Analysis of of Injection-Velocity Effects on Rocket Motor Dynamics and Stability

A concept of combustion time lag that includes dependency on injection velocity is introduced. The concept is used in the formulation of chamber transfer functions and in an analysis of low-frequency combustion instability. Theoretical frequency responses and stability boundaries are compared with those obtained when the injection-velocity effect on the time lag to be an important consideration, in the theory of chamber dynamics and combustion instabilit

Experimental Investigation of Dynamic Relations in a 48-inch Ram-jet Engine

Engine dynamics were investigated for supercritical operation of the ram jet at Mach 2.75 over a range of simulated altitudes from 68,000 to 82,000 feet. Indicial-and frequency-response tests were conducted with fuel flow as the input variable. For a wide range of operating points, the response of static or total pressure to fuel flow consisted of a dead time followed by a response form that generally approximated a linear, first-order, lead-lag. The dead time varied significantly only with distance from the combustion zone. The rise ratio and the time constant of the lead-lag function were nearly independent of the pressure sensed

NACA Research Memorandums

Memorandum presenting an analysis to determine, for control design purposes, the approximate response of pressures in the ramjet engine to changes in fuel flow. In the first part, the response after dead time is treated by the linearized lumped-parameter method. In the second, the dead time occurring between the change in fuel flow and the beginning of the pressure response is discussed

NACA Technical Notes

From Summary: "The effect of small downstream pressure distributions on the position of a normal shock in a duct with area variation is analyzed. For the analysis, the gas flow is treated as quasi-one-dimensional, and boundary layer is neglected. The analysis shows that there is a first-order lag relation between shock position and small downstream disturbances in pressure which occur at frequencies below a given limit.

NACA Research Memorandums

Engine dynamics were investigated for supercritical operation of the ram jet at Mach 2.75 over a range of simulated altitudes from 68,000 to 82,000 feet. Indicial-and frequency-response tests were conducted with fuel flow as the input variable. For a wide range of operating points, the response of static or total pressure to fuel flow consisted of a dead time followed by a response form that generally approximated a linear, first-order, lead-lag. The dead time varied significantly only with distance from the combustion zone. The rise ratio and the time constant of the lead-lag function were nearly independent of the pressure sensed