Gas In Region Research Articles

Investigation of full-scale porous injector plate transpiration cooling coupled with combustion in high-thrust H2/O2 rocket engines

The high chamber pressure and large heat flux impose greater demands on the structure cooling and thermal protection of the future high-thrust H2/O2 rocket engine. To investigate the applicability of transpiration cooling on the full-scale injector plate in the high-thrust rocket engine, a numerical model is presented, in which the porous region and the mainstream hot gas region are directly coupled. The local equilibrium model and eddy dissipation model are considered. The numerical model is validated by transpiration cooling experiments for a subscale rocket engine injector plate. Then, the numerical simulation of transpiration cooling for the high-thrust H2/O2 rocket engine injector plate shows that the transpiration cooling with 13% of the total hydrogen mass flow rate can reduce the gas side temperature of the injector plate by about 150 K and reduce the thermal penetration depth to 9.2% of the plate thickness. Moreover, As the coolant mass flow rate increase from 4% to 13%, the gas side temperature of the plate decreases from 735 K to 668 K and the cooling effectiveness rises. The lower the coolant inlet temperature, the lower the plate temperature, but the higher the cooling effectiveness. Besides, the plate temperature drops with the decreases of the thermal conductivity of the porous media.

Gas Injection and Suction Effect on the Instability of a Supersonic Boundary Layer

We present the results of an investigation of the boundary layer stability on a flat plate having a region of gas injection/suction normal to the wall at a large supersonic freestream Mach number. The laminar flow past a flat plate having a region of distributed injection/suction of fixed intensity is modeled numerically using the integration of Navier—Stokes equations. The unstable disturbances in the boundary layer distorted by injection/suction are analyzed within the framework of the linear stability theory and the eN{{e}^{N}} method for compressible flows. High-frequency disturbances belonging to the plane second mode of the boundary layer, which are the most unstable at high velocities, are considered. It is shown that gas injection/suction leads to a nonmonotonic variation of disturbance growth rates with the appearance of stabilization/destabilization regions, as compared with the case in which injection/suction is absent.

Geological Structure of Deep-Submerged Complexes of Sedimentary Basins: Hydrogeological Anomalies and Oil and Gas Potential as a Result of Implementation of Deep-Seated Fluids (on Example of the South Mangyshlak Fields)

The authors of the article substantiate the induced nature of hydrogeological anomalies in deep-submrged complexes of sedimentary basins. As a result of significant catagenetic transformations, the rocks of the lower hydrogeological floor have practically lost their primary capacitance-filtration properties. The water saturation of the rock matrix, the focal nature of the development of secondary reservoirs against the background of extremely low permeability of the surrounding strata makes it impossible to develop elision flows. This causes the high sensitivity of the lower floor to various compression processes, including those caused by the intrusion of the deep high-energy fluid flows. The injection of these fluid flows into low-permeability strata leads to the formation of centers of desalinated waters of various hydrochemical types, from hydrocarbonate-sodium to calcium chloride, and also to the formation of hydrodynamic anomalies. When moving away from the intrusion channels, the hydrodynamic and hydrochemical parameters gradually level off, approaching the background value. It is shown that when fluids are difficult to move upward, hydraulic fracturing occurs in the layers into which the oil-water mixture enters under high pressure. The injection of fluids into the formation is accompanied by the decompression of low-permeability strata, the formation of additional fractures, and the formation of secondary voids of metasomatic origin. As a result, secondary reservoirs of complex morphology are formed, filled with hydrocarbons. The coincidence in terms of hydrogeochemical and hydrodynamic anomalies, areas of secondary reservoirs with distinct traces of metasomatosis and associated accumulations of oil and gas indicate their genetic relationship. The oil and gas reservoirs and their accompanying hydrogeological anomalies are considered on the example of the fields of the South-Mangyshlak oil and gas region, which is part of the North Caucasian-Mangyshlak oil and gas province.

DETONATION OF A COMBUSTIBLE GAS MIXTURE UPON THE INTERACTION OF A SHOCK WITH AN ELLIPSOIDAL INERT GAS BUBBLE

Interaction of a shock wave in a combustible gas mixture with an ellipsoidal region of an inert gas of increased density is numerically simulated using the Euler equations in two-dimensional plane and axisymmetric formulations. Four qualitatively different regimes of indirect initiation of detonation have been found: upon reflection of a wave from the gas interface, upon focusing of secondary transverse shock waves on the axis/plane of symmetry, upon amplification of a transverse wave converging to the axis of symmetry, and upon secondary focusing of waves in front of the bubble. It is shown that the mode of detonation initiation significantly depends on both the intensity of the shock wave and the shape of the bubble. Based on a series of simulations, the dependence of the threshold Mach numbers of the incident wave on the shape of the bubble is determined. In the plane flow, a moderate elongation of the bubble leads to a significant decrease in the threshold Mach number. In an axisymmetric flow, the lower threshold Mach number is less sensitive to the shape of the bubble, and the most effective detonation initiation is carried out using a spherical bubble. The effect of shock wave focusing makes it possible to achieve successful initiation of detonation at a fundamentally lower intensity of the incident wave compared to direct initiation.

Numerical Modelling of Water Flashing at Sub-Atmopsheric Pressure with a Multi-Regime Approach

The CFD numerical study of the flash boiling phenomenon of a water film was conducted using an Euler–Euler method, and compared to the experiments on the flashing of a water film. The water film is initially heated at temperatures ranging from 34 to 74 ∘C (frim 1 to 41 ∘C superheat), and the pressure is decreased from 1 bar to 50 mbar during the experiments. This paper shows that the experiments could not be correctly modelled by a simple liquid/bubble model because of the overestimation of the drag force above the water film (in the gas/droplet region). The generalised large interface model (GLIM), however, a multi-regime approach implemented in the version 7.0 of the neptune_cfd software, is able to differentiate the water film, where liquid/bubble interactions are predominant from the gas region where gas/droplet interactions are predominant, and gives nice qualitative results. Finally, this paper shows that the interfacial heat transfer model of Berne for superheated liquids could accurately predict the evolution of the water temperature over time.

ABOUT THE POSSIBILITY OF IMPLEMENTING WATER-ALTERNATING-GAS INJECTION USING PUMP-JET SYSTEMS AT THE ARYSTAN FIELD

At the moment, in the Caspian oil and gas region, many fields are in the final stage of development according to the basic version (flooding). According to it, the final oil recovery coefficient often does not reach the design values. Therefore, for such fields, it is necessary to consider the possibility of using various tertiary methods to increase oil recovery.

Measurements of the flow of supercritical pressure carbon dioxide through Venturi flow meter

The Venturi flow meter exhibits relatively low pressure loss, simple design, and low manufacturing costs. This study describes flow rates measurements for supercritical pressure CO2 using the Venturi flow meter with pressure ranging 7.379–7.836 MPa and 5.84–7.272 MPa for in supercritical and gaseous regions, respectively. The flow rates of supercritical pressure CO2 were accurately measured using a Venturi flow meter with a diameter ratio of 0.6468, having large and small diameters of 87.32 mm and 56.48 mm, respectively. The convergent and divergent angles were 21 ° ± 1 ° and 15 ° ± 1 °, respectively. The averaged discharge coefficient of 0.9975 was obtained, which was independent of the pressure ratio. Additionally, the expansion factors were also calculated using the experimental results, which ranged from 0.99976 to 0.99987 and 0.99945–0.99995 for the supercritical and gaseous regions, respectively. The experimental results showed that the Venturi flow meter had uncertainties ranging from 0.1 to 2.8%.

A Study of the Development of Innovative Activities in Oil and Gas Regions Using a Cross-Methodological Approach

A Study of the Development of Innovative Activities in Oil and Gas Regions Using a Cross-Methodological Approach

Substantiation of the prospects to discover large oil and gas accumulations in the Jurassic and pre-Jurassian deposits on the Kara Sea shelf

In order to replenish oil and gas reserves in the medium term and until the end of the century, it will be necessary to study new sediment complexes in promising regions of the country. One of these areas is the Kara Sea shelf, where large and giant gas condensate fields have already been discovered in the Cretaceous deposits, and the Pobeda field has been discovered on the eastern Prinovozemelsky shelf, with an oil deposit in the Lower-Middle Jurassic deposits and gas deposits in the Cretaceous. The article substantiates the prospects for the oil and gas potential of the Jurassic complex in the central part of the South Kara oil and gas region and the strategic need for geological exploration in the Jurassic and pre-Jurassic deposits of the region.

A Numerical Study of an Ellipsoidal Nanoparticles under High Vacuum Using the DSMC Method

The semiconductor and display manufacturing process requires high precision. Therefore, inside the equipment, fine impurity particles affect the yield rate of production. However, since most manufacturing processes are performed under high-vacuum conditions, it is difficult to estimate particle flow with conventional analytical tools. In this study, high-vacuum flow was analyzed using the direct simulation Monte Carlo (DSMC) method, and various forces acting on fine particles in a high-vacuum flow field were calculated. To compute the computationally intensive DSMC method, GPU-based computer unified device architecture (CUDA) technology was used. The force acting on the particles in the high-vacuum rarefied gas region was verified using the results of previous studies, and the results were derived for the difficult-to-experiment region. An ellipsoid shape with an aspect ratio rather than a spherical shape was also analyzed. The change in drag force according to various aspect ratios was analyzed and compared with the results of the spherical shape under the same flow conditions.

Optimal optical Ferris wheel solitons in a nonlocal Rydberg medium.

We propose a scheme for the creation of stable optical Ferris wheel (OFW) solitons in a nonlocal Rydberg electromagnetically induced transparency (EIT) medium. Depending on a careful optimization of both the atomic density and the one-photon detuning, we obtain an appropriate nonlocal potential provided by the strong interatomic interaction in Rydberg states that can perfectly compensate for the diffraction of the probe OFW field. Numerical results show that the fidelity remains larger than 0.96, while the propagation distance has exceeded 160 diffraction lengths. Higher-order OFW solitons with arbitrary winding numbers are also discussed. Our study provides a straightforward route to generate spatial optical solitons in the nonlocal response region of cold Rydberg gases.

Influence of feedstock variability on thermal decomposition of forest residue in a screw feeder for high temperature conversion

Thermochemical conversion of biomass uses high temperatures to break down the feedstock into products. Feeding the reactor, however, can be a challenge that impedes smooth operation of the thermochemical process. The aim of this study was to investigate the effect of feedstock compositional variability on the material deposition on the screw feeder during pyrolysis reactor feeding. Four different sample sets derived from pine (Pinus Taeda), 1st (rich in stem wood), 2nd (rich in bark and needles), 3rd (rich in stem wood), and 4th (whole residues), were used in this study while the reactor was operated at 500 °C. Results showed that the sample set consisted with cleaner feedstock experienced relatively less solid material and tar deposition on the screw feeder. For example, the lowest pseudo accumulation rate was 0.5 pitch/kg-feed for the 3rd set while the highest was 6.7 pitch/kg-feed for the 2nd set showing strong material dependance. Simulations on the temperature prediction inside the auger explored the surface of the auger exposed inside the reactor (ΔTavg = 93 °C) and outlet of the purge gas region (ΔTavg = 126 °C). This temperature drop would likely reduce the formation of deposits on the auger allowing the system for longer periods of continuous operation.

Chemical abundances in Seyfert galaxies – X. Sulphur abundance estimates

ABSTRACT For the first time, the sulphur abundance relative to hydrogen (S/H) in the narrow-line regions of a sample of Seyfert 2 nuclei (Sy 2s) has been derived via direct estimation of the electron temperature. Narrow emission-line intensities from the Sloan Digital Sky Survey (SDSS) Data Release 17 (DR17) [in the wavelength range 3000 < λ(Å) < 9100] and from the literature for a sample of 45 nearby (z < 0.08) Sy 2s were considered. Our direct estimates indicate that Sy 2s have similar temperatures in the gas region where most of the $\rm S\rm ^{+}$ ions are located in comparison with that of star-forming regions (SFs). However, Sy 2s present higher temperature values (${\sim} 10\, 000$ K) in the region where most of the $\rm S\rm ^{2+}$ ions are located relative to that of SFs. We derive the total sulphur abundance in the range of $6.2 \: \lesssim 12+\log (\rm S/H) \: \lesssim \: 7.5$, corresponding to 0.1–1.8 times the solar value. These sulphur abundance values are lower by ∼0.4 dex than those derived in SFs with similar metallicity, indicating a distinct chemical enrichment of the interstellar medium (ISM) for these object classes. The sulphur abundance relative to oxygen (S/O) values for our Sy 2 sample present an abrupt (∼0.5 dex) decrease with increasing oxygen abundance relative to hydrogen (O/H) for the high-metallicity regime [$\rm 12+\log (O/H) \: \gtrsim 8.7)$], what is not seen for the SFs. However, when our Sy 2 estimates are combined with those from a large sample of SFs, we did not find any dependence between S/O and O/H.

Effects of oxidant composition on premixed propane flames in a narrow-gap disk burner at elevated pressures

The effects of length-scale and oxidant composition on the propagation characteristics of premixed propane flames were investigated in a narrow-gap disk burner with a constant volume process (NGDB-CV). First, the oxidant was diluted with N2, and the disk gap was varied. Overall, flame propagation velocity decreased, and flame oscillation became weaker as the N2 concentration increased. In particular, the effect of the increasing N2 concentration on the weakening flame propagation velocity was clearer when the disk gap was sufficiently larger than the quenching distance. The trends in pressure increase varied with the disk gap and could be explained based on the flame propagation velocity and the heat transfer in the burned gas region. In addition, post-combustion with luminosity in the burned gas region was observed within larger disk gaps, and its mechanism was explained. Finally, the effects of oxidant composition on flame oscillation were examined by controlling the concentrations of N2, CO2, and He. It was found that the Lewis number plays an important role in flame oscillation. The ratio of the laminar burning velocity to the Lewis number dominated the oscillation frequency, and the oscillation amplitude was additionally affected by the variation in momentum across the flame. Finally, the mechanism of the flame oscillation was refined.

A Pilot Demonstration of Flaring Gas Recovery during Shale Gas Well Completion in Sichuan, China

Summary As one of the largest emitters in the world, the oil and gas industry needs to apply more effort to greenhouse gas (GHG) reduction. Methane, as a potent GHG, could largely determine whether natural gas could serve as a bridging energy toward a sustainable future. In the past decade, oil and gas companies in China have significantly enhanced casing gas recovery and reduced large volume flaring (>2×104 m3/d). However, the remaining low- to mid-volume flaring gas was left for further recovery. Shale gas production in China has met a surge in the number of drilling wells. Those new wells were characterized by a relatively low gas production rate (<1×106 m3/d) in comparison with shale gas wells in the US. As a result, flaring gas during well completion needs to be recycled or used to enhance the gas recovery rate. In this study, we carried out a pilot demonstration project of flaring gas recovery to reduce GHG emissions in the Weiyuan shale gas region in Sichuan Province, China. We adopted the technical route of dehydration and natural gas compression. The recycled natural gas was transformed into compressed natural gas (CNG) and transported to the nearest CNG station for further use. The inlet gas pressure was between 2.85 and 5.82 MPa, and the outlet pressure was kept stable at around 20 MPa to meet the standard of CNG. The manufactured device also showed sound flexibility with the recovery rate between 523.22 and 1224.38 m3/h, which was 28–157% of the designed capacity. The combination of the molecular sieve with high capacity, post low-pressure dehydration, and the application of hydraulic piston in the compression system have guaranteed the equipment to meet the designed performance. The equipment applied in the pilot demonstration has well matched with the local transportation, gas composition, and surface engineering of the well completion. It has the potential of popularization and application in the shale gas tight gas regions in China. Other technical routes, such as small-scale gas to chemicals or natural gas hydrate, should be considered for industrial application for gas flowing rate less than 2×104 m3/d to ensure a further drive down of methane emission along the value chain.

Two Air Quality Regimes in Total Column NO2 Over the Gulf of Mexico in May 2019: Shipboard and Satellite Views

AbstractThe Satellite Coastal and Oceanic Atmospheric Pollution Experiment (SCOAPE) cruise in the Gulf of Mexico was conducted in May 2019 by NASA and the Bureau of Ocean Energy Management to determine the feasibility of using satellite data to measure air quality in a region of concentrated oil and natural gas (ONG) operations. SCOAPE addressed both technological and scientific issues related to measuring NO2 columns over the outer continental shelf. Featured were nitrogen dioxide (NO2) instruments (Pandora, Teledyne API analyzer) at Cocodrie, LA (29.26°, −90.66°), and on the Research Vessel Point Sur operating off the Louisiana coast with measurements of ozone, carbon monoxide, and volatile organic compounds (VOCs). The findings: (a) all NO2 observations revealed two atmospheric regimes over the Gulf, the first influenced by tropical air in 10–14 May, the second influenced by flow from urban areas on 15–17 May; (b) comparisons of OMI v4 and TROPOMI v1.3 TC (total column) NO2 data with shipboard Pandora NO2 column observations averaged 13% agreement with the largest difference during 15–17 May (∼20%). At Cocodrie, the satellite–Pandora agreement was ∼5%. (c) Three new‐model Pandora instruments displayed a TC NO2 precision of 0.01 Dobson Units (∼5%); (d) regions of smaller, older natural gas operations showed high methane readings from leakage; elevated VOCs were also detected. Neither satellite nor spectrometer captured the magnitude of ambient NO2 variability near ONG platforms. Given an absence of regular air quality monitoring over the Gulf of Mexico, SCOAPE data constitute a baseline against which future observations can be compared.

On the issue of structural tectonic zoning and prospects of the Surkhandarya oil and gas region

On the issue of structural tectonic zoning and prospects of the Surkhandarya oil and gas region

Numerical simulation of ideal and non-ideal under-expanded supersonic jets with adaptive grids

This paper numerically investigates the effect of flow non-ideality on the Mach disk pattern occurring in axisymmetric under-expanded supersonic jets. The explored conditions are found in the non-ideal gas region close to the liquid–vapor saturation curve and the critical point, where involved thermodynamics cannot be accurately described by the ideal gas law. Numerical simulations of steady inviscid compressible flows are carried out by adopting the polytropic ideal gas model and improved Peng–Robinson thermodynamic model, via the open-source computational fluid dynamics code SU2. To properly resolve the Mach disk position and radius, a mesh adaptation procedure is used. An assessment of the most suitable mesh adaptation criteria for the considered ideal and non-ideal flow configurations is carried out, considering isotropic and anisotropic mesh adaptation criteria. The best mesh adaptation criterion for ideal and non-ideal under-expanded jets results to be the anisotropic criterion based on the Hessian of the density and Mach number field. Then, the effects of the flow non-ideality on the Mach disk are investigated by simulating different operating conditions of under-expanded nozzle jets of five different vapors. For nitrogen, oxygen, carbon dioxide, the Mach disk moves downstream and has a smaller radius with a higher level of non-ideality. Conversely, for siloxanes MM and MDM, the Mach disk moves upstream and has a larger radius as the non-ideality of the flows increases.

Contradictions about Sustainability: A Case Study of College Students from Saudi Arabia

The present study offers a window into college students’ views of environmental sustainability in a country that is one of the major oil producers in the world. College students are the main constituents of the country’s programmatic plan (i.e., the 2030 Vision) for restructuring its infrastructure and human capital away from oil and gas production and toward a knowledge and service economy. Thus, their views can influence the success of the plan. In the present study, 430 college students at a university located at the heart of the oil and gas region were surveyed via an online questionnaire. Participants were of Middle Eastern descent. It was found that their beliefs and reported actions were generally supportive of a green economy. However, their beliefs in climate change and specifically in renewable energy did not predict much of their sustainability-based behaviors (e.g., recycling). The latter findings were interpreted as reflecting the internal conflict between embracing change (i.e., a desirable but uncertain future), and resisting change (i.e., a choice that would preserve, at least for some time, the benefits of the fossil fuel economy).

Biased 2 times 2 periodic Aztec diamond and an elliptic curve

We study random domino tilings of the Aztec diamond with a biased 2 times 2 periodic weight function and associate a linear flow on an elliptic curve to this model. Our main result is a double integral formula for the correlation kernel, in which the integrand is expressed in terms of this flow. For special choices of parameters the flow is periodic, and this allows us to perform a saddle point analysis for the correlation kernel. In these cases we compute the local correlations in the smooth disordered (or gaseous) region. The special example in which the flow has period six is worked out in more detail, and we show that in that case the boundary of the rough disordered region is an algebraic curve of degree eight.