A Study on the Mechanism of In-Cylinder Tumble Generation by Directed Intake Ports

Liu, Ruilin; Chunrun, Zhang; Liang-qin, WU; An, Xiang-Bi; Yu, Yi-Kun; Shu-min, LI; Ma, Feng; Chen, Song

doi:10.4271/962089

Cited by 1 publication

(2 citation statements)

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“…The handle in Figure 3 is turned, the camshaft angle is adjusted from 40°to 140°, and then the lead screw is turned to adjust the phase difference u and set, respectively, to 0°, 4°, 8°, 12°, and 16°. The actual gas volume flow is measured by the flowmeter, and then the flow coefficient C F and the average flow coefficient C F are calculated according to formulas (5) and (6). A vane anemometer is mounted at the 1.75 times cylinder diameter below the axis of the cylinder head lower surface; it is used to measure the rotating speed of the vane, the speed value of the vane is sent to the computer, and then the swirl ratio N S is calculated according to formula (7).…”

Section: Test Methods and Test Proceduresmentioning

confidence: 99%

“…Gas motion during the gas exchanging process in four-valve gasoline engines is one of the main factors which affect the engine performance. 1,2 A number of ways of improving in-cylinder gas motion have been studied extensively, such as using a double injection strategy, 3 changing the structure geometries of the intake port, 4–6 changing the piston shape, 7 and so on. Normally, the double intake ports are symmetrically arranged in four-valve gasoline engines, and the profiles of two intake cams which drive the intake valves are almost consistent, so the lifts of two intake valves are the same in the intake process, and the gas velocity and flow of two intake valves are equal.…”

Section: Introductionmentioning

confidence: 99%

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Effects of the variable valve lift difference on in-cylinder gas flow in a four-valve gasoline engine

Zhang

Liu

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part D:

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The in-cylinder gas flow is an important factor that affects the engine performance. The appropriate swirl can reduce cycle-to-cycle variations, increase flame propagation speed, and improve the combustion efficiency. Many technologies can induce significant swirl, but lead to intake flow loss. In this research work, the variable valve lift difference adjustment mechanism is developed to obtain and adjust in-cylinder swirl without weakening flow capacity in a four-valve gasoline engine. The in-cylinder swirl and tumble characteristics generated by the variable valve lift difference adjustment mechanism are studied by means of experiment and simulation. The results of the experiment and simulation show the intensity of tumble and swirl under the larger lift valve is increased with the increase in the phase difference between two intake cams at same camshaft angle, and a large-scale swirl is formed in the cylinder when the camshaft angles change from 40° to 80°, and another large scale swirl is formed during the camshaft angles change from 100° to 140°, but the rotating direction of the secondary swirl is inverse to that of first swirl. The scale and shape of the in-cylinder tumble and swirl are not changed significantly with the increase in the phase difference between two intake cams when the camshaft angles change from 80° to 100°. A brief discussion on the research results that improve the performance of actual gasoline engine is given.

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Section: Test Methods and Test Proceduresmentioning

confidence: 99%