Active Inlet Control
For High Speed Civil Transport, the efficient and safe operation of the engine requires that the leading shock
at the engine inlet be maintained within a narrow range of locations at the inlet face. If the shock moves too
far out in front of the inlet, it results in a phenomenon called inlet “unstart” where there is no flow to the
engine and the engine shuts down resulting in violent motions of the aircraft. The active inlet controls program
is being conducted in direct support of the NASA High Speed Research (HSR) program which is developing technologies
for a future commercially and environmentally viable supersonic civil transport aircraft.
The objective of the active inlet control program is to develop and validate dynamic models and advanced
multivariable control systems for supersonic mixed-compression inlets. The control system will be designed
to include inlet unstart prevention, automatic restart, distortion minimization and inlet/engine integrated
control. The technologies are to be demonstrated through wind-tunnel tests on scaled versions of variable
geometry inlet concepts developed by Boeing. Some of the challenges in implementing active inlet control are
determining the best effectors for controlling the shock position and developing accurate models of inlet
operation to be able to estimate shock position from pressure measurements.
- Develop a multivariable control design methodology for HSCT
inlets which includes unstart prevention, automatic restart,
distortion minimization, and inlet/engine integrated
- Define and validate dynamic models of candidate HSCT inlets
which capture the effects of unstart, restart, buzz,
variable geometry, bleed and distortion.
- Validate inlet modeling and controls via supersonics wind
- Conduct inlet/engine operability studies to demonstrate
acceptable propulsion system performance in projected HSCT
- Designed multivariable control system for 2-D Bifurcated
Two-Stage Supersonic Inlet (BTSSI).
- Successfully demonstrated control system for BTSSI in 10x10
- Developed procedure for linear model generation from
nonlinear model for use in control design (Grant).
- Generated two-duct LAPIN-code inlet model for 2-D HSR inlet
and delivered to industry partners.
- Completed initial plan for inlet control operability study
for axisymmetric inlet to support HSR inlet down-select
Kevin J. Melcher
NASA Glenn Research Center/77-1
21000 Brookpark Road, M.S. 77-1
Cleveland, Ohio 44135
phone: (216) 433-3743