Adjacent Domes Research Articles

Flame–Flame Interactions and Jet–Jet Interactions in Gas Turbine Swirl Combustors

Annular combustors are widely used in newly developed aero-engines. Nevertheless, the development of annular combustors requires substantial air supplies and high-power heaters during testing, leading to high experimental costs. To reduce these costs during the design phase, researchers often simplify annular combustors into single-dome configurations using aerodynamic and thermodynamic similarity principles. A fundamental divergence exists between the boundary conditions of annular and simplified single-dome combustors, which is reviewed in this article. It highlights the limitations of single-dome model combustors in accurately representing the crucial features of annular combustors, particularly flame–flame interaction (FFI) and jet–jet interaction (JJI). FFI and JJI existing in annular combustors are observed to result in alternating flow patterns and the superposition of mass and energy transfer between adjacent domes, which can deteriorate flame stabilization and increase NOx emissions. This review emphasizes the characteristics of multi-dome combustors and notes a lack of research comparing single-dome and multi-dome combustors under engine-relevant conditions. Addressing this research gap in the future can better connect fundamental combustion research and engine development, providing more guidance for engine designers.

Morphology, morphogenesis, and molecular characterization of Castula specialis sp. nov. (Ciliophora, Armophorea, Metopida).

The morphology, morphogenesis, and molecular phylogeny of a new metopid ciliate, Castula specialis sp. nov., comprising three strains from geographically distant (China, Mexico, Czech Republic) anoxic freshwater habitats, were studied based on microscopic observation of live and protargol-stained specimens as well as SSU rRNA gene sequence data. The new species is characterized as follows: size invivo 105-220 × 25-70 μm, body oblong to elongated ellipsoidal and asymmetrical; preoral dome distinctly projecting beyond the body; 32-46 adoral membranelles; 31-52 somatic kineties; and 4-7 setae. This study brings the first morphogenetic investigation of a member of the genus Castula. The morphogenesis of the type population (China) of the new species proceeds as in Metopus spp. comprising drastic changes in body shape and a pleurotelokinetal stomatogenesis; however, the main difference is the origin of the opisthe's paroral membrane that derives from all perizonal rows and some adjacent dome kineties. Phylogenetically, the genus Castula is paraphyletic.

Investigations of the effect of the primary hole on ignition performance of a three-dome model combustor with RP-3 liquid aviation fuel

The primary hole exerts a substantial influence on the ignition performance of gas turbine combustors. The current investigation delves into the effect of primary hole jets on the ignition performance of a three-dome model combustor utilizing RP – 3 liquid aviation fuel, providing a comprehensive understanding of the ignition performance. The number of primary holes in the identical dome is considered as two, four, and six, involved in creating different primary hole jets. The limitations in the effectiveness of ignition and propagation have been brought to light by the combustion experiment that was performed under ambient temperature and pressure at a reference velocity ranging from 3 – 8 m/s. Moreover, a validated numerical simulation methodology was employed to investigate the flow field characteristics in the model combustor at a reference velocity of 5.4 m/s. Both experiment and numerical simulation results indicate that the model combustor with four primary holes attains the weakest mutual support between adjacent domes, the highest average radial velocity, and the lowest restrictive effect on the center toroidal recirculation zone.

Investigations of the effect of dome spacing on ignition performance of a model combustor with RP-3 liquid aviation fuel

Dome spacing is one of the most critical factors to affect the ignition performance of the aerospace engine. In this paper, a three-dome model combustor is designed to investigate the effect of dome spacing on ignition performance with RP-3 liquid aviation fuel. The dome spacing considered are 48 mm, 60 mm, 72 mm, respectively, and the effect on ignition performance including ignition and propagation limits are revealed by a combustion experiments under ambient temperature and pressure, and the reference velocity is from 3 m/s to 8 m/s. The ignition performance is evaluated in terms of the fuel/air ratio, at which ignition occurs. The results show that the best ignition performance is achieved when the dome spacing is 60 mm. Furthermore, numerical simulations with validated methodology of non reacting flows inside the combustor have been conducted. The results show that when the dome spacing is 60 mm, the best mutual support between adjacent domes is attained according to the maximum value of mergin rate and dimensionless width of central toroidal recirculation zone. Besides, the restrictive effect of the primary hole jet on the central toroidal recirculation zone is found to be increased with the decrease of dome spacing.

Comparison between Rafidhiya and Shuaiba Domes within the properties of Mishrif Formation in Zubair Field; the implication of structural Geology and petrophysical analyses

The current study combined both concepts of structural geology and petrophysical to understand the structural feature of Mishrif Formation and its implication on the petrophysical characterization of the formation in Shuaiba and Rafidhiya Domes (or culminations) in Zubair Field. Shuaiba and Rafidhiya are adjacent domes and these domes belong to the same Field but the domes separated by saddle may related to Basra – Zubair basement fault.
 The domes have different petrophysical properties of Mishrif Formation; consequently, influenced in water and oil saturation. Therefore, the study tries to understand the structural and petrophysical position of Mishrif Formation of the domes. The structural analysis included geometric and genetic analysis, whereas petrophysical analysis used open hole logs interpretation to determine the petrophysical characteristics (especially the distribution of porosity, permeability, and water saturation.
 It was concluded that may a variation in porosity and permeability of Mishrif Formation for Shuaiba and Rafidhiya domes because each dome was formed by a different folding mechanism effected on the petrophysical properties. The structural geology analysis detects that may be Shuaiba dome formed by bending fold mechanism (vertical force of salt structure), while Rafidhiya dome by buckling fold mechanism (parallel force of collision of Arabian and Eurasian plate). These mechanisms may directly be affected in permeability distribution, and consequently on oil and water saturation of Mishrif Formation. Thus, Shuaiba Dome has thinning in hinge area and extensional force leads to create fractures and karst phenomena, and as a result, high permeability in upper Mishrif. On the contrary, Rafidhiya Dome has a thickening feature and there is no indication of karst phenomena and low permeability. Therefore, the Mishrif of Shuaiba dome permeable and oil-saturated, while, it flooded with water in Rafidhiya Dome. The disconnection in reservoir pressure confirmed by difference in initial reservoir pressure of Mishrif Formation of Shuaiba Dome and recent reservoir pressure of Mishrif Formation of Rafidhiya Dome

Superimposed folding and thrusting by two phases of mutually orthogonal or oblique shortening in analogue models

Orogens may suffer more than one phase shortening resulting in superposition of structures of different generations. Superimposition of orthogonal or oblique shortening is studied using sandbox and centrifuge modelling. Results of sand models show that in orthogonal superimposition, the two resulting structural trends are approximately orthogonal to each other. In oblique superimposition, structures trend obliquely to each other in the relatively thin areas of the model (foreland), and mutually orthogonal in areas where the model is thickened during the first phase of shortening (i.e. the hinterland). Thrusts formed during the first shortening phase may be reactivated during the later shortening phase. Spacing of the later phase structures is not as wide as expected, considering they across the pre-existing thickened wedge. Superposition of structures results in formation of type 1 fold interference pattern. Bedding is curved outwards both in the dome and basin structures. Folded layers are dipping and plunging outwards in a dome, while they are dipping and plunging inwards in a basin. In the areas between two adjacent domes or basins (i.e. where an anticline is superimposed by a syncline or a syncline is superimposed by an anticline), bedding is curved inwards, and the anticlines plunge inwards and the synclines outwards. The latter feature could be helpful to determine the age relationship for type 2 fold interference pattern. In tectonic regions where multiple phases of shortening have occurred, the orogenic-scale dome-and-basin and arrowhead-shaped interference patterns are commonly formed, as in the models. However, in some areas, the fold interference pattern might be modified by a later phase of thrusting. Similar to models results, superimposition of two and/or even more deformation phases may not be recorded by structures all over the tectonic area.

Effect of interdome spacing on the resonance properties of plasmonic nanodome arrays for label-free optical sensing

In this paper, we report on experimental and theoretical studies that investigate how the structural properties of plasmonic nanodome array devices determine their optical properties and sensing performance. We examined the effect of the interdome gap spacing within the plasmonic array structures on the performance for detection of change in local refractive index environment for label-free capture affinity biosensing applications. Optical sensing properties were characterized for nanodome array devices with interdome spacings of 14 nm, 40 nm, and 79 nm, as well as for a device where adjacent domes are in contact. For each interdome spacing, the extinction spectrum was measured using a broadband reflection instrumentation, and finite-difference-time-domain (FDTD) simulation was used to model the local electric field distribution associated with the resonances. Based on these studies, we predict that nanodome array devices with gap between 14 nm to 20 nm provide optimal label-free capture affinity biosensing performances, where the dipole resonance mode exhibits the highest overall surface sensitivity, as well as the lowest limit of detection.

Colocalization of thin-walled dome regions with low hemodynamic wall shear stress in unruptured cerebral aneurysms

Wall shear stress (WSS) plays a role in regulating endothelial function and has been suspected in cerebral aneurysm rupture. The aim of this study was to evaluate the spatial relationship between localized thinning of the aneurysm dome and estimated hemodynamic factors, hypothesizing that a low WSS would correlate with aneurysm wall degeneration. Steady-state computational fluid dynamics analysis was performed on 16 aneurysms in 14 patients based on rotational angiographic volumes to derive maps of WSS, its spatial gradient (WSSG), and pressure. Local dome thickness was estimated categorically based on tissue translucency from high-resolution intraoperative microscopy findings. Each computational model was oriented to match the corresponding intraoperative view and numerically sampled in thin and normal adjacent dome regions, with controls at the neck and parent vessel. The pressure differential was computed as the difference between aneurysm dome points and the mean neck pressure. Pulsatile time-dependent confirmatory analysis was carried out in 7 patients. Matched-pair analysis revealed significantly lower levels of WSS (0.381 Pa vs 0.816 Pa; p<0.0001) in thin-walled dome areas than in adjacent baseline thickness regions. Similarly, log WSSG and log WSS×WSSG were both lower in thin regions (both p<0.0001); multivariate logistic regression analysis identified lower WSS and higher pressure differential as independent correlates of lower wall thickness with an area under the curve of 0.80. This relationship was observed in both steady-state and time-dependent pulsatile analyses. Thin-walled regions of unruptured cerebral aneurysms colocalize with low WSS, suggesting a cellular mechanotransduction link between areas of flow stasis and aneurysm wall thinning.

Archean gravity-driven tectonics on hot and flooded continents: Controls on long-lived mineralised hydrothermal systems away from continental margins

We present the results of two-dimensional numerical modelling experiments on the thermal evolution of Archean greenstones as they sink into a less dense, hot and weak felsic crust. We compare this thermal evolution to that obtained via the analysis of isotopic data and fluid inclusion microthermometry data obtained in the Paleoarchean to Mesoarchean Warrawoona Synform (Eastern Pilbara Craton, Western Australia). Our numerical experiments reveal a two-stage evolution. In the first stage, cooling affects zones of downwelling as greenstone belts are advected downward, whereas adjacent domes become warmer as deep and hot material is advected upward. We show that this is consistent with stable isotopes data from the Warrawoona Synform, which reveal an early episode of seafloor-like alteration (90–160°C) strongly focused along steeply dipping shear zones. In a second long-lived stage, lateral heat exchanges between domes and basins dominate the system as domes cool down while downwelling zones become increasingly warmer. In the Warrawoona greenstone belt, stable isotopes in gold-bearing quartz veins post-dating the sagduction-related vertical fabrics reveal that rock–fluid interaction occurred at much higher temperatures (234–372°C) than seafloor-like alteration. We propose that emplacement of thick and dense continental flood basalts, on flooded hot and weak continental plates, led to conditions particularly favourable to hydrothermal processes and the formation of mineral deposits. We further argue that sagduction was able to drive crustal-scale deformation in the interior of continents, away from plate margins. On largely flooded continents, sagduction-related shear zones acted as fluid pathways promoting gold mineralisation far away from active plate boundaries, continental rift zones or collisional mountain belts.

Surface-enhanced Raman nanodomes

We demonstrate a surface-enhanced Raman scattering (SERS) substrateconsisting of a closely spaced metal nanodome array fabricated on flexible plasticfilm. We used a low-cost, large-area replica molding process to produce atwo-dimensional periodic array of cylinders that is subsequently overcoated withSiO2 and silver thin films to form dome-shaped structures. Finite element modeling was used toinvestigate the electromagnetic field distribution of the nanodome array structureand the effect of the nanodome separation distance on the electromagnetic fieldenhancement. The SERS enhancement from the nanodome array substrates wasexperimentally verified using rhodamine 6G as the analyte. With a separationdistance of 17 nm achieved between adjacent domes using a process that is preciselycontrolled during thin film deposition, a reproducible SERS enhancement factor of1.37 × 108 was demonstrated. The nanoreplica molding process presented in this work allowsfor simple, low-cost, high-throughput fabrication of uniform nanoscale SERSsubstrates over large surface areas without the requirement for high resolutionlithography or defect-free deposition of spherical microparticle monolayer templates.

The waning stage of a greenstone belt: The Mesoarchaean Mosquito Creek Basin of the East Pilbara, Western Australia

The Mosquito Creek Basin stands apart in the Archaean granite–greenstone terrane of the east Pilbara Craton because of the rectangular outcrop but crescent-shaped subcrop, and its composition of low-grade metamorphic mainly turbiditic clastic sedimentary rocks. These sediments belong to the c. 2.9 Ga Mosquito Creek Formation. Tectonic interpretations of the basin have varied from a simple synclinorium, to an accretionary prism, an extensional passive margin, and more recently into a rift basin separating the Kurrana Terrane from the East Pilbara Terrane (EPT). Combined sedimentological and structural–geological investigations show coarse-clastic fan-delta marginal facies with stacked unconformities, rimming an E–W basin centre with predominantly finer-grained mass flow-dominated sediments. A N–S traverse therefore contains a complete cross-section of the Mosquito Creek Basin, shortened to about 50% of its original width by tight folding and thrusting. The basin fill shows one major FU sequence from fan-delta sandstone to distal turbidites, unconformably overlying an older, partially preserved clastic sequence of comparable facies. A large slump unit occupies the basin axis. The unconformities along the margins interfere with folding of the sediments which also influenced basin-centre turbiditic palaeocurrents. The basin is interpreted as a near-symmetrical, underfilled, compressional, intramontane, clastic sedimentary basin unconformably superposed on a volcanic greenstone belt rock assemblage with enclosed low-angle shear zones. Compression started during sedimentation under conditions of net subsidence within a rim syncline between adjacent domes. This occurred after phases of low-angle extensional and compressional deformation of the substrate not related to the present-day geometry of the granitoid domes. The geological setting of the Mosquito Creek Basin does not differ fundamentally from that of other adjacent E–Woriented greenstone belts of the EPT. The basin is inferred to represent the last, stratigraphically uppermost, and because of subsequent erosion rarely preserved, stage of greenstone belt evolution.

ON THE MECHANISM OF DECUSSATE PHYLLOTAXIS: BIOPHYSICAL STUDIES ON THE TUNICA LAYER OF VINCA MAJOR

Phyllotaxis theory typically assumes that an acropetal influence from recently formed leaves acts on the apical dome to initiate new leaves. Biophysical theory postulates that established plant organs elongate because their primary walls, particularly those in the organ surface layer, are transversely reinforced by cellulose to give the organ overall hoop reinforcement. These two postulates are combined here in a biophysical theory for phyllotaxis. The essential acropetal influence from young leaves is proposed to be the stretching of the adjacent dome tissue by the growth of leaf bases. Cytoskeletal responses on the dome produce reinforcement patterns which initiate new hoop reinforced leaves. Growth of these leaves remodels the dome for the next round of organs. Data pertinent to this theory are presented here for Vinca major. The surface (tunica) layer of the apical dome was isolated by paradermal cuts. Using polarized light, the cellulose alignment in this surface layer was determined, cell by cell, for various stages of the plastochron. The growing dome is typically elliptical, with the major axis shifting by 90° during each plastochron. The periphery of the dome always has cellulose oriented parallel to its margin; the central region, when the major axis is pronounced, has reinforcement normal to this axis. During the plastochron this reinforcement pattern is modified, by plausible biophysical mechanisms, to account for the three major activities of the dome: 1) production of a hoop‐reinforced leaf at each end of the ellipse, 2) formation of a hoop‐reinforced stem segment, 3) revision of dome structure to produce the same initial reinforcement pattern as at the start of the plastochron, but at 90°.

A theory for inflorescence development and flower formation based on morphological and biophysical analysis in Echeveria

Floral development is generally viewed as involving interactions between recently made organs and generative activity on the apical dome; one set of floral organs is thought to induce the next. To investigate such interactions, flowering in Echeveria derenbergii (J. Purpus) was studied at two levels of structure. At the larger, morphological, level the inflorescence apex is shown to have simple cyclic development. Seen from above, it elongates horizontally, then forms a transverse cleft to demarcate a flower primordium in one of two rows. The meristem then elongates at 90° to its previous axis, also horizontally, and demarcates a flower in the other row. Activity on the apical surface correlates well with the nature and activity of adjacent sub-apical organs. For example, the 90° shifts in elongation of the meristem correlate with that tissue's being attached, laterally, to successive large growing bracts whose bases lie at 90°. Also, on the flower primordium, the five sepals arise in a spiral sequence which correlates with one of increasing age, since formation by the cleft, of the edges of the primordium.The second level of study was to test whether the developmental correlations could have a biophysical explanation. By biophysical theory, organs arise where the dome surface is structurally predisposed to bulge. This is a function of the cellulose reinforcement pattern in the surface. Successive patterns of cellulose reinforcement in isolated surface layers from floral organs were determined using polarized light. This was done for the cyclic activity of the inflorescence meristem and the development of the flower. The results indicate that patterns of cellulose reinforcement on the apical dome surface could lead to the production of organs, through local promotion of bulging of the tunica. Subsequent growth of the base of each organ stretches the adjacent dome tissue in a directional fashion. Cytoskeletal responses of these stretched cells lead to new cellulose alignments on the dome which generate the reinforcement pattern for the next round of organs.

The structure and metamorphism of the mantling Karagwe–Ankolean sediments of the Ntungamo gneiss dome and their time-relation to the development of the dome

The Ntungamo gneiss dome has a quartzo-feldspathic core that has an abrupt and generally concordant margin with the overlying Pre-Cambrian Karagwe–Ankolean metasediments. The sediments, which dip off the dome on all sides, lie in synclinal belts around it and between the Ntungamo dome and adjacent domes. There is no good evidence of the intrusive character of the granitic rocks of the dome, and it is suggested that they are deformed Karagwe-Ankolean basement. The deformation history of the metasediments is divisible into two phases separated by a time-interval during which porphyroblasts of andalusite, kyanite, and staurolite developed. The schistosity of the sediments was formed in the first phase and was deformed in the second; the dome and synclines were produced in the second phase. This interpretation differs from earlier ones in which all the Karagwe-Ankolean structures were described as forming in one deformational episode, the schistosity being produced during dome-forming movements that were themselves the result of granite intrusion.