The propulsion control system affects the economics of the HSCT through the mechanisms indicated. Weight reduction is paramount in an aircraft of this type. Significant reductions are possible relative to the SST or even current technology if improvements are made in areas such as high temperature electronics. Dependability is an increasingly important parameter in all aircraft, but the higher capital cost of the HSCT makes it doubly important. Conversely the more difficult HSCT design problem makes it more difficult to achieve. Integration of propulsion controls will make it possible to improve both the static and dynamic performance of the HSCT propulsion system. Noise and emissions requirements may introduce novel control system requirements such as automatically programmed takeoff thrust for noise abatement. Control system development technology is evolving. For HSCT, highly automated and thoroughly validated tools will be required to reliably achieve desired system performance at introduction, and to reduce development costs. A technology plan was developed to prepare for HSCT development. This presentation addresses the portion of the plan required to demonstrate technology readiness for the HSCT in the late 1990's rather than the technology development currently in progress

Carlin, Christopher M.

English

NASA Technical Reports Server

N94. 335
/_ 0 _ 3
HSCT INTEGRATED PROPULSION CONTROL ISSUES
_c-. ______._L:_ __
C.M. Carlin
Boeing Commercial Airplane Group
16 May, 1991
PRECEDING PAGE BLANK NOT FILMED
1507
https://ntrs.nasa.gov/search.jsp?R=19940029004 2020-06-16T13:09:39+00:00Z
F_ -_¸
OVERVIEW
The propulsion control system affects the economics of the HSCT through the
mechanisms indicated. Weight reduction is paramount in aircraft of this type.
Significant reductions are possible relative to SST or even current technology
if improvements are made in areas such as high temperature electronics.
Dependability is an increasingly important parameter in all aircraft, but the
higher capital cost of the HSCT makes it doubly important. Conversely the more
difficult HSCT design problem makes it more difficult to achieve. Integration
of propulsion controls will make it possible to improve both the static and
dynamic performance of the HSCT propulsion system. Noise and emissions
requirements may introduce novel control system requirements such as
automatically programmed takeoff thrust for noise abatement. Control system
development technology is evolving. For HSCT, highly automated and thoroughly
validated tools will be required to reliably achieve desired system performance
at introduction, and to reduce development costs.
A technology plan has been developed to prepare for HSCT development. This
presentation addresses the portion of the plan required to demonstrate
technology readiness for the HSCT in the late 1990's rather than the technology
development currently in progress.
OVERVIEW
o Technical Issues
Weight
Dependability
Performance
Noise/Emissions
Control System Development
1508
o Technology Plan
Simulation
Control Laws
Architecture
Component Development
Technology Demonstration
PROPULSION CONTROL AIRPLANE LEVEL ISSUES
The weight of the SST control system was concentrated in long wire runs from
fuselage mounted electronics to nacelle mounted actuators and sensors, and in
the actuators themselves. Dependability will be improved through accurate
knowledge of disturbances, validated simulations, highly reliable components
operating in a well understood environment, and reducing system parts count.
Performance improvements are available either through reduced component
operating margins or by improving system off design performance through
integration and optimization. Noise abatement introduces requirements for
automatic thrust profile management, and relatively complex nozzle
configuration management. Control system development is currently a complex,
labor intensive, and costly process. The tools used need to be improved,
validated, and integrated to permit reliable automated analysis, design, build,
and test. The propulsion control development process also needs to become
more analytical to reduce dependence on the wind tunnel and test cell.
PROPULSION CONTROL AIRPLANE LEVEL ISSUES
o Weight
SST Total Intake Control System - 4442 Lbs
1782 Lbs of Wire
2066 Lbs of Actuation Equipment
o Dependability
Unstarts,Stalls,and Flameouts are unacceptable
o Performance
Reduced Control Margins
Integrated & Optimizing Controls
o Noise & Emissions may introduce novel control requirements
0 Control System Development
Reduce development cost through automation
Minimize interdependence between controls
and machinery development
1509
INLET CONTROL SYSTEM WEIGHT
SST control system weight was largely caused by long wire runs and actuation
requirements. High temperature electronics, if available, would permit
mounting multiplex/control units in the nacelles, eliminating long multiwire
bundles. Fiberoptic sensors would permit reductions in the size, and weight of
long wire runs by eliminating HERF/EMI considerations. Depending on the
development of the technologies some combination of them should significantly
reduce the wire weight of the propulsion control system. In the event none of
the advanced technologies become available air or fuel cooling of nacelle
mounted electronics is a practical but less than desirable solution to the
problem. Light weight, probably composite, actuation along with relatively high
pressure hydraulics are required to reduce actuation weight. Actuation weight
may also be reduced by reducing actuation dynamic response requirements. This
may be achieved by coordination of airframe,inlet,engine, and nozzle operation
and by anticipation of system disturbances.
INLET CONTROL SYSTEM WEIGHT
Inlet Control
SST Design Electronics
_icated Analog
"_,,,,_:_ Wire Runs
Actuators- & _ I
Sensors
o Weight reduction requires technology advances
High temperature electronics
Severe environment fiberoptic sensors and data buses
Reduced sensor set
Lightweight actuation
o Without technology advances actively
cooled electronics will be required
1510
HSCT PROPULSION PERFORMANCE
The turbine bypass engine/mixed compression inlet propulsion system depicted
is probably the simplest HSCT propulsion system configuration under study. It
presents a multivariable control problem in both the steady state and dynamic
sense. When operating on design at steady state the desired operating position
for each element of the system is well defined. Bypass doors are shut, turbine
and compressor operate at their design match points, etc. However as the
system operates off design, either due to deviations from the optimum flight
path, temperature variations, or during climb and descent a non trivial optimum
selection process is required to distribute captured airflow to achieve the best
(thrust-drag)/fuel flow possible while satisfying stability margin
requirements on various elements of the system. The fact that each effector
from the centerbody to the exhaust nozzle has an effect on the set of states
which define engine operating condition makes the control design problem
inherently multivariable. There is significant coupling between the airframe
and propulsion system not only through thrust commands, but also through
angle of attack and Mach number influences on the inlet and inlet bypass
contributions to yawing and rolling moments. Application of multivariable
design techniques is expected to permit reduction of actuator bandwidth
requirements and control margins, thus improving weight and performance.
Development of a control system for this system will require an accurate,
relatively high bandwidth, propulsion/airframe simulation including
representation of major non-linear phenomena such as unstart and surge.
1511
HSCT PROPULSION PERFORMANCE
Throat mach Normal shock position
determines recovery determines distortion&
recovery
Shock structure _ \ .....
_,,__,_., L.. _ \ L;ompressor varlaole geometry
variation _2 __
Centerbod_, _-_----_-_,_---/ _=_-_, -"/] ' " /-
• SpillaJge . ]_ue]flflow Thr°at ar/ea Exit/area
/ • ] _Secondary airflow valves
_yypass doors "
o Propulsion system is physically coupled both internally and externally
o Integrated propulsion/airframe control +
Best performance for given control margins,sensors,and actuation capability
Self optimising for off design conditions
o Analysis requires integrated high fidelity simulation
1512
ADVANCED INLET INSTRUMENTATION
The critical measurement in a mixed compression inlet is normal shock
position. Historically this has been measured by sensing the static pressure
rise associated with the normal shock. This approach, although workable,
suffers from deficiencies including complex plumbing, relatively low
bandwidth, high precision requirements and sensitivity to angle of attack, inlet
geometry variations, and minor inlet design changes. More direct approaches to
normal shock sensing, suited to the low terminal shock mach numbers of the
HSCT inlet, could benefit both system performance, by reducing supercritical
margin, and dependability, by eliminating plumbing and fragile pressure
transducers.
Mixed compression inlet throat mach number margin is set by the anticipated
magnitude and rate of change of freestream mach number variations and the
bandwidth of the centerbody actuator. If techniques can be developed which
allow us to detect freestream variations substantially ahead of the airplane we
can reduce throat mach number margin and the dynamic response requirements
on the centerbody actuation system. Optical techniques show promise for
providing this kind of prediction capability. Unfortunately current systems are
heavy and are dependent on aerosols which may not have adequate density to
assure a continuous signal. If available such system would also benefit flight
control system performance.
ADVANCED INLET INSTRUMENTATION
o NORMAL SHOCK SENSOR
High bandwidth
Eliminate plumbing & manifolds
Minimize signal sensitivity to inlet design changes
o FREESTREAM DISTURBANCE DETECTION
Throat mach tolerance dictated by:
disturbance frequency content
actuator bandwidth
anticipation available
Approach
Temperature - infrared imaging
Wind shear - laser backscattering
Issues
Complexity/weight & aerosol availability
Other potential benefits
Clear air turbulence avoidance
Improved autopilot performance
1513
CONTROL SYSTEM DEVELOPMENT OBJECTIVES
For the most part adequate control simulation and analysis tools exist to
perform the propulsion control system design, analysis, build, test task.
Unfortunately, although the individual tools exist, they are not integrated into
a system that permits automation of the control system development process
starting from the CAD data base for the propulsion plant. Furthermore many of
the tools are proprietary and individuals in a given organization are familiar
only with their own tools, in order to efficiently develop an HSCT control
system an integrated package available across corporate boundaries must be
created. Such a system will reduce development costs and produce a more
reliable high quality product.
Current propulsion system development practice is strongly dependent on test
results to establish component performance, pneumatic signal characteristics
used for airflow and normal shock measurements, and to confirm system
dynamics. Significant development economies can be achieved by using CFD to
predict these characteristics and using the wind tunnel/test cell only as a
final confirmation tool.
CONTROL SYSTEM DEVELOPMENi OBJECTIVE-°,
o Automate the design analysis build test process
Integrate and validate existing tools
Modify or develop tools if required
Benefits cost and reliability/quality
o Reduce dependence on tests involving propulsion machinery
Integrated tests of developmental machinery
and developmental controls are costly and risky
Use CFD to reduce dependence on wind tunnel
and flight test results
1514
RECOMMENDED HSR PROGRAM
As indicated in the early charts significant technology improvements are
anticipated in the next 5 years to improve the development and operating
economics of the HSCT. Before these technologies can be applied in a production
program a demonstration program to validate them is required. The
recommended HSR program consists of four to five years of technology
development, and a five year technology demonstration program. Some of the
technology development efforts are already under way in programs such as the
NASA/NAVY FOCSI program and the NASA HIDEC/PSC program. Other technology
development efforts in areas such as high temperature electronics and
improved normal shock sensing need to be initiated rapidly if they are to be
useful to the HSCT on the planned schedule. The technology demonstration
program would be based on a complete supersonic propulsion system, and its
integrated control including examples of all desirable advanced technology
components. The system would be exercised through a complete test cycle
starting with a control hardware in the loop bench test, and culminating in a
flight test on an appropriate aircraft. The design, development, and test
activity would provide the necessary validation of the integrated control
development tool, the design methodology, and component technologies.
RECOMMENDED HSR PROGRAM
I 19911199211993 I 1994l 19951 1996J 199.71_1998l1999 ]2000 I
Concept Dev.
Component
Development
Integrated Control System Technology Demonstration
Design _Fab ./" Test
[PAIT Additions]
IExisting NASA Programs ,_
JNASA/Corporate cooperatio_T, /
/J Corporate IR&D
o Features:
Integrated Prop/Fit Control Law
Full envelope capabiliy
Related displays and controls
Critical system component tech
Fiberoptics
High temperature electronics
o Approach:
Representative Aerodynamics
and Propulsion Cycle
Implement multiple solutions
Subscale propulsion system
Test on NASA facilities & aircraft
1515
FLIGHT TEST DEMONSTRATION OBJECTIVES(I)
A flight test demonstration provides the opportunity to confirm a large number
of propulsion system issues which are not specifically control related. These
include validation of the analytical techniques use to design the cycle and
propulsion components and predict thrust minus drag. An opportunity is also
provided to confirm noise prediction techniques for impingement on the
aircraft and the ground. The opportunity is provided to see the complete system
in operation and identify any unexpected environmental effects on components
and to understand the real world maintenance situation.
FLIGHT TEST DEMONSTRATION OBJECTIVES(I)
DEMONSTRATE INSTALLED PROPULSION SYSTEM PERFORMANCE
o Validate analytical techniques
o Confirm wind tunnel results
o Confirm engine/inlet compatability
o Operation in real world environment
o Acoustic impingement on adjacent structure
o Noise prediction
o Thrust - drag accounting verification
1516
FLIGHT TEST DEMONSTRATION OBJECTIVES(II)
From a control standpoint there are a number of flight test objectives.
Confirmation of analytical techniques, in particular those involved in
predicting the installation effects both on the inlet flow field and installed
thrust drag, is critical to reducing risk in the production program.
Demonstration of the integrated control system with the pilot in the loop in the
flight environment is also extremely critical since the system will have a
number of novel pilot interface features and control modes relative to current
commercial practice. Finally the demonstrator is critical to demonstrating the
practicality of advanced hardware components in the supersonic environment
on a closed loop basis.
FLIGHT TEST DEMONSTRATION OBJECTIVES(2)
PROPULSION CONTROLS
o Confirm analytical techniques
o Demonstrate integrated inlet/engine/nozzle/flight control system
o Demonstrate system automation &display features
o Obtain pilot evaluation of integrated system
o Demonstrate system operability
o Demonstrate advanced component technology
High pressure hydraulics
Fiberoptics
Light weight actuators
Normal shock sensor
High temperature electronics
Advanced data bus
High temperature connectors & wiring
Freestream disturbance detection
1517
CONCLUSIONS
Substantial component development effort is required if HSCT control system
weight and performance are to be significantly improved over that of the SST.
An integrated control system development package including simulation,
analysis, and autocode tools is required to reduce development costs and
improve system reliability. This development package must be shared among all
participants in HSCT control system development. A controls demonstration
program is required to confirm both the advanced component technologies and
the control system development methodology prior to undertaking a full scale
commercial development program. Further NASA and industry planning of the
next ten years research effort in this area is required.
CONCLUSIONS
COMPONENT DEVELOPMENT IS REQUIRED
o Fiberoptic sensors
o High temperature electronics
o Direct shock sensing
o Freestream disturbance detection
o Lightweight actuation
o Fiberoptically signalled actuation
o Advanced data buses
SIMULATION,ANALYSIS, AND DEVELOPMENT TOOLS
o Integration,improvement, and validation are required
CONTROLS DEMONSTRATION PROGRAM REQUIRED
o Prove methodology & design/analysis tools
o Demonstrate advanced hardware technology
in realistic environment
o Validate HSCT economic factors related
to propulsion control
o Flight test required for complete demonstration
FURTHER PLANNING IS REQUIRED
1518
Session XI. Airframe and Engine Materials
1519
THIS PAGE INTENTIONALLY BLANK
1520


HSCT integrated propulsion control issues

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server