In this paper, hydroforming process of bent tubes in T-shaped die is studied for pulsating and linear pressure paths by the finite element method. Forming Limit Diagrams (FLDs) and thickness distribution curves are used to investigate the effect of pulsating pressure on hydroforming process. In addition, the obtained numerical results are compared with experimental results of hydroforming of st...

In this paper, the mechanism of improvement of formability in pulsating hydroforming of T-shape tubes is investigated by the finite element simulation and experiment. It is shown that local thinning was prevented by oscillating the internal pressure, because the protrusion is formed gradually by the prevention of sharp bulging. In the hydroforming, for the pulsating pressure, several steps occu...

in recent years, the hydroforming due to reduction in weight and increase in strength of automotive parts has attracted attention of the automotive industry. thus, the knowledge of the process to produce parts with desired quality and accuracy has been growing. one of the effective methods in improving the formability in the hydroforming is known as pulsating hydroforming. however, the reason o...

In this study, two-dimensional pulsating unsteady flow of nanofluid through a rectangular channel with isothermal walls is investigated numerically. The set of resultant algebraic equations is solved simultaneously using SIMPLE algorithm to obtain the velocity and pressure distribution within the channel. The effects of several parameters, such as volume fraction of different nanoparticles, Rey...

A pulsating laminar flow of a viscous, incompressible liquid in a rectangular duct has been studied. The motion is induced under an imposed pulsating pressure difference. The problem is solved numerically. Different flow regimes are characterized by a non-dimensional parameter based on the frequency (v) of the imposed pressure gradient oscillations and the width of the duct (h). This, in fact, ...

Separating oscillating and pulsating flows in an internal adverse pressure gradient geometry are studied experimentally. Time-resolved PIV measurements and simultaneous pressure measurements reveal that, in oscillating flow, during the accelerating portion of the cycle, the flow remains attached in spite of a very large adverse pressure gradient. During the decelerating portion of the cycle, th...

A current-voltage characteristic of direct current (DC) gas discharge operated in a micro gas jet injected into a secondary electron microscope (SEM) chamber is presented. Ar gas was injected through a 30 μm orifice gas nozzle (OGN) and was evacuated by an additional pump to keep the high vacuum environment. Gas discharges were ignited between the OGN as anode and a counter electrode of Si wafe...

In the present paper, a numerical method has been demonstrated which works on an overall NewtonRaphson type algorithm and is capable of solving the “inverse” problem for turbulent, fullydeveloped, pulsating pipe flows, where the mass flow rate, rather than the pressure gradient is prescribed as a periodic function of time. The momentum equation, governing the transient, fullydeveloped pulsating...

Pulsating and explosive time profiles of mm-wave solar bursts observed at Metsähovi are examined in terms of the energy release in a single current-carrying loop. We suppose that the electric current in the loop is driven by photospheric convective flows. The flare occurs due to flute instability provoking the penetration of partially ionized plasma from the chromosphere or prominence into the ...

An adaptive Helmholtz resonator was designed and adapted to hydraulics. The resonator was controlled by openand closed-loop controls so that 20 dB attenuation of the peak-to-peak value of the pulsating pressure was maintained. The closed-loop control was noted to be better, albeit it was slower because of its low pressure and temperature variation, which caused variation in the effective bulk m...