Non-equilibrium Condensation Phenomenon Research Articles

CFD Investigation on Passive Control of Condensation Shock Wave. In Case of Steady Condensation Shock.

A rapid expansion of moist air or steam in a supersonic nozzle gives rise to nonequilibrium condensation phenomena. Thereby, the nozzle flow is affected by the latent heat released by condensation of water vapor. Many papers for the passive control of shock-boundary layer interaction using the porous wall with a plenum underneath have been reported on the application of the technique to transonic airfoil flows. In this paper, this passive technique is applied to a steady condensation shock wave generated in a supersonic nozzle. For the effect of the passive shock-boundary layer control on steady condensation shock, Navier-Stokes equations were solved numerically using a 3rd-order MUSCL type TVD finite-difference scheme with a second-order fractional-step for time integration. As a result, the state of flow field has been clarified.

Condensing nozzle flows: Ludwieg tube experiments and numerical/ theoretical modelling

AbstractThe present paper deals with homogeneously condensing flows of humid nitrogen in a Laval nozzle. The modelling of nonequilibrium condensation phenomena can be separated in two distinct processes: homogeneous nucleation and droplet growth. Our objective is to investigate the quality of a condensation model characterised by the following combination: the (corrected) Internally Consistent Classical Theory for the nucleation process and a generalised transitional growth model, with the droplet temperature calculated explicitly via the wet‐bulb equation. Our theoretical predictions have been then compared with our experimental results on droplet sizing showing a good agreement.

Passive control of unsteady condensation shock wave

A rapid expansion of moist air or steam in a supersonic nozzle gives rise to nonequilibrium condensation phenomena. Thereby, if the heat released by condensation of water vapour exceeds a certain quantity, the flow will become unstable and periodic flow oscillations of the unsteady condensation shock wave will occur. For the passive control of shock-boundary layer interaction using the porous wall with a plenum underneath, many papers have been presented on the application of the technique to transonic airfoil flows. In this paper, the passive technique is applied to three types of oscillations of the unsteady condensation shock wave generated in a supersonic nozzle in order to suppress the unsteady behavior. As a result, the effects of number of slits and length of cavity on the aspect of flow field have been clarified numerically using a 3rd-order MUSCL type TVD finite-difference scheme with a second-order fractional-step for time integration.

Studies of Condensation Shock Waves : Part 1, Mechanism of their Formation

An expansion of moist air or steam in a supersonic nozzle gives rise to nonequilibrium condensation phenomenon, and a condensation shock wave appears in the supersonic section of the nozzle. In the present paper, a condensation shock wave was observed optically by a method in the case of moist air expanding in a supersonic nozzle, and the effect of the relative humidity of moist air on the shape of a condensation shock wave was discussed. Furthermore, a flow of moist air expanding in a supersonic nozzle was analyzed by the method of characteristics. Based on these experimental and calculated results, the mechanism of formation of a condensation shock wave was clarified.