Date: Slide 1

Turbine-Based Combined-Cycle Large-scale Inlet Mode Transition

(CCE‐LIMX)Phase 3 Testing update

Dave Saunders, Lance Foster and Dr. Thomas StueberNASA – Glenn Research Center

April 15th, 2015

Combined Cycle Engine Large Scale Inlet Mode Transition Experiment (CCE LIMX) in the GRC 10x10 SWT

• What is TBCC?

• Answering the Heilmeier Questions for CCE-LIMX

• Background of CCE-LIMX Phases 1 and 2

• CCE-LIMX Phase “3a” Objectives and Plan

• CCE-LIMX Phase “3b” Objectives and Plan

• Summary

Presentation Outline

Turbine-Based Combined Cycle Concept

Slide 4

CCE-LIMX Heilmeier Questions• What is the near-term objective of the Combined-Cycle Engine (CCE) project?

Develop closed-loop control to enable smooth & stable inlet operation throughout mode transition schedule without unstart for Turbine-Based Combined Cycle (TBCC) propulsion.

• What is the state-of-the-art and limits?Early testing with CCE demonstrated open-loop control. Industry concepts are at planning and design stages with some limited inlet characterization test and CFD results.

• What's new about the upcoming CCE testing?Closed-loop control is an important first step to build a capability to demonstrate an integrated TBCC propulsion system.

• Why will it be successful?Successful completion of Phases 1 and 2 testing and experienced team with critical industry partners have developed a rational test approach to integrated TBCC propulsion control.

• Who cares?Funding from DoD (Air Force Research Lab, DARPA) with NASA infrastructure support and hypersonic funding in following years.

• If you're successful, what difference will it make?TBCC propulsion control is key technology for very long range missions and efficient access-to-space.

• What are the risks and the payoffs?Risk is lack of a near-term driving need that affect funding. Payoff is better positioning of nation to respond to a need for routine global reach or access-to-space vehicles.

• How much will it cost?Near term testing level is about $9M. Engine integration testing (unfunded) would need another ~$15M. Flight-like ground testing with vehicle focus ~$30M. Flight demonstration could be on the order of $100M’s.

• How long will it take?Phase 3 testing began April 11, 2015. This phase of testing should be completed by December, 2015. Engine Integration testing would take about two more years at current anticipated funding levels.

• What are the midterm and final "exams" to check for success?Midterm success criteria is the demonstration of closed-loop inlet control. Final success would be demonstrating smooth, unstart-free mode transition with operating engines.

Your Title Here

High-speed ramp &

flowpath

Low-speed ramp &

flowpath

High Mach Turbine Simulator

or Engine

Dual-Mode

Scramjet Simulato

r

CCE-LIMX Model in GRC 10x10-ft Wind Tunnel

Combined Cycle Engine Large Scale Inlet Mode Transition Experiment (CCE LIMX) in the GRC 10x10 SWT

TEST APPROACH- 4 PHASES

1. Inlet performance and operability characterization

2. System identification of inlet dynamics for controls

3. Demonstrate control strategies for smooth & stable mode transition without inlet unstart

4. Test inlet integrated with Mach 3 turbine engine and nozzle (and simulate scramjet with mass flow plug)

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CCE-LIMX Mode Transition Testing in 10x10-ft Wind Tunnel

Phase 3aPhase 3a CCE-LIMX Testing CCE-LIMX Testing

Planned Apr 2015-Jun 2015Planned Apr 2015-Jun 2015

Phase 3bPhase 3b CCE-LIMX Testing CCE-LIMX Testing

Planned Sep 2015-Nov 2015Planned Sep 2015-Nov 2015

Phase 4 CCE-LIMX Testing, TBD

Definitions:Phase 1- Inlet Performance CharacterizationPhase 2- System Identification TestingPhase 3- Closed-Loop Controls TestingPhase 4- Integrated Inlet/Turbine Engine Testing (UNFUNDED)

GRC/AFRL Space Act Agreements for Phase 3a Testing signed in Nov, 2013 & for Phase 3b Testing signed in Nov, 2014

Phase 1 CCE-LIMX Testing

Mar 2011-Jun 2011

Phase 2 CCE-LIMX Testing

Aug 2011-May 2012

Small Scale IMX Model 1’x1’ SWT Testing

May – October, 2007

Slide 7

Timeline for CCE-LIMX Research

Background: Phases 1 and 2

What was accomplished• Focus was on Mach 4, 95% of testing

• Inlet performance and stability characterized including AoA• Mode transition schedules developed for both turbine and ramjet

flowpaths

• Mach 3 only briefly investigated • A Mode transition schedule was developed• High steady-state distortion identified

• A Mach 3 bleed configuration was used to reduce distortion• Dynamic data acquired intermittently, throughout• System Identification data acquired to characterize the inlet dynamics

• linear control design models developed, suitable for closed-loop control• control is compatible with inlet dynamics

• Mode transitions was demonstrated with open loop (scheduled) control• Many operational lessons were learned

Next step: focus on closed-loop controlled mode transition and turbine engine preparations

Slide 8

PRIMARY OBJECTIVE for phase 3a

• Test and tune closed-loop control to enable smooth & stable inlet operation throughout mode transition schedule without unstart. For the CCE-LIMX model, unstart coincides with ‘buzz’, a dynamic instability.

• A key complexity of Phase 3 is to achieve closed-loop control of the normal shock position in the inlet for the turbine flowpath.

 SECONDARY OBJECTIVES (if schedule and budget allow. These become primary objectives for phase 3b).

• Improve distortion characteristics through an alternate mode transition schedule.

• Measure dynamic distortion with a full set of AIP dynamics . Enabled with AFRL augmentation funds.

• Improve linear measurement accuracy and reliability. From earlier testing, the currently available potentiometers have a high failure rate due to the wind tunnel environment, (temperature ~300oF and vibration).

• Determine levels of distortion and unsteadiness in the high-speed flowpath. This objective would be addressed by enhancing the existing database on the high-speed flowpath through increased or novel instrumentation. Partially enabled with AFRL augmentation funds.

• Test to prepare for system integration strategy with a turbine engine.

Required for test success

Slide 9

CCE-LIMX Phase 3a Test Objectives

Pre-compression Pre-compression forebody plate (with forebody plate (with

AOA)AOA)Low-speed plugLow-speed plug

High-speed plugHigh-speed plug

Ducting to variable geometry Ducting to variable geometry bleed exits, all exitsbleed exits, all exits

High-speed High-speed cowlcowl

Low-speed Low-speed cowl cowl

Pivot for AOAPivot for AOA

Overboard Overboard BypassBypass

Variable rampVariable ramp

For Phase 3a: the model will be returned to prior configuration with refurbishment of the seals, instrumentation, AIP rakes with the following exceptions:

• Fix the forward bleed flow exit areas (plugs)• Added 10 dynamic pressures to the DMRJ isolator duct

F l o w

Variable geometry for inlet mode transition

Slide 10

Changes to CCE-LIMX model for Phase 3 Testing

R1

R4R3R2

SW1

C1C2

SW2SW3

Ramp surface

Sidewall surface

Cowl surface

RX

Ramp shoulder

Low-Speed Inlet Bleed Compartmentation

Multiple bleed regions in the turbine or low-speed inlet flowpath reduce adverse effects of SWBLI’s (Shock Wave Boundary Layer Interactions)

Slide 11

Control System Variables & SignalsControl System Variables & Signals

Propulsion system variables for mode transition control: sensors, and scheduled or closed-loop control

1. Freestream Mach number sensor

2. Angle of Attack sensor

3. Low-speed ramp angle scheduled

4. Unstart sensor sensor

5. Low-speed inlet variable cowl lip scheduled - master

6. Inlet bleed system scheduled

7. Low-speed inlet duct pressure sensor (feedback)

8. Engine back-pressure simulator (plug) scheduled

9. High-speed cowl variable lip scheduled

10. Isolator surface pressure sensor (feedback)

11. Isolator back-pressure simulator (plug) closed-loop control

12. Overboard bypass closed-loop control

Slide 12

Phase 3a – Test MatrixPhase 3a – Test Matrix

15 run days are allocated

Closed-loop control (10 run days)• Verify Mach 3 inlet configuration performance• Tune controller for responsive suppression of downstream disturbances for one, two and all four bypass doors.• Collect data to analyze robustness of closed-loop controller• Collect data to compare open-loop vs closed-loop stability margins• Demonstrate effectiveness of closed-loop control for rejecting

disturbances while following Mode Transition schedule for one and all four doors

Concurrent near-real-time dynamic distortion assessment

If time allows: • alternate mode transition schedules to improve dynamic

distortion.• Mach 4 investigation of isolator dynamics

Test matrix will accomplish primary objective and should also contribute to other secondary engine preparation objectives

StatusStatus

Model moved toModel moved toTest section, 7/5/14Test section, 7/5/14

Slide 13

Modified Williams International

WJ38-15 Turbine Engine

•modified from original subsonic engine.

•Limited to Mach 3 operation.

•limited-life.

•size similar to STELR engines.

•currently available (in a crate at GRC).

•tested at Williams at SLS conditions.

•the Spiritech SERN nozzle installed.

•50% afterburner operated at SLS.

WI turbine mounted on a static test stand, and the integrated nozzle assembly.

Spiritech SERN nozzle for the engine

Background: High-Mach Turbine Engine

Slide 14

Phase 3b – Risk Reduction for Engine Integration

Splitter Cowl lip

Critical additional risk reduction for turbine engine testing• Identified during Phase 3

pre-test analysis• Current mode transition schedule

exceeds turbine engine distortion limits

• Mitigation planning is underway• Engine integration startup, operating

and hazard recovery proceduresare being planned

‘Cloud’plot

‘Cane’curves

Slide 15

• Identify preferred Mach 3 mode transition sequences• Ensure compatibility with modified WI WJ-38 dynamic distortion requirements• Establish geometry scheduling and timing sequences for inlet mode transition

• Obtain data to define safe tunnel, engine, and inlet operation• Establish procedures for normal tunnel, engine, and inlet operation (i.e., startup,

windmill, ignition, shutdown)• Document tunnel, engine, and inlet control during transient test events (i.e.,

unexpected unstart, stall, flameout, etc.)

• Characterize dynamic response of DMRJ/SJ isolator during inlet mode transition

Identify potential challenges to ignition and operation Characterize isolator inflow and outflow pressure profiles

• Tunnel envelope expansion Tunnel Mach to 3.5 with angle to get model Mach of 3 with higher dynamic

pressure Gather Inlet mode transition data at lower Mach #s (<3) per external

developments

‘Minimum Cost’ Testing Required Prior to Engine IntegrationSlide 16

CCE-LIMX Phase 3b Test Objectives

Phase 3a research is planned and ready or on-schedule for successful demonstration of closed-loop control during inlet mode transition.

• Testing will focus on mode transition at Mach 3 speeds• Closed-loop control research is prepared for mode transition inlet control• Secondary objective, where possible data will be acquired to understand:

• High levels of dynamic distortion at Mach 3 and develop approaches to mitigate. Six approaches will be investigated

• High-speed isolator dynamic distortion• Engine integration strategies

• Phase 3a testing is planned to begin April 10, 2015.

The plans leverage the successful results from Phases 1 and 2 which confirmed good performance and demonstrated smooth mode transition for the TBCC inlet.

As much as possible, Phase 3b plans will simulate engine operations. Testing is planned to begin shortly after phase 3a testing.

Summary of Phase 3 plansSummary of Phase 3 plans

Slide 17

Slide 18

Questions?