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Tubular jet generation by pressure pulse impact

Morsink, Gerben (2011) Tubular jet generation by pressure pulse impact.

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Abstract:The formation of highly focused thin jets caused by impact of a pressure pulse on a free surface is studied experimentally. Jets with a tip speed up to 50ms−1 are measured. The pressure pulses generated by an eddy-current actuator have a duration of about 100 μs and reach a peak amplitude of over 100 bar. The pressure pulses travel upwards through an ultrapure water column in a rigid steel tube of 1m length at approximately the speed of sound. The pressure is measured using two pressure sensors working at 20MHz. A glass tube of 2mm to 4mm in radius is inserted at the top of the steel tube, to enable visualisation of the free surface and the jet formation following the impact of the pressure pulse. These images are analysed to study the effect of the experimental parameters on the jet velocity of the jet tip: amplitude of the pressure pulse, initial curvature, and tube diameter1. The amplitude of the pressure pulse is shown to have a linear relation with the velocity of the jet tip. The initial curvature of the free surface, or meniscus, ranged from highly concave to slightly convex and is shown to be an important aspect in the formation of the jet, which can be described by one parameter: the contact angle (θc). It is shown that the tip speed is proportional to cos (θc). A combination of linear acoustic theory with the contact angle dependency leads to good agreement with the measurements. It is shown that the speed of the tip of the jet does not depend on the tube radius.
Item Type:Essay (Master)
Faculty:TNW: Science and Technology
Subject:33 physics
Programme:Applied Physics MSc (60436)
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