Toshiyuki Hasegawa

Study on the DI Diesel Sprays Injected by the Variable Orifice Nozzle (VON)

A Variable Orifice Nozzle (VON) by changing a cross-sectional area of the nozzle injection hole, for improving a rate of injection and injection duration, has been developed to study its spray characteristics. Injection and spray pattern responded to the nozzle orifice cross-sectional area which is changing larger to smaller. Transient behavior of the sprays was recorded by two-frame CCD camera system which is based on a microscope with a long working distance. The analysis of the diesel spray velocity vectors were conducted using PIV analyzer with cross-correlation method. The system has been used with various techniques to provide a powerful tool for spray analysis.

Visualization of Diesel Sprays Injected from a Variable Orifice Nozzle

Transient diesel spray which was visualized by shadow photography was observed immediately at near a injection hole exit of a Variable Orifice Nozzle, by exchanging a injection hole diameter. Transient behavior of the spray at the onset of injection was recorded by means of the rotary mirror type high speed framing camera with frame rates up to 700000 frames/sec. The analysis of this spray velocity was conducted using Particle Image Velocimetry (PIV). A rapid time series of photographs on 35mm film which were taken by the camera, were translated to the computer by a film scanner to convert to a digital image. And then velocity were obtained by cross-correlation PIV technique. With this technique, two demensional spatial cross-correlations of the extinction light intensities were taken between a pair of picture images. The result shows that, velocity vector maps are good agreement with spray photographs. Velocity vectors on early mixing region of diesel spray near nozzle hole exit was drop to as little as 0.5% of the spray tip velocity.