Numerical analysis of flow separation and side loads of a conical nozzle during staging

Abstract

The objective of this effort is to numerically investigate the effect of the fire-in-the-hole staging event on the start-up flow separation and side loads of a conical nozzle during flight. The axisymmetric transient flow structure in nozzle was examined by time-accurate numerical method with time-varying chamber pressure and separation gap width. Three-dimensional time-accurate computations to examine the side loads due to non-nominal staging movement were conducted for two particular cases: misalignment between two stages and the angle of the nozzle thrust vector direction. Each asymmetry case comprised several specific staging state points which determined the corresponding chamber pressure and staging gap width. As presented by the simulation results, the flow separation in nozzle is significantly prolonged and intensified by the obstruction of the lower stage dome. When the flow separation location moves close to the nozzle exit, a strenuously axial oscillation of the separation shock appears and lasts for a period of time. In the three-dimensional asymmetric computations, in spite of strenuous oscillation, the time-average of nozzle side loads indicate that the asymmetric staging situation could lead to large sustained lateral disturbance forces. An essential ingredient driving the flow unsteadiness and asymmetry is related to the deflected and reversed supersonic flow by the dome and interstage wall corner of lower stage.

Simulación numérica del flujo subexpandido en la tobera cónica experimental helios-x

“…El modelo de turbulencia de Menter [17] ha sido comparado con otros modelos de turbulencia para diferentes condiciones del flujo compresible con presencia de ondas de choque en diferentes equipos experimentales para flujo sobre-expandido y flujo sub-expandido, donde los resultados numéricos para dominios 2D de geometrías simétricas se superponen sobre los datos experimentales de presión en las paredes de equipos experimentales, en una tobera [18,19] y en un difusor transónico [20,21], siendo las formas de las ondas de choque de los resultados numéricos aproximadamente similares con las experimentales. Aplicaciones del modelo de turbulencia de Menter sustentan su valides para diferentes condiciones del régimen del flujo [22][23][24][25]. En dominios 3D, el aporte del análisis físico es mucho mayor, incluso para geometrías asimétricas, y cargas laterales asimétricas en el campo de flujo.…”

Evaluation of generalized k-ω turbulence model in strong separated flow estimation of thrust optimized parabolic nozzle

“…The simulation of shock wave-boundary layer interactions, especially in separated flows, is one of the most challenging topics that is often studied by compressible flow researchers. [11][12][13] Among the frequently reported issues is the inability of Reynolds-averaged Navier-Stokes (RANS)based turbulence models to accurately predict the onset of flow separation in TOP nozzles. Ostlund et al 14 evaluated four eddy viscosity turbulence models (EVMs) on the Vulcain nozzle.…”

Numerical analysis of the shock train evolution in planar nozzles with throat length

“…The study of compressible and viscous flow behavior for different geometries of supersonic nozzles applied to the aerospace area is recurrent [1][2][3]. The most prominent convergent-divergent supersonic nozzles are bell nozzles [1,[3][4][5], conical nozzles [1,[5][6][7][8][9] and planar nozzles [10][11][12][13]. For conical nozzles, the optimal range of the half angle, α, is between 12° and 18°.…”