Role of Ambient Pressure on Colliding Jets

TL;DR

This study investigates how ambient pressure influences the merging or bouncing behavior of colliding jets, revealing a non-monotonic pressure effect and new collision regimes at different pressures.

Contribution

It demonstrates the existence of a critical pressure threshold affecting collision outcomes, extending understanding beyond atmospheric conditions.

Findings

Collision outcome transitions with impact velocity.

Existence of a critical pressure below which bouncing is promoted.

Non-monotonic influence of pressure on jet collision behavior.

Abstract

In this letter, the merging-vs-bouncing response of obliquely-oriented colliding jets under elevated and reduced gaseous environment pressures was experimentally examined. Experiments with water and n-tetradecane confirmed that the collision outcome transitions from merging to bouncing, and then to merging again, when the impact velocity was increased. This behavior which was previously reported for atmospheric pressure, has now also been observed at elevated and reduced pressures. New results also show that there exists a critical pressure (0.9 bar for tetradecane and 5 bar for water) below which increasing pressure promotes bouncing (expands the bouncing regime), while beyond this, merging is promoted (reduces the bouncing regime) instead. This leads to a non-monotonic influence of pressure on the non-coalescence outcomes of collisional jets, which was not previously reported. The study provides evidence of new behaviors in colliding jets at reduced and elevated pressures, which differs from well-studied droplet-droplet collisions.