USM3D-ME Analyses Performed in Support of a Wind Tunnel Test of a Boundary-Layer Ingestion Configuration

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LANGLEY RESEARCH CENTER

USM3D - ME Analyses Performed in Support of

a Wind Tunnel Test of a Boundary - Layer

Ingestion Configuration

Michael D. Bozeman Jr.

NASA Langley Research Center, Hampton, VA

2024 AIAA Aviation Conference

July 31, 2024

LANGLEY RESEARCH CENTER

Outline

• Introduction

• National Transonic Facility (NTF) Wind Tunnel Test

– Experimental Setup

• Methods

– USM3D - ME Flow Solver

– Grid Generatio n

• Results

– Grid Refinement Study

– NTF Condition Sweeps

• Summary and Conclusions

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INTRODUCTION

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Introduction

• Boundary Layer Ingestion (BLI) technology offers potential fuel burn

reduction resulting from lower momentum flow ingested by the propulsor

• NASA is currently investigating the BLI technology with the goal of

quantifying the potential benefit offered by this technology

• As a first step, a wind tunnel test was performed in the National

Transonic Facility (NTF ) to:

– I nvestigate the flow ingested by an aft - mounted propulsor configuration

– P rovide a database to enable validation of our computational tools

• This work focuses on comparisons of USM3D - ME solutions to the

experimental data obtained from the NTF wind tunnel test of an aft -

mounted propulsor configuration

Single Aisle Turboelectric Aircraft Concept

with Aft Boundary - Layer Ingestion

(STARC - ABL)*

* Welstead , J. R. and Felder, J. L., “Conceptual Design of a Single - Aisle Turboelectric Commercial Transport with Fuselage Boundary Layer Ingestion,” 54th AIAA Aerospace Sciences Meeting, AIAA 2016 - 1027, 2016. doi:10.2514/6.2016 - 1027.

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NTF WIND TUNNEL TEST

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CRM - TCT Model

• Common Research Model with

Tail Cone Thruster (CRM - TCT)

– Variant of CRM with an aft - mounted

nacelle

– Representative of the STARC - ABL

concept

• CRM modifications include:

– Flow - through nacelle with mass flow

plugs (MFPs) to vary mass flow rate

Cruise MFP

90% Cruise MFP

– 4” extension added to CRM fuselage to

accommodate under chin support

– Empennage from Transonic Truss -

Braced Wing (TTBW) concept utilized

to accommodate tail cone thruster

Idle MFP

110% Cruise MFP

– Clean configuration (no tail cone

thruster) also investigated

• Modular nacelle assembly

including four MFP variations

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48 - probe AIP Rake

• Aerodynamic Interface Plane (AIP), located at the nacelle highlight,

instrumented with total pressure probes

• Primary AIP rake included eight struts and 48 probes

– Other rakes investigated include a six - strut rake with 27 probes, and a 5 - hole probe rak e

• AIP rakes rotated in experiment to provide high - resolution pressure data

– Rakes rotated by 45 degrees in 2.5 increments

• More details found in Chan*

6 6 5 5

Normalized

2 4 4

1 Probe Radius (in.)

3 3

Radius (r/R)

C 1 1 0 ° D B 45 ° 315 °

1 0.747 0.4527

1 2 3 4 5 6 1 2 3 4 5 6 270 ° 90 ° A E

2 0.872 0.5285

225 ° 135 ° H F 180 °

3 1.024 0.6206

G 2 2 2 4 4

4 1.241 0.7521

5 1.425 0.8636

6 1.588 0.9624

*Chan , D. T., Jones, G. S., Langston, S. L., and Kwok, A. K., “Experimental Investigation of a Boundary Layer Ingesting Tailcone Thruster Configuration at the National Transonic Facility,” AIAA Aviation 2024 Forum, 2024.

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METHODS

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USM3D - ME Flow Solver

• Mixed - element USM3D (USM3D - ME) is a 3D, unstructured flow solver

developed at the NASA Langley Research Center

– Cell - centered, finite volume Reynolds - averaged Navier - Stokes (RANS) solver

– Allows for variety of element types including tetrahedral, prismatic, hexahedral,

and pyramidal elements

• Variety of inviscid flux schemes and flux limiters available

– Roe scheme with no limiting employed for this work

• Turbulence closure options include variations of Spalart - Allmaras model

– One equation Spalart - Allmaras model with negative provisions, rotation correction, and

Quadratic Constitutive Relation (SA - neg - R - QCR) selected as baseline model for this work

– Turbulence model study additionally considered the SA model with negative provisions

without correction (SA - neg) and with the rotation correction (SA - neg - R)

• Hierarchical Nonlinear Iteration Method (HANIM) employed for

improved robustness

• Simulations performed steady - state

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Grid Generation

• Mixed - element grids generated

h y Cells (million)

using HeldenMesh

Coarse 1.00 1.00 35.3

TM • HeldenMesh r efinement factor,

Medium 0.44 0.44 94.1

h, varied to provide ~3x increase in

Fine 0.20 0.20 281.7

cells between grid levels

Coarse Medium Fine

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RESULTS

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Grid Refinement Study

• Grid refinement study performed for Cruise MFP and Clean

configurations at Re = 5 million, Mach = 0.8, and 𝛂 = 2 °

MAC

• Preliminary force and moment comparisons illustrated a shift in 𝛂

between the experiment and CFD

• CFD solutions lift - matched to experimental data point to provide

consistent comparison

0.6 0.6 EXP EXP 0.5 0.5 USM3D-ME USM3D-ME 0.4 0.4 0.3 0.3 C C L L 0.2 0.2 0.1 0.1 0.0 0.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0.015 0.018 0.021 0.024 0.027 0.030 C ! (deg) D

Clean Configuration, Re = 5 million, Mach = 0.8, Medium Grid

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Force and Moment Coefficients

0.0240

• All remaining results provided for

0.0239 EXP

Cruise MFP configuration

USM3D-ME 0.0238 0.0237

• C results illustrate successful lift -

L 0.0236

matching with experiment C

0.0235 D 0.0234

• Largest differences observed for C

m 0.0233 0.0232

comparisons

0.0231 0.0E+00 2.5E-06 5.0E-06 7.5E-06 1.0E-05

• Only 2 counts difference in C for

D - 2/3 N

medium and fine grids

0.085 0.358 0.080 0.356 EXP 0.075 USM3D-ME 0.354 EXP 0.070 0.352 USM3D-ME 0.065 0.350 C C 0.060 m 0.348 L 0.055 0.346 0.050 0.344 0.045 0.342 0.040 0.340 0.0E+00 2.5E-06 5.0E-06 7.5E-06 1.0E-05 0.0E+00 2.5E-06 5.0E-06 7.5E-06 1.0E-05 - 2/3 - 2/3 N N

Cruise MFP Configuration, Re = 5 million, Mach = 0.8, C = 0.349

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AIP Quantities

0.868

• Comparisons at AIP illustrate non -

EXP 0.863 USM3D-ME 0.858

monotonic trends with increasing

0.853

grid refinement

AIP 0.848 PR

• USM3D - ME predictions within 2%

0.843 0.838

of experimental data

0.833

• Small differences observed between

0.828 0.0E+00 2.5E-06 5.0E-06 7.5E-06 1.0E-05

medium and fine grids

- 2/3 N 0.620 3.60 EXP 0.615 3.55 USM3D-ME 0.610 3.50 0.605 avg,AIP (lbm/s) 0.600 M 3.45 AIP ṁ 0.595 EXP 3.40 0.590 USM3D-ME 0.585 3.35 0.0E+00 2.5E-06 5.0E-06 7.5E-06 1.0E-05 0.0E+00 2.5E-06 5.0E-06 7.5E-06 1.0E-05 - 2/3 - 2/3 N N

Cruise MFP Configuration, Re = 5 million, Mach = 0.8, C = 0.349

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Total Pressure at the AIP

0.94 0.92

• Predicted total pressure distributions

EXP 0.90 Coarse

at AIP in good agreement with

Medium 0.88 Fine t,∞ 0.86

experiment

/P 0.84 t,avg P

• M inor differences observed between

0.82 0.80

medium and fine grids

0.78 0 45 90 135 180 225 270 315 360

• Medium grid selected for NTF

Circumferential Location (deg)

condition sweep s

0.74 0.77 0.80 0.83 0.86 0.89 0.92 0.95 P /P t t ,

Experiment Fine Medium Coarse

Cruise MFP Configuration, Re = 5 million, Mach = 0.8, C = 0.349

0.74 0.77 0.80 0.83 0.86 0.89 0.92 0.95 0.74 0.77 0.80 0.83 0.86 0.89 0.92 0.95 MAC L 0.74 0.77 0.80 0.83 0.86 0.89 0.92 0.95 0.74 0.77 0.80 0.83 0.86 0.89 0.92 0.95 P /P P /P P /P P /P t t , t t , t t , t t , 2024 AIAA Aviation Conference 15 LANGLEY RESEARCH CENTER

NTF Condition Sweeps

Re (million) T ( ° F) Mach 𝛂 (deg)

MAC t

5 120 0.75, 0.80, 0.85 - 3 ° to 3 °

10 - 50 0.75, 0.80, 0.85 0.5 ° to 3 °

15 - 120 0.75, 0.80, 0.85 0.5 ° to 3 °

• Horizontal stabilizer removed for negative angles of attack to prevent

over - ranging balance

• NTF ran in cryogenic mode, utilizing Nitrogen, to achieve Re = 10 and

MAC

15 million

– USM3D - ME currently only allows for air mode

– All calculated quantities from the experiment (Mach number and mass flow rate)

assume air to provide consistent comparison with experiment

• Comparisons of Pressure Recovery, Mach, and Mass Flow Rate at the

AIP provided as a function of lift coefficient due to observed angle of

attack shift

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Cruise MFP, Re = 5 Million

MAC

0.883 0.670 0.658 0.646 0.866 0.634 0.622 0.849 0.610 AIP avg,AIP 0.598 PR M 0.586 0.832 0.574 0.562 0.815 0.550 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 C C L L 3.76 0.85 EXP, M = 0.75 3.69 0.83 EXP, M = 0.80 3.62 0.81 EXP, M = 0.85 PR (lbm/s) USM3D-ME, M = 0.75 0.79 3.55 AIP USM3D-ME, M = 0.80 ṁ 0.77 3.48 USM3D-ME, M = 0.85 0.75 3.41 0.0 0.1 0.2 0.3 0.4 0.5 0.6 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 C L C L

Cruise MFP Configuration, Re = 5 million

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Cruise MFP, Re = 10 Million

MAC

0.883 0.670 0.658 0.646 0.866 0.634 0.622 0.849 0.610 AIP 0.598 avg,AIP PR M 0.586 0.832 0.574 0.562 0.815 0.550 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 C C L L 5.61 0.85 EXP, M = 0.75 5.51 0.83 EXP, M = 0.80 5.41 0.81 EXP, M = 0.85 (lbm/s) PR USM3D-ME, M = 0.75 0.79 5.31 AIP USM3D-ME, M = 0.80 ṁ 0.77 5.21 USM3D-ME, M = 0.85 0.75 5.11 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 C L C L

Cruise MFP Configuration, Re = 10 million

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Cruise MFP, Re = 15 Million

MAC

0.670 0.883 0.658 0.646 0.866 0.634 0.622 0.610 0.849 AIP avg,AIP 0.598 PR M 0.586 0.832 0.574 0.562 0.550 0.815 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 C C L L 7.24 0.85 EXP, M = 0.75 7.10 0.83 EXP, M = 0.80 6.96 0.81 EXP, M = 0.85 (lbm/s) PR USM3D-ME, M = 0.75 0.79 6.82 AIP USM3D-ME, M = 0.80 ṁ 0.77 6.68 USM3D-ME, M = 0.85 0.75 6.54 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 C L C L

Cruise MFP Configuration, Re = 15 million

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SUMMARY AND

CONCLUSIONS

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Summary and Conclusions

• NTF wind tunnel test performed for CRM - TCT model to both investigate

the flow ingested by aft - mounted propulsor configuration and provide a

database to enable code validation

• Grid refinement study performed to assess impact of grid size

– Results show that grid convergence not achieved but only small differences observed

between two finest grid levels

– Medium grid selected as best tradeoff between accuracy and computational cost

• Condition sweeps illustrated tendency for USM3D - ME to underpredict

the pressure recovery at the AIP

– Pressure recovery differences propagated to Mach number and mass flow rate calculations at

Overview

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