Confined jet thrust vector control nozzle studies

Abstract

Axial and vectored flow behavior of an axisymmetric confined jet thrust vector control (CJTVC) nozzle is studied experimentally under steady-state and dynamic conditions. Pressurized secondary air injection is used to vector the nozzle at various levels of primary (chamber) air pressure. Attention is focused on internal flow characterization, nozzle instability, and the influence of secondary mass flow rate on vectored side force. The overexpanded flow separation point is located during axial test runs and compared to empirical predictions. Side force and mass flow rate measurements suggest that choked secondary mass flow occurs prior to the secondary mass flow rate that generates a maximum side force. Cavity pressure oscillations and nozzle side force response times are investigated to further characterize the dynamic behavior of the CJTVC nozzle. Nomenclature A = area a = cavity acoustic speed D = throat diameter d = cavity diameter F = force / = eigenfrequencies L = nozzle length from throat to exit M = Mach number m = mass flow rate P = stagnation pressure p = static pressure St = cavity Strouhal number, /Trd/a x = axial distance from throat a = conical half-angle y = ratio of specific heats Subscripts a = axial b = cavity downstream of separation e = exit m = circle nodal parameter n = radial nodal parameter p = primary s = side/separation/secondary w = wall