Preliminary report of experimental investigation of ram-jet controls and engine dynamics Page: 3 of 71
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2 NACA RM E54H10
indicated some ram-jet engine parameters which can be used for control
purposes and also some of the techniques possible in applying these
parameters in control loops.
In order to determine the dynamics of ram-jet engine performance and
to ascertain the practicability of several control techniques, an experi-
mental investigation was conducted.on a full-scale ram-jet engine in the
8- by 6-foot supersonic wind tunnel of the NACA Lewis laboratory. The ob-
jective of the engine dynamics portion of the experimental program was
to ascertain the nature of the response of the internal pressures of
the ram-jet engine to disturbances of the engine independent variables
(fuel flow, angle of attack, Mach number, aid exhaust-nozzle area).
The controls portion of the program was designed to evaluate the steady-
state and dynamic performance characteristics of three different control
techniques: (1) shock positioning, (2) direct control of diffuser pres-
sure recovery, and (3) "optimalizer" control of diffuser pressure re-
covery. The latter two techniques are described in reference 2.
APPARATUS AND INSTRUMENTATION
Engine and Installation
The engine used in the test program was a 16-inch-diameter ram jet -*
and is shown mounted in the 8- by 6-foot supersonic wind tunnel in fig-
ure l(a). A detailed description of the engine and its performance is
given in reference 3.
The inlet was designed so that the oblique shock generated by the
250 half-angle conical spike fell slightly ahead of the cowl lip at the
design Mach number of 1.8. The engine had a conical exhaust nozzle with
an exit area of 0.69 of the combustion-chamber area. Reductions in exit
nozzle area up to 21 percent were obtained by the use of a movable water-
Engine angle of attack could be varied from zero to 100 by rotating
the engine about a pivot point in the support strut. By use of the
inclined-plate technique described in reference 4, the Mach number of
the free stream entering the engine could be varied rapidly by pitching
the engine with plates attached to an angle of approximately 50. Two
plates were used; the first provided a range of Mach numbers from 1.7 to
1.9, and the second, from 2.0 to 2.16.
Internal features of the engine are shown in figure l(b). The en-
gine was equipped with a can-type burner. Engine air flow and diffuser-
exit total-pressure recovery were evaluated at station x located 57
inches downstream of the cowl lip. Combustion-chamber-inlet conditions
were based on the flow area of station 3. Static-pressure taps used in
IW WM We
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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; (digital.library.unt.edu/ark:/67531/metadc62656/m1/3/: accessed September 21, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.