Actively stabilized isentropic supersonic inlet asisi
Download
1 / 26

ACTIVELY STABILIZED ISENTROPIC SUPERSONIC INLET (ASISI) - PowerPoint PPT Presentation


  • 129 Views
  • Uploaded on

ACTIVELY STABILIZED ISENTROPIC SUPERSONIC INLET (ASISI). PROGRAM OVERVIEW March 7, 2002. PROBLEM STATEMENT AND CONCEPT FOR FLOW CONTROL PROGRAM Elements & Responsibilities Brief Descriptions and Progress SOME TECHNICAL DETAILS (‘Appendices’). OUTLINE.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'ACTIVELY STABILIZED ISENTROPIC SUPERSONIC INLET (ASISI)' - tyme


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Actively stabilized isentropic supersonic inlet asisi
ACTIVELY STABILIZED ISENTROPIC SUPERSONIC INLET (ASISI)

PROGRAM OVERVIEW March 7, 2002

ASISI Overview


Outline

PROBLEM STATEMENT AND CONCEPT FOR FLOW CONTROL

PROGRAM

Elements & Responsibilities

Brief Descriptions and Progress

SOME TECHNICAL DETAILS (‘Appendices’)

OUTLINE

Northrop’s ‘dual relevant’ QSP concept, baseline for active inlet design and control studies

ASISI Overview


Initial concept for high efficiency inlet internal compression with little or no shock losses
INITIAL CONCEPT FOR HIGH EFFICIENCY INLETInternal Compression With Little or No Shock Losses

  • Less efficient, stable internal compression

normal shock d/s of throat: d = 0.94

boundary layer loss ~ 0.03

  • Highly efficient, unstable internal compression

no shock losses: d = 0.97

robust boundary layer at design

ASISI Overview


TRADE-OFF: INLET STABILITY VS. PRESSURE RECOVERY

  • Stability of uncontrolled inlet determined by shock position

move shock u/s

and control it

pressure recovery

increasing stability as

shock moves d/s

reducing exit static pressure

gain stability margin and performance using control

ASISI Overview


ESTIMATED COMPONENT PERFORMANCE BENEFITS

Propulsion Technology Areas Studied Under QSP Phase I

  • using optimized BPR at given c & component efficiencies:

† assumes 1% red. in TOGW through higher BPR

‡ assumes 2.5% red. in TOGW through fewer comp. stages and higher BPR

* internal cooling allows higher Tt4. Value quoted meets range target in conj. with aspir. compr.

ASISI Overview


Program goals and approach

OBJECTIVE:

97% Total Pressure Recovery at Cruise Condition

Minimize Stabilization Bleed

BENEFITS:

+2.5% or Better Recovery Improvement

+1.25% SFC Improvement  100+ NM Range Increase

30-60% Reduction in Required Stability Bleed

Sonic Boom Reduction

APPROACH:

Advanced Design of Reduced Stability, Increased Efficiency Inlet

Active Disturbance Rejection to Eliminate Unstart

Generalized Dynamical Analysis and Control Design Tools

LIMITED DATA RIGHTS

USE, DUPLICATION OR DISCLOSURE OF THESE DATA, IN WHOLE OR IN PART, AND IN ANY MANNER, IS FOR GOVERNMENT PURPOSES ONLY, AND TO HAVE OR PERMIT OTHERS TO DO SO FOR GOVERNMENT PURPOSES ONLY

PROGRAM GOALS AND APPROACH

ASISI Overview


Program elements
PROGRAM ELEMENTS

  • DIFFUSER DESIGN (MIT)

    • Develop a Viable, Near-Isentropic, Reduced Stability Design

  • CONTROL ARCHITECTURE DEVELOPMENT

    • Understand Unstart Phenomenology

    • Propose Control Strategy

    • Initial Simulation Studies (1D)

    • Next-Generation Model Development

  • EXPERIMENTAL DEMONSTRATION FACILITIES

    • 1/50th Scale Experiment

    • 1/12th Scale Experiment

ASISI Overview


Design challenges
DESIGN CHALLENGES

subsonic diffusion

  • Shock loss vs. viscous loss

    • Impacts length

  • Bleed requirement

    • Set by boundary layer thickness upstream of slot

    • Exit Mach number

  • Static stability

    • Choice of throat Mach, shock Mach

  • Aerodynamic shaping

    • Supersonic, subsonic regions

supersonic compression

  • Exit Mach ~ 0.55-0.6

M=2.2

Bleed slot

  • Shock system loss

    • Supersonic compression shocks

    • Terminal normal shock

  • Boundary layer loss

    • Long development along length

    • Shock-boundary layer interaction growth

    • Subsonic recovery

ASISI Overview


Current design concept design using same tools as aspirated compressor
CURRENT DESIGN CONCEPTDesign Using Same Tools As Aspirated Compressor

  • ASPIRATED, MIXED COMPRESSION DIFFUSER

    • Much shorter, reducing BL losses

    • Bleeds also reduce BL thickness, make more robust to variations

    • Shock losses offset BL gains ~ same recovery

    • Bottom line: lighter, more easily integrated inlet

  • MIXED-OUT PRESSURE RECOVERY = 97%, EXIT MACH = 0.55

  • STEADY BLEED REQUIREMENT = 4% OF INLET MASS FLOW

Shock Bleed 2%

Shock Bleed 1%

Control Bleed 1%

ASISI Overview


Phenomenology of unstart and concept for prevention
PHENOMENOLOGY OF UNSTARTAnd Concept for Prevention

  • TWO ROUTES TO UNSTART

    • If downstream pressure or upstream Mach number rise too high, shock moves up to throat, becomes unstable and blows out

    • If Mach number at throat falls below 1, a new shock forms at the throat, blows out the front and unstarts the original shock

      (See Movies Unstart.mpg and Unstart2.mpg)

  • ACTIVE CONTROL

    • Maintain throat mach number near it’s design value (perturbations to cancel propagate from upstream)

    • Maintain shock position (main perturbations that cause shock motion come from compressor face)

    • Initial studies indicate that bleed is a simple and effective actuator

    • Static pressure and perhaps temperature must be sensed

ASISI Overview


Active control system architecture

LIMITED DATA RIGHTS

USE, DUPLICATION OR DISCLOSURE OF THESE DATA, IN WHOLE OR IN PART, AND IN ANY MANNER, IS FOR GOVERNMENT PURPOSES ONLY, AND TO HAVE OR PERMIT OTHERS TO DO SO FOR GOVERNMENT PURPOSES ONLY

Sensors

Actuators

ControlComputer

Inlet Flow

Isentropic

Ramp

Bleed Flow

To Bleed Cavity

Bleed Slot

Control Actuators

Solenoid Actuator w/

Spring-Loaded Valve

(Densitron or Moog Servos)

Bleed Air to Subsystems

Bleed Cavity

ACTIVE CONTROL SYSTEM ARCHITECTURE

Continuous Isentropic Compression Surface

(Cruise Throat Position)

Terminal Shock

Takeoff Throat Position

ASISI Overview


Feedforward feedback control

LIMITED DATA RIGHTS

USE, DUPLICATION OR DISCLOSURE OF THESE DATA, IN WHOLE OR IN PART, AND IN ANY MANNER, IS FOR GOVERNMENT PURPOSES ONLY, AND TO HAVE OR PERMIT OTHERS TO DO SO FOR GOVERNMENT PURPOSES ONLY

Sensors

Actuators

ControlComputer

Solenoid Actuated

Bleed Valves

Static Pressure Ports

CompressorDisturbances

AtmosphericDisturbances

Terminal Shock

Controller

Downstream perturbationsAlso Feed ‘Forward’ (in Time)to Predict Shock Location

Correct Number of Bleed Valves Open to AbsorbDisturbance

Appropriate Control ActionFrom Remote and LocalActuators Stabilizes Shock

Upstream Disturbances AreDetected by SensorsFar From Throat

Feedback Signal FromThroat Provides Corrections+ Adaptation of Feedforward

Estimation RoutinesPredict Effect on Throat

Mach Number

Shock Motion Sensing + Prediction of UpstreamDisturbances Feeds Into

Shock Location Models

Bleed Air Flows toEnvironmental System

Controller Subtracts SystemDelays (Servo + Fluid Mechanical) to

Compute Time to Launch Cancellation Action

FEEDFORWARD / FEEDBACK CONTROL

Note: View in Slideshow Mode

ASISI Overview


Control system demo designs upstream control

USE 1D EULER CODE (FAST, SIMPLIFIED DYNAMICS)

IDENTIFY VARIOUS SYSTEM TRANSFER FUNCTIONS

Disturbance to Sensed Pressure

Disturbance to Throat Mach Number

Actuation to Throat Mach Number

USE TRANSFER FUNCTIONS TO DESIGN FEEDFORWARD CANCELATION TRANSFER FUNCTION

Invert out measurement dynamics, launch wave at appropriate time advance to arrive at throat simultaneous to disturbance

Ultimate implementation would require feedback to make robust

(See Movie Control.mpg)

CONTROL SYSTEM DEMO DESIGNS(Upstream Control)

ASISI Overview


Next generation model development
NEXT-GENERATION MODEL DEVELOPMENT

  • 1D SIMULATIONS

    • Improved accuracy of Euler scheme

    • Incorporate M profile from latest mixed-compression design

    • Incorporate actuation models from 2D simulations

    • Perform more detailed control studies

  • 2D SIMULATIONS

    • Develop actuation models for incorporation into 1D models

    • Develop reduced-order input-output models that capture physics in a model suitable for control law design

      • Arnoldi methods for CFD model order reduction

      • Extension to supersonic, possible nonlinear regime

    • Validate control laws designed in 1D

ASISI Overview


Atmospheric disturbance model
ATMOSPHERIC DISTURBANCE MODEL

  • Inlet Perturbations

    • Atmospheric, Angle of attack changes

  • Perturbation Characterization

    • Isothermal Horizontal, Vertical Gusts

    • Atmospheric speed of sound (temperature) change

    • Angle of attack (Da=Dv / U)

    • Inflow boundary condition is superposition of above perturbations

ASISI Overview


Open loop response to perturbation in atmospheric temperature
OPEN LOOP RESPONSE TO PERTURBATION IN ATMOSPHERIC TEMPERATURE

Control Point

actuator

ASISI Overview


Closed loop response
CLOSED LOOP RESPONSE

Control Point

actuator

ASISI Overview


ACTIVE CONTROL APPLIED TO 2D REDUCED-ORDER MODELDisturbance: atmospheric temperature variationsOutput: throat Mach number

  • Apply same method as previously demonstrated in 1D simulations

    • Model-based control design

    • Feed-forward inversion of sensor and actuator transfer functions

    • Goal: cancel disturbance before it reaches the throat

  • Challenges introduced by 2D

    • Currently canceling one output: average throat Mach number

    • Actuator effect on average throat Mach number is non-minimum phase: limits frequency range of cancellation

  • Capability demonstrated here:

    • Low order modeling for control system design

    • Feed-forward approach still works

ASISI Overview


Step input bleed propagation to throat 13 frames
STEP INPUT BLEED PROPAGATIONTO THROAT (13 FRAMES)

  • The effect of a step in bleed must travel across duct to get to throat – this results in A non-uniform distribution of response at the throat

  • The actuator characterization derived from simulations such as this will be incorporated into the 1D control design models, so that they account for the 2D effects

  • Slots run across entire span – 3rd dimension should not change behavior significantly

ASISI Overview


Step response of mach number at throat to 1 bleed step
Step Response of Mach Number at Throat to 1% Bleed Step

  • Mach number response at various spanwise stations (all at throat)

  • One time constant will ~characterize settling time of all stations

  • ‘Broadening’ of Mach no distribution (both in transient and SS) is detrimental to control system effectiveness

ASISI Overview


Wind tunnel setup and initial tests
Wind Tunnel Setup and Initial Tests

  • PURPOSE

    • Verify design recovery

    • Validate unsteady modeling (including actuation)

    • Psuedo-control tests (time scales too short for full implementation of control)

  • MIT FACILITY

    • 2.5”x4” Test Section

    • Mach no. up to 2.2

    • Blow-down for ~ 2 minutes

    • Retest every 30 minutes

  • STATUS

    • Shakedown with representative wedges complete

    • Test article in final stages of manufacture/assembly

Shown: Test section and focusingschleiren system

ASISI Overview


Wind tunnel setup and initial tests1
WIND TUNNEL SETUP AND INITIAL TESTS

  • PURPOSE

    • Verify design recovery

    • Validate unsteady modeling (including actuation)

    • Psuedo-control tests (time scales too short for full implementation of control

  • MIT FACILITY

    • 2.5”x4” Test Section

    • Mach no. up to 2.5

    • Blow-down for ~ 2 minutes

    • Retest every 30 minutes

  • STATUS

    • Test article assembled

    • Schlieren images of operation at design point and unstart

Shown: Test section with assembled inlet

ASISI Overview


1 50 th scale test article
1/50TH SCALE TEST ARTICLE

Transpiration

  • Kulite transducers: Inlet, throat, exit

  • Piezo-actuators provide bleed flap excitation

  • Upper surface bleed to maintain boundary layer attachment

  • Throttle at exit to control static pressure boundary condition

Throttle

Kulites(3 places)

Piezo Stack

Actuators(2 places)

Bleed Flaps

ASISI Overview


Test article
TEST ARTICLE

  • Kulite transducers: Inlet, throat, exit

  • Piezo-actuators provide bleed flap excitation

  • Upper surface bleed to maintain boundary layer attachment

1 inch

Throttle flap

Bleed Flaps

ASISI Overview


Test article1
TEST ARTICLE

Movable Upper Surface

Flow

Direction

Bleed Flaps

5.5 inches

4 inches

Kulite Transducer

Bleed Flaps

ASISI Overview


Gtl supersonic flow loop

FACILITY FOR 1/12th SCALE TESTING

Required to achieve tractable time scales for control

WILL REFURBISH HEAT EXCHANGERS, DRYERS, ETC.

NEW TEST SECTIONTO DESIGN: NON-STANDARD ASPECTRATIO, WITH ACTUATION

GTL SUPERSONIC FLOW LOOP

Diffuser

Test Section (4” by 4”)

Compressor (~13 lb/sec)

ASISI Overview


ad