Suppose that q is a prime power exceeding five. For every integer N there exists a 3-connected GF(q)-representable matroid, in particular, a free spike or a free swirl, that has at least N inequivalent GF(q)-representations. In contrast to this, Geelen, Oxley, Vertigan and Whittle have conjectured that, for any integer r > 2, there exists an integer n(q, r) such that if M is a 3-connected GF(q)...

We study the growth of disturbances to vortex rings with swirl, which are exact solutions of the Euler equations of inviscid ow, using two contrasting methods. The motion of the perturbed vortex rings can be regarded as a prototype for the inviscid dynamics of vortex structures in 3D. Exact rings with swirl are computed as steady, axisymmetric ows using a variational method. Asymptotic analysis...

A contra-rotating marine current turbine has a number of attractive features: near-zero reactive torque on the support structure, near-zero swirl in the wake, and high relative interrotor rotational speeds. Modified blade element modelling theory has been used to design and predict the characteristics of such a turbine, and a model turbine and test rig have been constructed. Tests in a towing t...

Different CFD models of reverse-flow centrifugal separators namely swirl tubes have been built in order to study and detail analysis of the phenomenon of the "end of the vortex". The present work based on previous experience and experimental activities in the field of this phenomenon. The models was built in absolutely agree with geometrical characteristics and operating conditions of experimen...

The whistling induced by a low-Mach turbulent flow through deep axisymmetric cavity in duct is investigated theoretically and experimentally. experiments include acoustic measurements stereoscopic particle image velocimetry (PIV). paper focuses on the effect of mean swirl dynamics azimuthal aeroacoustic modes. has two origins: one component imposed controlled tangential air injection upstream c...

The structure of the pressure swirl nozzle is key factor affecting atomization quality. Optimal design conducive to improving quality and has important significance for efficiency stability combustor. effect section diameter, contraction angle, straight expansion angle on spray cone liquid film thickness studied by numerical simulation. results show that both decrease with increase angle. As di...

PCCI engines can reduce NOx and PM emissions simultaneously without sacrificing thermal efficiency, but a low combustion temperature resulting from early fuel injection, and ignition occurring prior to TDC, can cause higher THC and CO emissions and fuel consumption. In conclusion, it was found that the PCCI combustion achieved by the 2-stage injection strategy with optimized calibration factors...

Swirling flows are related to the spiral motion in the tangential direction in addition to the axial and radial direction using several swirl generators. These type of flows are used in combustion chambers to improve flame stability, heat exchanger to enhance heat transfer coefficients, agricultural spraying machines and some vertical pipes to move slurries or transport of materials. However, o...