozzle geometry, with the increase in water temperature and steam pressure, the steam jet becomes lengthy. However, under the same steam pressure and water temperature conditions, the plume shortens with the increase in nozzle exit inclination angle. The dimensionless jet length has been found in the range of 1.26–5.64. Furthermore, it has been observed that steam plume exhausting from bevelled nozzle undergoes deflection from its nozzle symmetry axis possibly due to the pressure difference between upper and lower lip of nozzle. This deflection may either be upward oriented at high steam pressure or downward deflected at lower steam pressure. Additionally, on the basis of findings from 175 No’s of experiments, condensation regime maps have also been developed for bevelled spray nozzle.

The Effect of Different Pressure Conditions on Shock Waves in a Supersonic Steam Ejector

The complex flow phenomena in a three-dimensional supersonic steam ejector were simulated with a non-equilibrium condensation model including real physical properties in different pressure conditions. The different working conditions include discharge pressure, motive pressure, and suction pressure. The influence of different pressures on shock waves in the steam ejector was investigated comprehensively. The intrinsic causes of shock wave variation with pressure conditions were explained in detail. The results show that the width of the primary shock train region expand with an increase in the motive pressure or a decrease in suction pressure. The diamond shock waves move downstream with an increase in motive pressure or a decrease in suction pressure. The shocking position in the diffuser moves upstream until it reaches the diffuser entrance with an increase in discharge pressure or a decrease in motive pressure or suction pressure. The intensity and number of oblique shock waves in the diffuser increase with an increase in motive pressure and suction pressure or a decrease in discharge pressure. The existence of only one shock wave in the diffuser is a necessary and insufficient condition for the ejector to enter a double choking mode.

Dynamics of chugging phenomenon induced by subsonic and supersonic steam–air jet condensation in water flow

Chugging, a typical unstable flow pattern caused by steam-water direct contact condensation, should be paid more attention in engineering applications due to its accompanying low-frequency and high amplitude pressure pulse. In this paper, it was experimentally found that both subsonic and supersonic steam–air jet condensation could trigger chugging in a confined channel. As for such conditions, the chugging-caused pressure pulses all had two dominant frequencies with different amplitudes, and the one with larger amplitude was mainly distributed in the low-frequency zone of 15–45 Hz and 30–50 Hz. The brilliant image of steam-water phase interface captured by a high-speed camera showed that the mechanism of chugging was the sharp and low-frequency stretching and shrinking of the phase interface because of the periodic aggregation and dissipation of air layer. The subsonic steam–air jet condensation could trigger chugging only with a small amount of air, which therefore should be prevented as far as possible in engineering. However, for supersonic steam–air jet condensation, chugging could be triggered as soon as the air mass fraction reached a critical value because the incoming flow had severely damage effect on the air layer. By considering the steam mass flux, condensation driven potential, water Reynolds number and air mass fraction, the correlations of dominant frequency of chugging for subsonic and supersonic steam–air jet condensation were given, with deviations in the range of ± 20% and 15%, respectively.

Study of steam jet characteristics and regime maps for bevelled spray nozzles exhausting into quiescent water

Steam-water direct contact condensation phenomenon is being widely used in industrial applications due to its rapid heat and mass transfer rates. The present experimental study explores the underlying physics of the steam jet characteristics by condensing supersonic steam exhausting from five different bevelled nozzles into quiescent water tank. Based on the image processing approach, the effects of steam pressure, water temperature and nozzle exit inclination angle on the size and shape of the steam jet have been studied. The dimensionless steam jet length and maximum expansion ratio have been found in the range of 1.18–5.64 and 1.03–2.70, respectively. The results show that the dimensionless penetration length increases with the increase of steam pressure and water temperature, and decreases with increase in nozzle exit inclination angle. Similarly, maximum expansion ratio of steam jet increases with steam pressure, water temperature and nozzle exit inclination angle. It was observed that steam jet exhausting from bevel nozzle undergoes deflection from its nozzle symmetry axis. The deflected angle increases with steam pressure and nozzle exit inclination angle. A theoretical model of steam jet length for bevelled nozzle has also been presented whose accuracy is found to be within ±30% of the experimental data. Additionally, condensation regime diagrams have been proposed on the basis of steam pressure, water temperature and nozzle exit inclination angle. Existence of seven different plume shapes in regime maps have been identified.

Assessment of Different CFD Modeling and Solving Approaches for a Supersonic Steam Ejector Simulation

The effects of different modeling and solving approaches on the simulation of a steam ejector have been investigated with the computational fluid dynamics (CFD) technique. The four most frequently used and recommended turbulence models (standard k-ε, RNG k-ε, realizable k-ε and SST k-ω), two near-wall treatments (standard wall function and enhanced wall treatment), two solvers (pressure- and density-based solvers) and two spatial discretization schemes ( the second-order upwind scheme and the quadratic upstream interpolation for convective kinematics (QUICK) of the convection term have been tested and compared for a supersonic steam ejector under the same conditions as experimental data. In total, more than 185 cases of 17 different modeling and solving approaches have been carried out in this work. The simulation results from the pressure-based solver (PBS) are slightly closer to the experimental data than those from the density-based solver (DBS) and are thus utilized in the subsequent simulations. When a high-density mesh with y+ &lt; 1 is used, the SST k-ω model can obtain the best predictions of the maximum entrainment ratio (ER) and an adequate prediction of the critical back pressure (CBP), while the realizable k-ε model with the enhanced wall treatment can obtain the best prediction of the CBP and an adequate prediction of the ER. When the standard wall function is used with the three k-ε models, the realizable k-ε model can obtain the best predictions of the maximum ER, and the three k-ε models can gain the same CBP value. For a steam ejector with recirculation inside the diffuser, the realizable k-ε model or the enhanced wall treatment is recommended for adoption in the modeling approach. When the spatial discretization scheme of the convection term changes from a second-order upwind scheme to a QUICK scheme, the effect can be ignored for the maximum ER calculation, while only the CBP value from the standard k-ε model with the standard wall function is reduced by 2.13%. The calculation deviation of the ER between the two schemes increases with the back pressure at the unchoked flow region, especially when the standard k-ε model is adopted. The realizable k-ε model with the two wall treatments and the SST k-ω model is recommended, while the standard k-ε is more sensitive to the near-wall treatment and the spatial discretization scheme and is not recommended for an ejector simulation.

Experimental study of the hydrodynamics of a supersonic steam jet impinged on a wall in vertical and oblique orientations

Experimental study of the hydrodynamics of a supersonic steam jet impinged on a wall in vertical and oblique orientations

Erratum to: Conductivity Sensors Based System Development and Application to Investigate the Interfacial Behaviour between Supersonic Steam Jet and Water

Erratum to: Conductivity Sensors Based System Development and Application to Investigate the Interfacial Behaviour between Supersonic Steam Jet and Water

Flow Characterization Near the Nozzle Exit of the Supersonic Steam Jet Injecting into the Stagnant Water

There has been a large amount of work being conducted on the thermo-dynamics of the Direct Contact Condensation (DCC), however, not much attention was given to the phenomena particularly active near the steam’s nozzle exit. A transparent rectangular upright duct of 4 ft high, was built with a supersonic nozzle positioned at the bottom of the channel to characterize flow behavior near the steam nozzle’s exit. Particle image velocimetry (PIV) was applied to draw information on the steam’s jet penetration into the water as well as the entrainment and mixing between the two phases under the steam’s inlet pressure ranging from 1.5 – 3.0 bars. PIV normalized contour measurements depicted not appreciable changes in the radial velocity of the jet. Whereas, in the core region of the jet, the change in the jet’s velocity was not much till Y/De ~ 4.3 and the vertical velocity of the jet decreased slowly till Y/De ~ 8. The jet’s normalized upward velocity attained an optimized value between Y/De ~ 8 and Y/De ~ 9.8. With varying pressures, 1.5 bars to 3.0 bars, the jet expanded radially in water. It was also found in the near nozzle exit region, the shear layer’s thickness remained within 0.2 – 0.5 De over the 1.5 – 3.0 bars pressure. Probability Density Function (PDF) analysis of Reynolds shear and normal stresses confirmed the existence of the velocity fluctuations across the shear layer, owing to the large eddies across the steam-water interface.

Conductivity Sensors Based System Development and Application to Investigate the Interfacial Behaviour between Supersonic Steam Jet and Water

Conductivity Sensors Based System Development and Application to Investigate the Interfacial Behaviour between Supersonic Steam Jet and Water