In this paper we prove existence, uniqueness and regularity of certain perturbed (subsonic–supersonic) transonic potential flows in a two-dimensional Riemannian manifold with “convergent–divergent” metric, which is an approximate model of the de Laval nozzle in aerodynamics. The result indicates that transonic flows obtained by quasi-one-dimensional flow model in fluid dynamics are stable with ...

Cavitation and turbulence inside a diesel injector play a critical role in primary spray breakup and development processes. The study of cavitation in realistic injectors is challenging, both theoretically and experimentally, since the associated two-phase flow field is turbulent and highly complex, characterized by large pressure gradients and small orifice geometries. We report herein a compu...

Starting flow through a nozzle or orifice typically results in the transient formation of a leading vortex ring and trailing jet. Experiments are conducted to investigate the dynamics of this process in the case of a temporally variable nozzle exit diameter, with the aim of understanding these flows as they occur in Nature and emerging technologies. By kinematically decoupling the source flow f...

Particle beams have traditionally been produced by supersonic expansion of aparticle-ladengas through a single nozzle to vacuum. However, it has been shown that, by passing the particle-laden gas through a series of axi-symmetric subsonic contractions and expansions (an aerodynamic lens system) prior to the supersonic expansion to vacuum through a single nozzle, beam divergence can be signiŽ ca...

The discharge of grains from a hopper or silo has received considerable attention, both because it is relevant to numerous industries, and a model system for examining general features of granular flow [1, 2]. These studies have generally focused on the motion of grains inside the hopper and the flow rate of material out of the nozzle. It is known that these systems can exhibit intermittent jam...

The geometry of the diesel fuel injection nozzle and fuel flow characteristics in the nozzle significantly affects the processes of fuel atomization, combustion and formation of pollutant emissions in diesel engine. To improve the process of fuel injection, CFD packages are used. Since CPU times are often high, partial models are used for the analysis. In presented paper the influence of differ...

Lateral nozzle forces are known to cause severe structural damage to any new rocket engine in development during test. While three-dimensional, transient, turbulent, chemically reacting computational fluid dynamics methodology has been demonstrated to capture major side load physics with rigid nozzles, hot-fire tests often show nozzle structure deformation during major side load events, leading...

Numerical studies have been carried out using a validated two-dimensional standard k-omega turbulence model for the design optimization of a thrust vector control system using shock induced self-impinging supersonic secondary double jet. Parametric analytical studies have been carried out at different secondary injection locations to identifying the highest unsymmetrical distribution of the mai...

BACKGROUND AND OBJECTIVES Cryogen spray cooling (CSC) is used for epidermal protection during laser dermatologic surgery. However, further research is necessary to optimize the use of CSC for many applications, particularly in patients with darker skin types, and in procedures with deep-targeted chromophores. STUDY DESIGN/MATERIALS AND METHODS With the objective to enhance cryogen spray atomi...