Gas Velocity Measurements of a Motored and Firing Engine by Laser Anemometry

Asanuma, Tsuyoshi; Obokata, Tomio

doi:10.4271/790096

Cited by 30 publications

(4 citation statements)

References 2 publications

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“…Only a few firing results were presented, but these serve to show that the major differences from the motored case are confined to the region after combustion. A similar conclusion was reached by Asanuma & Obokata (1979), who found a much stronger reverse squish after top-dead-centre in the firing case. Cole & Sword's (1978) data show a steady narrowing of the velocity spectra throughout the compression stroke as the inlet-generated turbulence decreases in magnitude, the relaxation of the flow continuing well into the expansion stroke.…”

supporting

confidence: 81%

“…Optical access to the cylinder was provided by a small window located in the head and, unlike that for the above measurements, was restricted. In addition, the laser Doppler anemometer had to be operated with back-scattered light, with consequent increase in instrumentation complexity and decrease in measurement precision.A summary of previous investigations of in-cylinder flow in real engines is provided in table 1; with the exceptions of Asanuma & Obokata (1979) an (i Renshaw & Wigley (1979), these made use of back-scattered light. In general, these in vestigations have been concerned with development of instrumentation and, apart from Rask (1979), few useful data have been provided.Rask's (1979) measurements, in a side-valved Onan research engine, reveal the strong vortical nature of the flow field, the apparent centre of rotation moving rapidly around the cylinder with opposite motions on the intake and compression strokes.…”

mentioning

confidence: 99%

“…A summary of previous investigations of in-cylinder flow in real engines is provided in table 1; with the exceptions of Asanuma & Obokata (1979) an (i Renshaw & Wigley (1979), these made use of back-scattered light. In general, these in vestigations have been concerned with development of instrumentation and, apart from Rask (1979), few useful data have been provided.…”

mentioning

confidence: 99%

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Measurements of the in-cylinder flow of a motored four-stroke reciprocating engine

Morse

Whitelaw

1981

Proc. R. Soc. Lond. A

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Measurements of the mean and r. m. s. components of the swirl velocity have been obtained over the intake and compression strokes of a single-cylinder, four-stroke, diesel engine motored, with and without compression, at rotational speeds between 325 rev/min and 675 rev/min. During the intake stroke, the mean-velocity values show only a small dependence on whether compression is applied - the levels of r. m. s. velocity are however noticeably lower under compressing conditions. The swirl profiles are characterized by a region of high velocity near the cylinder wall, corresponding to the strong jet-action induced by the masked-valve arrangement, with additional peaks in the profiles, indicative of the inward spiralling motion of the flow. By bottom-dead-centre, the peaks are no longer in evidence and the swirl tends towards solid-body rotation in the central regions of the cylinder. After the intake valve closes ( θ = 215°), the apparent centre of rotation shows an abrupt displacement in the direction of the valves and, under compressing conditions, the centre of rotation gradually returns towards the cylinder axis, although pure solid-body rotation about this point is not achieved until the piston reaches top-dead-centre. The swirl velocities show a steady decrease until θ ≈ 300°, when the effect of the flow being forced into the combustion bowl gives rise to increasing velocities. Without compression, the flow accelerates near the cylinder axis past mid-stroke, but the swirl velocities decrease rapidly as the piston approaches top-dead-centre and air escapes through the exhaust valve.

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confidence: 99%

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Measurements of the in-cylinder flow of a motored four-stroke reciprocating engine

Morse

Whitelaw

1981

Proc. R. Soc. Lond. A

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“…Asanuma and Obokata (1979) compared LDV measurements obtained during motored and fired operation of a side-valved L-head engine having strong squish. First, because the intake valve typically opens before the exhaust stroke is complete, hot exhaust gases temporarily flow into the intake port, raising wall temperatures in this region.…”

Section: Introductionmentioning

confidence: 99%