On Discharge Capability and Swirl Generation Capability of Swirler
Fuel-air mixing process is one crucial key to determine the performance of a diesel engine, and it is crucially determined by swirl within cylinder. For generating strong swirl within the cylinder, a new device named swirler has been propounded. In the present paper, four swirlers have been employed to experimentally study the performance on both the discharge capability and swirl generation capability. The steady flow test bench was employed to study the both capabilities in macro-level. Then, a water-flow model was employed to observe the flow motion within the cylinder via the tested swirlers. The results indicate that adopting swirler with a suitable configuration could generate strong swirl without remarkable discharge capability loss.
An experimental investigation of pneumatic swirl flow induced by a three lobed helical pipe
This paper presents a discussion of the results and conclusions drawn from a series of experiments conducted to investigate the swirl flow that are generated by a three lobed helical pipe mounted within a laboratory scale pneumatic conveying rig. The experiments employed Laser Doppler Anemometry (LDA) to quantify the strength of the induced vortex formations and the decay rates of the observed downstream swirl flows over a range of Reynolds number in the turbulent regime. Instantaneous point velocity measurements were resolved in three directions across regular measurement grids transcribed across parallel planes located at four distances downstream of the swirl inducing pipe section. The equivalent axial, radial and tangential velocities were subsequently computed at these grids points. The degree of swirl measured across each measurement plane was expressed in terms of a defined swirl number. It was concluded that the three lobed helical pipe gave rise to a wall jet type of swirl whose rate of observed downstream decay is related to the Reynolds number of the upstream flow and the distance downstream of the swirl pipe. The decay rates for the swirl flows were found to be inversely proportional to the Reynolds number of the upstream flow. The swirl pipe was observed to create a redistribution of the downstream velocity field from axial to tangential, accompanied by a transfer of axial to angular momentum. The findings of this paper are believed to improve understanding to assist the selective use of swirl flow within lean phase particles pneumatic transport systems.
Mass transfer to local electrodes at wall and wall friction factor in decaying turbulent swirl flow
Abstract This paper describes an investigation of mass transfer to local electrodes at the wall and wall friction factor behaviour in decaying swirl flow in a circular duct generated by short helical swirl generators. Five swirl generators with angles between 15–70° to duct axis were employed. The experiments were carried out in a Reynolds number range 8900-27 000 and at a Schmidt number of 1692. The axial distribution of the mass transfer to a circular electrode at the wall were measured using an electrochemical technique and the friction factors at the wall were calculated. Flow visualization experiments showed that no circulation nor dead zone occurs in the system. The local mass transfer data were correlated in the form of Shx = 0.0490 Rex0.817 (1+tan θ0)0.508, Sc 1 3 , for the whole range of swirl generator angles and the following correlations were developed f = 0.2517 Rex−0.263 (1 + tan θ0)0.880 and f = 39.810 Rex−0.642 (1 + tan θ0)0.746 for local friction factor for swirlers of 15–45° and 60 and 70°, respectively.