Entropy generation due to jet impingement on a surface: effect of annular nozzle outer angle

Abstract

PurposeThe purpose of this paper is to examine entropy generation rate in the flow field due jet emanating from an annular nozzle and impinging on to a flat plate. Since the flow field changes with the geometric configuration of the annular nozzle, the influence of nozzle outer cone angle on the entropy generation rate is considered.Design/methodology/approachThe steady flow field pertinent to jet impingement on to a flat plate is modeled with appropriate boundary conditions. A control volume approach is introduced to discretize the governing equations of flow and to simulate the physical situation numerically. Entropy generation rate due to heat transfer and fluid friction is formulated. The resulting entropy equations are solved numerically.FindingsThermodynamic irreversibility, which is quantified through entropy generation rate, gives insight into the thermodynamics losses in the flow system. Entropy generation rate is highly affected by the nozzle outer cone angle. In this case, increasing nozzle outer cone angle enhances the entropy generation rate, particularly due to fluid friction.Research limitations/implicationsThe predictions may be extended to include the nozzle area ratio and mass flow rate variation.Practical implicationsThe paper is a very useful source of physical information for improving nozzle design, particularly that which is used in a laser thick material cutting operation. It disseminates information for those working on both laser machining applications and entropy generation in flow systems.Originality/valueThis paper discusses the physical issues related to the entropy generation rate and offers practical help to an individual starting out on an academic career.