Intermediate Duct Research Articles

Funnel and Vessel-Duct Adenoma Breast

Duct adenoma appears as an exceptionally discerned, benign tumefaction comprised of distorted glandular articulations circumscribed within a fibrous tissue capsule and intermingled within a sclerotic stroma. Initially scripted Azzopardi and Salm in 1984, the adenomatous lesion is configured of miniature and intermediate ducts disseminated within peripheral breast tissue. Alternative nomenclature of sclerosing papilloma is not recommended.

Experimental investigation of intermediate compressor duct

The intermediate duct connects high-pressure and low-pressure compressors. It comprises flow channels and struts that fix the relative positions of the hub and shroud. The mechanism of airflow movement around the struts in the downstream intermediate ducts is experimentally investigated based on four cases, including two types of struts and two shapes of meridional flow channels. The measurement parameters of the intermediate duct under the same conditions are measured in the wind tunnel, including the total pressure loss coefficient at the outlet and axial wall pressure distribution. In addition, the flow characteristics near the wall are obtained through the oil flow test, and the frequency of the shedding vortex is captured by the dynamic pressure probes. The results demonstrate that the strut and channel with the modified profile can reduce the total pressure loss and eliminate wake oscillation by changing the flow characteristic. The total pressure losses of the modified profile at 0.2, 0.25, 0.3, 0.35, 0.4, and 0.45 Ma conditions are reduced by 60%, 63%, 83%, 89%, 85%, and 87%, respectively.

Review on the aerodynamics of intermediate compressor duct

In a turbofan engine, the air is brought from the low to the high-pressure compressor through an intermediate compressor duct. Weight and design space limitations impel to its design as an S-shaped. Despite it, the intermediate duct has to guide the flow carefully to the high-pressure compressor without disturbances and flow separations hence, flow analysis within the duct has been attractive to the researchers ever since its inception. Consequently, a number of researchers and experimentalists from the aerospace industry could not keep themselves away from this research. Further demand for increasing by-pass ratio will change the shape and weight of the duct that uplift encourages them to continue research in this field. Innumerable studies related to S-shaped duct have proven that its performance depends on many factors like curvature, upstream compressor’s vortices, swirl, insertion of struts, geometrical aspects, Mach number and many more. The application of flow control devices, wall shape optimization techniques, and integrated concepts lead a better system performance and shorten the duct length. This review paper is an endeavor to encapsulate all the above aspects and finally, it can be concluded that the intermediate duct is a key component to keep the overall weight and specific fuel consumption low. The shape and curvature of the duct significantly affect the pressure distortion. The wall static pressure distribution along the inner wall significantly higher than that of the outer wall. Duct pressure loss enhances with the aggressive design of duct, incursion of struts, thick inlet boundary layer and higher swirl at the inlet. Thus, one should focus on research areas for better aerodynamic effects of the above parameters which give duct design with optimum pressure loss and non-uniformity within the duct.

Investigation of pressure drop in flexible ventilation ducts under different compression ratios and bending angles

Due to the large degree of freedom in terms of design and installation, flexible ventilation ducts are commonly used in ventilation systems. However, excessive use of flexible ducts may lead to greater pressure drop and higher energy consumption. This study conducted experimental measurements to characterize the pressure drop in flexible ventilation ducts with different compression ratios and bending angles. This investigation first measured the pressure drop in straight flexible ducts with four compression ratios under various airflow rates. The calculated friction factor for the straight flexible ducts was negatively associated with the compression ratio. Next, the pressure drops in single-bend flexible ducts with various bending angles from 30° to 150° were measured under various airflow rates. The calculated loss coefficient of the bend increased with the bending angle for single-bend flexible ducts. Finally, the influence of the intermediate duct length on the pressure drop across two bends was experimentally investigated. When the length of the intermediate duct was greater than eight times the inner diameter, the pressure drop across a double-bend flexible duct could be calculated from the friction factors and loss coefficients with a relative error less than 1%. The data obtained in this study can be used to calculate the total pressure loss in flexible ventilation ducting systems in buildings.

Reliability Providing Approach for Structurally- Parametrical Optimization Results of an “Aggressive” Intermediate Duct of the Bypass Gas-Turbine Engine

Limit assessment for the new optimization approach is carried out. This approach allows us to optimize the gas turbine duct elements by using the structural analysis and computational fluid dynamics methods, and to minimize the necessary number of CFD computations. Obtained results were verified and confirmed by experimental aerodynamic investigation.

Morphology and ultrastructure of the Malpighian tubules in Kolla paulula (Hemiptera: Cicadellidae)

Four Malpighian tubules of the leafhopper Kolla paulula (Walker) emerge from the junction of the midgut and hindgut, with terminal ends united in pairs and attached to half of the rectum. Each tubule has five structurally distinct regions: a thin anteriormost region, taking part in the formation of the filter chamber; a smooth and short intermediate duct; a long nodulose proximal segment; a glandular distal segment; and a long, thin and undulated terminal segment. The proximal region contains numerous hollow spherical nodules which are regularly arranged and form a spiral pattern. Its cytoplasm is packed with extensive rough endoplasmic reticulum and secretory granules. Clusters of fine electron-dense granules, glycogen granules and condensing vacuoles are prominent. This suggests that the proximal region is involved in secretion. Microorganisms are found in the cytoplasm and lumen of the proximal segment. The distal segment is rod-shaped, with cells filled with vacuoles containing hollow and honeycomb-surfaced microspheres known as “brochosomes”, and four different stages of brochosome-development can be recognized. The terminal segment cells possess well-developed apical microvilli and basal infoldings associated with mitochondria. Rough endoplasmic reticulum, abundant mitochondria, and intracellular canaliculi densely packed with long microvilli are observed through the cytoplasm. These characters indicate the terminal segment is probably involved in secretion and ion transport.

41. A case of salivary gland adenoma with ductal differentiation with morphological resemblance to normal striated ducts

Background WHO classification of salivary gland adenomas includes a morphological spectrum based on cellular and stromal components. Pure ductal adenoma is not a valid entity in the current WHO classification. Clinical data A 73 year old woman underwent a parotidectomy with clinical suspicion of pleomorphic adenoma. On follow up at 32 months, there was no evidence of recurrence or metastasis. Pathological findings Grossly a relatively circumscribed 22 mm tumour was identified. Histologically it was composed of ductal structures lined by columnar cells with eosinophilic cytoplasm and no cytological or architectural features of malignancy. The ducts showed a great resemblance to normal striated ducts. On immunohistochemistry the lesional cells exhibited an epithelial phenotype (positive for AE1/3, CK7, and CEA) and immunostains for myoepithelial markers failed to demonstrate a myoepithelial component. Electron microscopy attributed an epithelial nature to the tumour with ultrastructural features suggestive of intermediate ducts. Discussion This case demonstrated features of a benign neoplasm, although difficult to subtype. Entities including pleomorphic adenoma, oncocytoma, basal cell and canalicular adenoma were considered in the differential diagnosis. On immunomorphological grounds, there was a great resemblance to striated ducts. A series (6 cases) of striated duct adenomas has been previously reported in the literature. The current tumour had an essential histological resemblance to those cases, although EM failed to prove a definite striated duct origin. Conclusion We report a case of salivary gland neoplasm with ductal differentiation intermediate between striated and intercalated ducts. We believe pure ductal salivary gland adenomas are uncommon but do exist and should be considered in the differential diagnosis if appropriate morphological features are identified.

Effect of inlet conditions on compressor intermediate duct

With further development of the turbofan aero-engine, the compressor intermediate duct can no longer be considered to merely perform the service function of transporting fluid from low-pressure component to high-pressure stage. Especially for the practical compressor intermediate duct with inclined uncambered struts, the high-curvature geometry, great internal pressure gradient, and strong three-dimensional effect make it extremely sensitive to the real inflow conditions, which would not be applicable to the previous research methods based on two-dimensional axisymmetric assumption. In this paper, numerical investigation was conducted about the influence of inflow conditions on a compact compressor intermediate duct with eight inclined struts and numerical approach was validated by comparison with experiment data and the computation accuracy of flow field details was studied by different grid settings. This study deeply explored the flow mechanism and aerodynamic performance about how the pre-swirl angle, inlet Mach number, and distorted total pressure effect of the compressor intermediate duct flow field. The results indicate: (1) for a compact compressor intermediate duct, the proper predication for the flow separation due to an aggressive geometry depends on the radial computing grid strongly, (2) the leeward side of the uncambered strut is extremely sensitive to the pre-swirl inflow, and the existence of backflow and exit non-uniformity is caused by the pre-swirl inflow, (3) the airflow adjacent to the casing wall is more sensitive to the inlet Mach number, whose increase will strengthen the exit non-uniformity and interaction between the strut wake and endwall boundary layer, and (4) the distorted inflow through compressor intermediate duct channel will be amplified because of the compact geometry.

Ultrastructural study of the kidney in the coelacanth Latimeria chalumnae (Rhipidistia: Coelacanthini).

The morphology of the nephrons of the coelacanth Latimeria chalumnae was investigated by electron microscopy. Each nephron is composed of a large renal corpuscle with well vascularized glomerulus, ciliated neck segment, proximal tubule divided into first and second proximal segments, ciliated intermediate segment, distal tubule, collecting tubule, and duct. The podocytes of visceral epithelium contain large bi-lobed nuclei and their surface membranes pinch off vesicles into the cytoplasm. The processes of the podocytes give rise to pedicels that enclose narrow filtration slits. The endothelium of glomerular capillaries is attenuated and fenestrated. The short cytoplasmic processes of mesangial cells do not penetrate deeply into the sub-endothelial lamina. The glomerular basement membrane is about 286 nm in thickness. The pedicels also arise from podocyte cell bodies, and are connected by diaphragms and enclose slits, which open into narrow urinary spaces between podocytes. The cuboidal cells of the short neck segment display cilia with a characteristic pattern of 9+2 microtubules. The first proximal tubule segment differs from the second proximal segment in having densely packed microvilli, prominent endocytotic-lysosomal apparatus, and numerous basal membrane infoldings associated with mitochondria. The lateral cell membranes like those of other segments are straight and joined by desmosomes and apical adhering and tight junctions. The distal tubules display few short luminal microvilli and numerous basal mitochondria. The distal tubule, collecting tubule and duct are devoid of intercalated cells. The ultrastructure of the L chalumnae nephrons correlates well with their osmoregulatory function and resembles that of freshwater rainbow trout.

Aerodynamic Interactions Between a High-Pressure Turbine and the First Low-Pressure Stator

The accurate prediction of turbines performance and flow fields requires the assessment of unsteady numerical simulations. This paper presents a numerical study on the interaction between a single-stage high-pressure turbine and the first vane row of a low-pressure turbine. It focuses on the simulation of the flow within the interturbine duct and the loss generated in the downstream low-pressure vane. Former experiments provided steady and unsteady measurements in the interturbine duct and after the low-pressure vane. A 3D unsteady Reynolds-averaged Navier–Stokes (URANS) approach with phase-lagged boundary conditions is used to characterize the unsteady periodic effects in the interturbine channel and downstream in the low-pressure vane. For the numerical study, two different configurations are considered: a single-stage high-pressure turbine configuration and a high-pressure rotor coupled with a low-pressure vane. For the second one, two inlet boundary conditions are implemented upstream of the rotor: a circumferentially uniform boundary condition and a circumferentially nonuniform rotating boundary condition. The resulting flow fields are compared within the intermediate duct. A harmonic Fourier analysis is carried out to underline the effects of the high-pressure rotor. An unsteady Adamczyk decomposition of the flow field within the duct gives the influence of the different components and the levels of unsteadiness. Comparisons with experimental data show a reasonable good agreement.

The Effect of Rotor Tip Clearance Size onto the Separated Flow Through a Super-Aggressive S-Shaped Intermediate Turbine Duct Downstream of a Transonic Turbine Stage

The demand for a further increased bypass ratio of aero engines will lead to low pressure turbines with larger diameters, which rotate at a lower speed. Therefore, it is necessary to guide the flow leaving the high pressure turbine to the low pressure turbine at a larger diameter without any loss generating separation or flow disturbances. Due to costs and weight, this intermediate turbine duct (ITD) has to be as short as possible. This leads to an aggressive (high diffusion) and, furthermore, to a super-aggressive s-shaped duct geometry. In order to investigate the influence of the blade tip gap size on such a high diffusion duct flow a detailed test arrangement under engine representative conditions is necessary. Therefore, the continuously operating Transonic Test Turbine Facility (TTTF) at Graz University of Technology has been adapted: An super-aggressive intermediate duct is arranged downstream of a transonic high pressure (HP)-turbine stage providing an exit Mach number of about 0.6 and a swirl angle of –15 deg. A second low pressure (LP)-vane row is located at the end of the duct and represents the counter-rotating low pressure turbine at a larger diameter. A following deswirler and a diffuser are the connection to the exhaust casing of the facility. In order to determine the influence of the blade tip gap size on the flow through such a super-aggressive s-shaped turbine, duct measurements were conducted with two different tip gap sizes, a 1.5% span (0.8 mm) and a 2.4% span (1.3 mm). The aerodynamic design of the HP-turbine stage, ITD, LP-vane, and the de-swirler was done by MTU Aero engines. In 2007 at the ASME Turbo Expo, the influence of the rotor clearance size onto the flow through an aggressive ITD was presented. For the present investigation, this aggressive duct has been further shortened by 20% (super-aggressive ITD) so that the flow at the outer duct wall is fully separated. This paper shows the influence of the rotor tip clearance size on to this separation. The flow through this intermediate turbine duct was investigated by means of five-hole-probes, static pressure taps, boundary layer rakes, and oil flow visualization. The oil flow visualization showed the existence of vortical structures within the separation where they seem to be imposed by the upstream HP-vanes.

Turbulent boundary layer separation control and loss evaluation of low profile vortex generators

The present paper analyses the results of a detailed experimental study on low profile vortex generators used to control the turbulent boundary layer separation on a large-scale flat plate with a prescribed adverse pressure gradient, typical of aggressive turbine intermediate ducts. This activity is part of a joint European research program on Aggressive Intermediate Duct Aerodynamics (AIDA). Laser Doppler Velocimetry and a Kiel total pressure probe have been employed to perform measurements in the test section symmetry plane and in cross-stream planes to investigate the turbulent boundary layer, with and without control device application. Velocity fields, Reynolds stresses, and total pressure distributions are analysed and compared for the controlled and non controlled flow conditions to characterize the mean flow behaviour. The detail and the accuracy of the measurements allow the evaluation of the deformation works of the mean motion in the test section symmetry plane. Normal and shear contributions of viscous and turbulent deformation works have been analysed and employed to explain the distribution of the total pressure loss. For the controlled flow the discussion of the flow field is extended considering the effects of the vortex generated in the cross-stream planes. The experimental data allow the evaluation of the global amount of losses, considering a balance of total pressure fluxes in the different measuring planes.

Salivary glands of Amblyomma cajennense (Acari: Ixodidae): a histological and an ultrastructural overview

The present study on the salivary glands of semi-engorged Amblyomma cajennense females has identified the various cell types present in this tissue and allowed its morphohistochemical characterization. Marking techniques were applied to detect polysaccharides (PAS), proteins (bromophenol blue), lipids (Nile blue) and calcium (von Kossa), as well as those of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results obtained by TEM showed and confirmed that these individuals' glands are also formed by round acini that are connected to the common excretory duct through acinar and intermediate ducts. Histological data as well as ultrastructural ones showed that the glands are formed by types I, II and III acini. In this study with salivary glands polysaccharides, proteins, lipids and calcium were observed in the cytoplasm and/or cell secretion granules-both free or forming complexes, as the intensity of the marking varied according to the cell as well as the type of acini analyzed, showing the structural and functional complexity of the tick salivary glands, characteristics that give the multifunctional character to this organ.

Separators for removal of solid particles from the hot intermediate superheating steam ducts of high-power generator units

The operation of three types of separators for the removal from the hot intermediate superheater steam duct of slag particles which reach the medium pressure part of the turbine from the steam generator. Results on the industrial operation of one of these systems are examined. Possible modifications of the separators are formulated.

Analysis of the development of damage in a welded junction in the hot intermediate superheat steam duct of 800-MW generator units

Data from a metallographic study of a damaged weld junction in a hot intermediate superheat steam duct and a computational model for crack development (in the damaged zone) by a creep mechanism are described. Anumerical calculation confirms the possibility of crack development to the known final size over a time of approximately 15,000 h, which corresponds to the operating time for the steam duct from the last time it was inspected until the time of a through fault, under conditions such that a 2.5-mm-deep surface crack (with a length of ∼50 mm along the surface) had been overlooked during this last inspection.

Velocity and turbulence measurements in a separating boundary layer with and without passive flow control

The present paper reports the results of a detailed experimental study on low profile vortex generators (VGs) used to control boundary layer separation on a large-scale flat plate with prescribed adverse pressure gradients. This activity is part of a joint European research program on Aggressive Intermediate Duct Aerodynamics. The inlet turbulent boundary layer and the pressure gradient over the flat plate are representative of aggressive turbine intermediate ducts. By regulating the inclination of the wall opposite to the flat plate, different pressure gradients, typical of turbine intermediate ducts, can be obtained. To avoid separation on the movable wall, boundary layer suction is applied. Previous measurements showed the effectiveness of VGs in delaying separation and revealed their optimum configuration for the different prescribed pressure gradients. In the present work, laser Doppler velocimetry (LDV) is applied to the most significant pressure gradient case, in order to obtain a more thorough knowledge of the near-wall flow field. Velocity and turbulence profiles are determined up to the near-wall region in order to provide an in-depth analysis of turbulent boundary layer at separation conditions, with and without application of control devices. LDV allowed high spatial resolution and accurate statistical analysis of the boundary layer velocities. The results show velocity and turbulence profiles typical of separated turbulent boundary layers for the baseline case, and non-conventional unseparated boundary layer profiles when VGs are installed on the flat plate.

Amblyomma cajennense (Acari: Ixodidae): Salivary gland cells of partially engorged females ticks and the production of lipid by their mitochondria

Morphologically, the salivary glands of ticks are paired structures consisting of a secretory and an excretory portion, lacking a reservoir for the storage of the secretion. The secretory portion is composed in females by cells that form acini classified into the types I, II, and III. The excretory possess a major duct, from which arise several intermediate ducts that then subdivide to form the canaliculi or acinal tubules, which end at the acini from where they collect the secretion. The present study describes the ultrastructural changes that occur in the mitochondria of cells of the acini I, II, and III in the salivary glands of partially engorged females of the Cayenne tick Amblyomma cajennense. The results show that this organelle exhibits completely disarrayed crests due to the presence of lipidic material inside the matrix and between the crests, thus demonstrating their participation in the production of the lipids that would be used structurally by the cells. These organelles with ultrastructural changes were denominated derived mitochondria.

Mammary ductal epithelial cell hyperproliferation and hyperplasia induced by a nutritional stress diet containing four components of a western-style diet.

We have studied effects of several nutrients on the proliferation of mammary ductal epithelial cells in C57BL/6J virgin female mice, using morphometry and [3H]dT in vivo labeling. A nutritional stress diet was given based on the AIN-76A semi-synthetic diet modified to contain four significant risk factors of a Western-style diet: high fat and phosphate and decreased calcium and vitamin D. The numbers of large, intermediate and terminal ducts and proliferating epithelial cells in mammary glands were assayed in control and stress diet groups. An increased number of mammary ducts and increased number of proliferating cells were found at the level of the small terminal ducts, a cancer-prone region in the mammary gland in the stress diet group compared to the control group after 20 weeks of diet administration. Thus, mammary terminal ductal hyperproliferation, expansion in the size of the proliferative epithelial cell compartment and excessive duplication of mammary ductal epithelial cells were found after this Western-style diet containing decreased dietary calcium and vitamin D. These changes are similar to those developing in colonic epithelium of mice maintained on the same diets and during chemically induced colonic carcinogenesis.

Morphology and classification of subdivisions of the intrahepatic vascular and biliary systems in sheep

Tensol casts and histology were used to demonstrate sub-divisions of the portal and hepatic veins, and arterial and biliary systems. Portal and hepatic venous subdivisions were most readily identified. Based upon size, location, sequence of branching and histological characteristics a nomenclature for the sub-divisions of the portal vascular system was proposed. The names of distributing, primary, terminal, secondary (long and short) and tertiary veins were adopted to identify portal veins branches. The same criteria allowed the identification of three hepatic vein branches, central, sublobular and hepatic; the central hepatic veins and to a much lesser extent the sublobular hepatic veins drained the sinusoids. Casts of the arterial system demonstrated the arterial blood supply to the biliary system, to the sinusoids and portal vein vasa vasorum but they were of little use in identifying subdivisions. Arterial subdivision identification is possible by using accompanying portal veins as morphological markers and designating the subdivision after the vein. This approach is also applicable to the biliary system and provides a more accurate means of subdivision identification than does the broader division into ductules, intermediate and large ducts.