Abstract We propose a new kind of compound optical vortex (COV) generator in this paper. The device consists an inner spiral phase plate (SPP) and outer annular plate. There is opaque band between two SPPs. Under the flat-top beam irradiation, concentric multi-ring COV rings with different topological charges radial radii can be generated. theoretical analysis lays foundation for design generat...

In air-cooling applications with frost production, heat exchanger performance is often air-side limited, because the two-phase flow of the refrigerant provides excellent heat transfer coefficients, and because designers typically use a large air-side fin spacing for frost tolerance. The large fin spacing prolongs operation of the heat exchanger by mitigating the effect of the accumulating frost...

In this paper, the implicitly implemented LES method and fifth order bandwidth-optimized WENO scheme are used to make comprehensive studies on the separation topology of the MVG controlled flow at M=2.5 and Re θ θ θ θ =5760. Experiments are also made to verify the prediction of the computation. Analyses are conducted on three categories of the topology: the surface separation, cross-section sep...

Leading edge noise is a significant broadband noise source in aircraft engines, and is the primary broadband noise mechanism in outlet guide vane noise in turbofans, and broadband rotor wake interaction noise in contra-rotating open rotor engines. Previous authors have studied the effects of various aspects relating to this noise source, including airfoil geometry effects, cascade effects, and ...

Dynamics and chemistry of vortex remnants in late Arctic spring 1997 and 2000: Simulations with the Chemical Lagrangian Model of the Stratosphere (CLaMS) P. Konopka, J.-U. Grooß, S. Bausch, R. Müller, D. S. McKenna, O. Morgenstern, and Y. Orsolini Institute for Stratospheric Chemistry (ICG-I), 52425 Jülich, Germany National Center for Atmospheric Research, Boulder, CO, USA Max Planck Institut f...

To discover the nonlinear characteristics of pipe flow, we simulated the flow as a sum of many vortex rings. As a first step, we investigated the nonlinear interaction among a maximum of three vortex rings. The pipe wall was replaced by many bound vortices. A free vortex ring moves right or left according to the radius, and that of a particular radius keeps the initial position. The energy of a...

One of the solutions of the Helmholtz equation is the vortex beams. In the recent decades, production and applications of these types of beams have found serious attentions. Determination of the vortex beam topological charge and its sign are very important issues. Odd number of reflections of the vortex beam changes its vorticity. In this paper, we have used a q-plate to generate a vortex beam...