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An experimental study of the blowby past the apex seals and its controlling effect on the flow field was conducted in a motored rotary engine. A high speed flow visualization technique and laser Doppler anemometry (LDA) measurements were applied to analyze the blowby past two--piece and three-piece engine apex seals under motored conditions of 2000 rpm crank shaft speed. A light sheet from a 40 watt pulsed copper vapor laser was synchronized with a high speed rotating prism camera to record light scattered off microballoon particles onto motion picture films photographed at 5000 frames per second. A sequence of photographs is selected from the films to demonstrate the blowby characteristics past the apex seals and their effect on the flow field during the intake and compression strokes. Detailed LDA velocity measurements using propylene glycol as seeding particles, 0.6 μm in diameter, are also presented to quantify the blowby past the apex seals.

The purpose of this work was to develop a fiber optic imaging system for use in flow visualization studies at the Michigan State University Engine Research Laboratory. A flexible fiber optic image carrier was coupled with a high speed rotating prism camera to create a unique imaging system which can easily reach remote location test sites. The flow visualization study was conducted on a motored 3.5 L four-valve engine test rig. A 40 watt pulsed copper vapor laser was synchronized with the camera to produce motion picture film at 5000 frames per second (fps). The image carrier which is attached to the camera contained an 80 degree field of view (FOV) tip adapter for viewing the entire cross-sectional area of the cylinder. The area imaged was a radial plane located 3 cm from the intake valves. The engine rig was motored at 850 rpm with a flow rate of 18 kg/hr. Entrained microballoon seeding particles were filmed as they traveled through the cylinder.

Flow visualization observations are described in a motored stratified charge rotary engine. Analysis of the flow field is presented for naturally aspirated and supercharged conditions at shaft speeds of 675 and 1170 rpm, during the intake and compression strokes. The entrained air through the induction system is seeded by using microballoon particles (40 μm in mean diameter). Light scattered off the particles is recorded by high speed camera at 5000 frames per second. The camera is equipped with an optical pickup and pulse generator to trigger the 40 watt copper vapor laser synchronously with the rotating prism camera. Major flow features identified include leakage past the apex seal, separation at the rotor pocket and a large recirculation region during intake. Also, the motion pictures demonstrated that the rotor motion has the controlling effect on the turbulent flow field during the intake-compression strokes.