EFFECTS OF RELATIVE MASS FLUX OVER THE RECESSED PART OF THE NOZZLE ON THE DISCHARGE COEFFICIENT

To evaluate the effi ciency (perfection) of the processes of discharge from a recessed nozzle of a solid rocket motor (solid-propellant rocket engine), the parameter of relative mass fl ux has been introduced instead of the mass fl ow ratio. Advanced methods of computational fl uid dynamics have been used to conduct investigations into the effects of relative mass fl ux over the recessed part of the inlet portion of the nozzle on the discharge coeffi cient. Consideration has been given to versions of the nozzle inlet portion of ellipsoid shape and of a shape constructed using the Vitoshinsky formula. The effects of relative mass fl ux on the nozzle metering characteristics have been determined with account for the changes in the geometric parameters of its recessed part and for the recess depth. A comparison is presented of the obtained results with the results of earlier investigations into radius-shaped nozzle inlet portions. Additionally, investigations have been conducted into the effects of the gas infl ow from the surface of the charge over the recessed part of the nozzle at constant geometry of its ellipsoid- or radius-shaped inlet portion on the nozzle discharge coeffi cient at different recess depths. Basic recommendations have been formulated for designing inlet portions of recessed nozzles.
To evaluate the effi ciency (perfection) of the processes of discharge from a recessed nozzle of a solid rocket motor (solid-propellant rocket engine), the parameter of relative mass fl ux has been introduced instead of the mass fl ow ratio. Advanced methods of computational fl uid dynamics have been used to conduct investigations into the effects of relative mass fl ux over the recessed part of the inlet portion of the nozzle on the discharge coeffi cient. Consideration has been given to versions of the nozzle inlet portion of ellipsoid shape and of a shape constructed using the Vitoshinsky formula. The effects of relative mass fl ux on the nozzle metering characteristics have been determined with account for the changes in the geometric parameters of its recessed part and for the recess depth. A comparison is presented of the obtained results with the results of earlier investigations into radius-shaped nozzle inlet portions. Additionally, investigations have been conducted into the effects of the gas infl ow from the surface of the charge over the recessed part of the nozzle at constant geometry of its ellipsoid- or radius-shaped inlet portion on the nozzle discharge coeffi cient at different recess depths. Basic recommendations have been formulated for designing inlet portions of recessed nozzles.
Author:  A. N. Sabirzyanov, A. N. Kirillova
Keywords:  solid rocket motor, recessed nozzle, discharge coeffi cient, mass fl ux, computational fl uid dynamics
Page:  670-676