The Effect of Manifold Cross-Flow on the Discharge Coefficient of Sharp-Edged Orifices

The objective of this study is to determine the effect of manifold cross-flow on the discharge coefficient and cavitation characteristics of sharp-edged orifices over a wide range of flow-rates, back-pressures and cross-flow velocities. The orifice geometries studied cover a range of orifice diameters, length to diameter ratios and orifice angles characteristic of impinging element liquid rocket injectors. Experimental results for an orifice angle of 900 with respect to the manifold are presented here. Along with the experimental effort, an analytical model is being developed. The model predicts the discharge coefficient for a sharp edged orifice over a wide range of flow regimes including cavitating and non-cavitating flow, and for a wide range of orifice geometries. The analytical model generally shows good agreement with the experimental data over the range of conditions studied here. The model also closely follows the experimental data for cavitating flow except when the orifice length to diameter ratio is small, in which case the model over-predicts the discharge coefficient.