Search Results

This study involves the development of high speed flow visualization and laser doppler velocimetry (LDV) systems which are used to study the fuel spray-air mixing flow characteristics within the combustion chamber of a motored rotary engine. A 40-watt copper vapor laser is used as the light source. Its beam is focused down to a sheet approximately 1 mm thick. The light plane is passed through the combustion chamber, which allows complete optical access, and it illuminates smoke particles which were entrained in the intake air. The light scattered off the particles is recorded by a high speed rotating prism camera. Movies are made showing the air flow within the combustion chamber. The results of a movie showing the development of a high speed (100 Hz) high pressure (68.94 MPa, 10000 psi) fuel jet are also discussed. The visualization system is synchronized so that a pulse generated by the camera triggers the laser's thyratron.

The purpose of this work was to develop a high speed flow visualization system which could be used to observe the behavior of the air flow in a steady flow cylinder head assembly. This type of experimental rig has been used by engineers for many years to evaluate valve discharge coefficients. This study is believed to be the first high speed flow visualization of the air flow in a system of this type. Particular emphasis was placed on the characterization of intake generated swirl and tumble motions within the cylinder. A 40 watt copper vapor laser was used to expose motion picture films at 5000 frames per second. The light scattering medium was phenolic microballoons. Based on the flow visualization results, selected LDV measurements were made to quantify the visual observations. A propylene glycol aerosol was used for seeding in the LDV experiments.

A high speed flow visualization technique was utilized to study fuel spray development and the fuel-air mixing process in a direct fuel injection motored rotary engine assembly. Kerosene fuel was injected through a single hole nozzle at an angle of 60° from the horizontal axis into the combustion chamber. The nozzle was installed in a Servojet fuel injection system that was mounted in the central housing of a rotary engine. A 40 watt copper vapor laser was sychronized with a high speed rotating prism camera to expose motion picture films at 5000 frames per second (fps). The fuel spray structure was studied at injection pressures of 44 and 70 MPa, and at nominal injection durations of 1.2 and 2.8 ms. The engine shaft speed was 2000 rpm. A sequence of successive frames was selected from high speed films and then used to analyze the fuel spray characteristics. The flow field and rotor motion which had contributing effects on the fuel spray behavior were also considered.

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.

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.

Laser Doppler velocimetry (LDV) has been used to make ensemble averaged and root mean square (RMS) velocity measurements at a crank shaft speed of 675 rpm in a motored rotary engine assembly. Sapphire windows on both ends of the side housings allowed forward scatter optical access. Measurements were taken during the intake and compression strokes. Also, measurements were made in the major plane (defined by the major axis and the normal to the side housing) near the central housing wall to quantify the blowby that has proven to be a dominating feature in the intake flow pattern. This phenomenon has not been previously reported in the literature and has a major impact on how the Rotary Combustion Engine (RCE) combustion process can be numerically simulated. The intake stroke flow pattern was found to be dominated by a large scale vortical structure circulating in the opposite direction from the rotor motion.

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.