High resolution DPIV measurements are made of a vortex ring formed by a piston/cylinder mechanism ~Reynolds number 3700 and 7500!. A complex ring structure is identified. The stopping condition of the piston leads to vortical fluid collecting near the forward stagnation point of the ring. In addition, the roll-up of the core produces a vorticity distribution that departs from a simple Gaussian ...

Environmentally speaking, of assorted widely-used refrigeration systems, the trans-critical CO2 system is one of the potential competitors. In this research, a horizontal semi-hermetic rolling piston compressor is developed for trans-critical CO2 cycle. This paper also presents a series of mathematical simulation models to identify the main factors influencing compressor’s performance. Based up...

An experimental study has been conducted to provide insight into heat transfer to the piston of a light-duty single-cylinder research engine under Conventional Diesel (CDC), Homogeneous Charge Compression Ignition (HCCI), and Reactivity Controlled Compression Ignition (RCCI) combustion regimes. Two fast-response surface thermocouples embedded in the piston top measured transient temperature. A ...

We study numerically and theoretically (on a heuristic level) the time evolution of a gas confined to a cube of size L divided into two parts by a piston with mass ML ’ L which can only move in the x-direction. Starting with a uniform ‘‘double-peaked’’ (non Maxwellian) distribution of the gas and a stationary piston, we find that (a) after an initial quiescent period the system becomes unstable...

OBJECTIVES/HYPOTHESIS To evaluate the long-term (5-year) results of the shape-memory nitinol stapes piston in the surgical treatment of otosclerosis. STUDY DESIGN Retrospective case review in a tertiary referral center. METHODS The patients were adults with clinically proven otosclerosis undergoing stapedotomy. Stapedotomy and ossicular chain reconstruction using a shape-memory nitinol stap...

The controversial problem of the evolution of an isolated system with an internal adiabatic wall is investigated with the use of a simple microscopic model and the Boltzmann equation. In the case of two infinite volume onedimensional ideal fluids separated by a piston whose mass is equal to the mass of the fluid particles we obtain a rigorous explicit stationary non-equilibrium solution of the ...

Our goal is to model and analyze a stationary fluid flow through the junction of two pipes in the gravity field. Inside ’vertical’ pipe there is a heavy piston which can freely move along the pipe. We are interested in the equilibrium position of the piston in dependence on geometry of junction. Fluid is modeled with the Navier-Stokes equations and the piston is modeled as a rigid body. We form...

cylinder tumble flows of a single cylinder two-valve engine under motoring conditions with two pentroof pistons having different cavities at an engine speed of 1000 rev/min., during suction and compression strokes using particle image velocimetry (PIV). The two-dimensional velocity vector fields are analyzed on a vertical plane passing through the axis of the cylinder. To quantify the tumble fl...