Preliminary Report of Experimental Investigation of Ram-Jet Controls and Engine Dynamics Page: 2 of 71
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TECH LIBRARY KAFB, NM
0144000
NACA RM E54HOl
NATIONAL ADVISORY COMMITTEE FOR AERONAUTICS
RESEARCH MEMORANDUM
PREL2MIARY REPORT OF EXPERIMENTAL INVESTIGATION OF
RAM-JET CONTROLS AND ENGINE DYNAMICS
By G. Vasu, F. A. Wilcox, and S. C. Himmel
SUMMARY
The preliminary results of an experimental investigation of the in-
r ternal dynamics of a ram-jet engine and the steady-state and dynamic
performance characteristics of a number of ram-jet engine controls are
presented. The investigation was conducted on a 16-inch ram-jet engine
over the range of free-stream Mach numbers from 1.5 to 2.16.
Three types of engine control system were investigated. These were
(1) shock positioning, (2) direct control of diffuser-exit pressure, and
* (3) an optimalizing control designed to obtain peak pressure recovery
from the diffuser. All three systems operated satisfactorily and appear
to present practicable means of controlling ram-jet engines.
The responses of pressures within the ram-jet engine to disturbances
in fuel flow appear to comprise 'a dead time in cascade with a lead-lag
characteristic. The dead time varied from 0.02 to 0.05 second over the
range of engine and simulated flight conditions investigated. The rise
ratio in the lead-lag characteristic varied from 0.5 to 1.0, and the
time constant in the lead-lag varied from 0.1 to 0.4 second over the
same range of conditions.
INTRODUCTION
The successful application of the ram-jet engine as a propulsion
system for supersonic flight is dependent, to a great extent, upon the
development of engine control systems capable of maintaining a desired
mode of engine operation and minimizing departures from desired condi-
tions resulting from external and internal disturbances acting on the
engine-control system.
Prior to the design of a satisfactory control system, two things
must be determined: first, the parameters which can be used to control
the system; and second, the static and dynamic performance characteris-
tics of the system to be controlled. Analyses (refs. 1 and 2) have1 y i w 7 Y
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Vasu, G.; Wilcox, F. A. & Himmel, S. C. Preliminary Report of Experimental Investigation of Ram-Jet Controls and Engine Dynamics, report, October 25, 1954; (https://digital.library.unt.edu/ark:/67531/metadc62656/m1/2/: accessed April 25, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.