Perpendicular Trajectory Research Articles

Prestall Behavior of a Transonic Axial Compressor Stage via Time-Accurate Numerical Simulation

Computational fluid dynamics calculations using high-performance parallel computing were conducted to simulate the prestall flow of a transonic compressor stage, NASA compressor Stage 35. The simulations were run with a full-annulus grid that models the 3D, viscous, unsteady blade row interaction without the need for an artificial inlet distortion to induce stall. The simulation demonstrates the development of the rotating stall from the growth of instabilities. Pressure rise performance and pressure traces are compared with published experimental data before the study of flow evolution prior to the rotating stall. Spatial fast Fourier transform analysis of the flow indicates a rotating long-length disturbance of one rotor circumference, which is followed by a spike-type breakdown. The analysis also links the long-length wave disturbance with the initiation of the spike inception. The spike instabilities occur when the trajectory of the tip clearance flow becomes perpendicular to the axial direction. When approaching stall, the passage shock changes from a single oblique shock to a dual shock, which distorts the perpendicular trajectory of the tip clearance vortex but shows no evidence of flow separation that may contribute to stall.

Dermal collagen organization in Bufo ictericus and in Rana catesbeiana integument (Anuran, Amphibian) under the evaluation of laser confocal microscopy

Collagen structural organization plays an important role in the mechanical property of the vertebrate integument. Bufo ictericus and Rana catesbeiana integument was investigated by light microscopy and laser confocal microscopy. Collagenous elements of the dermis were statistical analyzed. The integument is formed by the keratinized squamous stratified epidermis supported by the dermis that is subdivided into the spongious layer with a loose arrangement, and the compact layer formed by collagenous fibers arranged compactly in a criss-crossed manner. Thick collagenous columns have a perpendicular trajectory, and are formed by the assembling of alternating collagenous lamellae in both animals. Short intercolumns of collagenous fibrils connecting collagenous lamellae obliquely or transversally are observed in R. catesbeiana dorsal integument. The present study provides evidences that B. ictericus and R. catesbeiana integument has well-organized compact dermis, constituted by collagenous lamellae in a plywood manner. The integument organization is in contrast to the literature in some aspects. This dermal arrangement is important to the biomechanical property of both anuran integuments.

Focusing properties of magnetic sectors of the wedge type. Part I

The focusing properties of inhomogeneous magnetic sector fields with cylindrical symmetry are investigated. For the case of symmetrical arrangement of object and image and perpendicular trajectories at the field boundaries expressions for the image aberrations up to the second order are given. It is shown that this special type of field has two-directional point to point focusing.

Focusing properties of magnetic sectors of the wedge type. Part II

The focusing properties of inhomogeneous magnetic sector fields with cylindrical symmetry, symmetrical arrangement of object and image and perpendicular trajectories at the field boundaries are investigated. First and second order aberrations are computed and compared with the analogous values of other stigmatic focusing magnets.