[PPT] - Agenda Background/Motivation ARISP Rotor Icing Model PowerPoint Presentation

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Edward Brouwers

Graduate Research Assistant

THE EXPERIMENTAL INVESTIGATION OF

A ROTOR ICING MODEL WITH SHEDDING

Presentation to NASA Icing Branch April 8, 2010

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Agenda

Background/Motivation
ARISP Rotor Icing Model
Understanding AERTS
ARISP Correlations to AERTS Experiments
Conclusions & Recommendations for Future Work

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Motivation

Flight into Icing Conditions is Dangerous

– Reduced vehicle performance

Torque Rise
Stability & Control Issues
Excessive Vibration
Operational Limitations

– Simply avoid ice – Few aircraft have limited icing clearances – Fewer have IPS

Rotorcraft Compounding Factors

– Mission Urgency – Mission Profile – Vehicle Sensitivity to Ice – Shedding

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Rotor Icing Analysis

Test Facilities

– NRC Helicopter Spray Rig – McKinley Climatic Chamber – NASA IRT – Army HISS

NASA Photo C-1993-3962

Open Issues

– Oscillatory Airfoils – Tip Shape Effects

Modeling

– Complex problem – No comprehensive model – Lack of validation data

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Research Objectives

Develop Rotor Icing Model (ARISP)
Develop Icing Test Facility (AERTS)
Correlate ARISP Model to Experiments in AERTS Facility

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Agenda

Background/Motivation
ARISP Rotor Icing Model

– Program Design – Shedding/Performance Implementation – Validation

Understanding AERTS
ARISP Correlations to AERTS Experiments
Conclusions &

Recommendations for Future Work

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

AERTS Rotor Icing, Shedding and Performance (ARISP) Model

Objectives

– Aid AERTS Calibration – Uncover Icing Trends – Supplement NRA Activity

Simplified version of icing analysis effort
Primary Features

– Prediction of ice accretion on rotor systems – Predict performance degradation – Evaluates effects of ice shedding – Provide interface for ice protection system evaluation

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Program Setup

Overall Setup

– Analysis centered on the LEWis ICE Accretion Program (LEWICE)

Industry standard icing modeling software – extensively validated in IRT
ARISP uses LEWICE 3.0 – 2D version

– Pre and post processing written in MATLAB – Generally similar to work by:

Britton, “Development of an Analytical Method to Predict Helicopter Main Rotor

Performance in Icing Conditions, AIAA 92-0418

Miller et al, “Analytical Determination of Propeller Performance Degradation Due to Ice

Accretion” J. Aircraft Vol. 24 No. 11

Fortin and Perron, “Spinning Rotor Blade Tests in Icing Wind Tunnel” AIAA 2009-4260
Concept

– Quasi-2D Analysis

Rotor performance calculated in BEMT
Ice accretions calculated at each station

– Focused on hover due to AERTS Facility limitations

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Overall Program Flow

Loop Until Analysis Complete

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

LEWICE Interface

Program Inputs

– Rotor Geometry

Blade profile
Station properties (airfoil, material)
Analysis stations

– Icing Conditions

LWC function of rotor radius
Mono-dispersed droplet distribution assumed
Ramping of temperature/LWC
Software Coupling

– LEWICE time stepping logic is used to size number of analysis steps – Inputs for each station/timestep are created automatically

Airfoil Geometry – clean/iced airfoil
Icing Conditions – spanwise gradients in LWC etc

– Series of batch files connect MATLAB and LEWICE

LEWICE runs “inside” of MATLAB script
~0.5 seconds per LEWICE run
High fidelity test run requires about 10 minutes

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

ARISP BEMT Validation

Dry BEMT Module Comparison vs NASA CR 2275 Dry BEMT Module Comparison vs Prouty Tail Rotor

BEMT currently corrected for AERTS Chamber per NASA TM 86754
C81 Performance tables for NACA 0012, NACA 0015 included in ARISP

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

ARISP Ice Accretion Comparisons Model Scale

Model Scale – NASA TM 103712
Tests conducted in NASA IRT (1989)

– 6’ diameter NACA 0012 generic rotor – Ice tracings published at various rotor stations for many icing conditions – Rotor trimmed in ARISP model to match average station AoA

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Full Scale ARISP Ice Shape Validation

Full Scale – NASA CR 168332

– Tests conducted at Canadian NRC Helicopter Spray Rig with UH-1H – Results from Flight E Documented – Conditions

Temperature corrected from -19°C to -14°C
LWC = 0.7 gr/m3
MVD = 30 µm
Time = 3 min

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Ice Extent Calculations

Method of determining spanwise ice accretion

– Based upon static temperature and ram temperature rise – Assumes thermodynamic recovery factor per NASA CR 3910 – Model validated to CR 3910 and UH-1H HIFT Data Validation

) , ( M LWC f

Current Research

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Ice Accretion Comments

Overprediction of Ice at Rotor Tips

– Opposite of expectations – Seen in previous research

NASA TM 107312
Gent, “Further Studies of Helicopter Rotor Ice

Protection Accretion and Protection” Vertica Vol 11 Issue 3, 1987

– May be related to droplet bounce, centrifugal effects and LWC gradients – Shedding

2D nature of shedding analysis may miss shedding
f glaze ice horns

NASA TM 103712

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Performance Degradation

Modeling

– Primary metric is rotor torque

Dependent on sectional drag coefficients
Lift degradation small

– Empirically modeled based upon published correlations

Bragg’s and Flemming’s Correlations

currently included in ARISP

Implementation

– Dynamic database of sectional drag coefficients

Updated after each time step with ΔCd
If shedding occurs, clean airfoil

performance is used

Gray Bragg Flemming Temperature (°C) min

17.7
17.7
20.0

max

3.8
12.2

7.7 MVD (µm) min 11.3 7.0 11.0 max 19.0 19.0 50.0 LWC (gr/m3) min 0.39 0.50 0.24 max 2.00 1.86 3.80 Velocity (ft/sec) min 183.3 256.6 287.7 max 403.3 403.3 745.1 Icing Time (min) min 3.0 1.0 0.3 max 17.7 27.0 5.0

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Shedding Implementation

Centrifugal Force Net Aerodynamic Force (negligible) Ice Forces Section A-A

X Y Z

Shear Adhesion Force Cohesion Force Analysis Direction Ω A A Differential Ice Element

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Shedding Progression

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Ice Details

X Y Z

Centrifugal Force Ice Adhesion Area Impingement Limits Calculated from LEWICE Typical Ice Shape, assumed quasi 2D Ice Cross Sectional Area shi slow

Impingement Limit Tracker

– Furthest aft impingement limits selected for each station (updated each time step, reset after shedding event) – Glaze ice feathers

Cross Ice Area Summation

– Area calculated by LEWICE (integration of thickness) – Summed for each timestep, reset after shedding event

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

ARISP Model

Loop Until Analysis Complete

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Ice Properties

Ice Cohesive (Tensile) Strength

– Uses results from the work of Chu and Scavuzzo: “Tensile Properties of Impact Ices,” AIAA 92-0883

Ice Shear Adhesion Strength

– Currently taken from variety of sources:

Stallabrass and Price: “On the Adhesion of Ice

to Various Materials,” NRC Canada LR-350

Scavuzzo and Chu: “Structural Properties of

Impact Ices Accreted on Aircraft Structures,” NASA CR 179580

Reich: “Interface Influences Upon Ice

Adhesion to Airfoil Materials,” AIAA 94-0714

– Eventually calculated in the AERTS for each icing condition

Ice Density

– Macklin and Jones model included in ARISP model – All analysis presented uses Jones Model

Author Ice Density (kg/m3) Ashton 918 Macklin 900 Stallabrass 884 Jones 910 LEWICE 917

Ice Density T = -10°C, LWC = 1.5 gr/m3, MVD = 20 µm

Author/Date Method Aluminum Shear Adhesion Strength psi kPa Loughborough* 1946 Pull 81 558 Stallabrass and Price† 1962 Rotating Instrumented Beam 14 97 Itagaki† 1983 Rotating Rotor 4 - 23 27 - 157 Scavuzzo and Chu† 1987 Shear Window 13 - 42 90 - 290 Reich* 1994 Pull 130 896 PSU AERTS* Pull 76 526

Shear Adhesion Strength for Aluminum T = -11˚C

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Shear Adhesion Strength Calculation

Problem

– Shear adhesion strength is a function of icing condition – Data is characterized by significant scatter (± 35 %)

Variation due to test method – various mechanical methods
Variation due to test facility – limited velocity, ice transport
Approach

– Based upon work of Stallabrass and Price (NRC Canada LR-350, 1962)

Mount test coupons on instrumented beam at rotor tip
Monitor strain on beam to calculate shear adhesion strength

– Key Benefits

Test realistic icing conditions
Approach realistic rotorcraft tip speeds
Accrete ice and test in one facility

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Shedding Fixture Concept

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Implementation

Test Coupon Rotor (9’ diameter) Instrumented Beam Heated Fairing (shown transparent) Coupon Mounting Block Tailored strain field for instrumentation

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Implementation

Model of Instrumented Beam at Design Point 1200 rpm (565 ft/sec) Provision for de-ice heaters

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Beam Load (N) Voltage (V) Vo Lo LRPM VRPM LICE

Loading Line Equation determined by points (Vo,Lo) and (VRPM, LRPM)

VICE

Loading due to RPM Loading due to ice Extrapolated Loading Line Calculation Goal

Test Fixture Logic

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence 3.7 3.8 3.9 4 4.1 4.2 4.3 4.4 4.5 50 100 150 200 250 300 350 400 450

Voltage

RPM

400 Gain 500 Gain 400 Gain, + Mass 500 Gain, + Mass

500 gain 400 gain ΔV

y = -0.0003x2 + 0.0111x - 0.0003 R² = 0.9979

0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 0.05 0.00 1.00 2.00 3.00 4.00 5.00 6.00

Delta Voltage (V) Beam Load (kg)

500 Gain

Poly. (500 Gain)

Shedding Fixture

Shedding fixture is capable of sensing small ice accretions – good SNR

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Icing Shakedown Testing

Blade Anti-Ice Heater Locations Heated Side Fairings Previous testing ice bridging

Problem: Ice Bridging Solution: Heater Fairings Problem: Blade Icing Solution: Anti-Ice Heaters

5 W/in2 Heater (20 per blade)

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Icing Shakedown Tests (con’t)

Notch Ice Accretions Runback Ice Problem: Notch Icing Solution: Additional Heater 10 W/in2 heater

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Icing Shakedown Tests (con’t)

Notch Ice Accretions Runback Ice Problem: Notch Icing Solution: Additional Heater 10 W/in2 heater

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Sample Shear Adhesion Test Fixture Raw Data

Loading due to accreted ice VRPM Shedding Event @ t = 403 s Rotor Spool Down Icing cloud on

Note long test time. Chamber temperature may increase significantly

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Shedding Fixture Test Results

0.00 100.00 200.00 300.00 400.00 500.00 600.00 700.00 800.00 900.00 1000.00

30
25
20
15
10
5

Shear Adhesion Strength (kPa) Temperature ( C)

AERTS (Current Research) Loughenborough (1946) Stallabrass and Price (1962) Itagaki (1983) Scavuzzo and Chu (1987) Reich (1994)

LWC = 10 gr/m3 MVD = 40 µm

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

T = -10.0 °C LWC = 3.0 gr/m3 MVD = 40 µm t = 300 sec RPM = 800 Θ0 = 5°

Sample ARISP Outputs

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

T = -5.0 °C LWC = 3.0 gr/m3 MVD = 40 µm t = 300 sec RPM = 800 Θ0 = 5°

Sample ARISP Outputs

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Agenda

Background/Motivation
ARISP Rotor Icing Model
Understanding AERTS

– CFD Modeling – Sensitivity Studies

ARISP Correlations to AERTS Experiments
Conclusions & Recommendations for Future Work

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

CFD Modeling

Objective

– Understand complex flowfield in chamber (rotor in box) – Assist in particle trajectory analysis

Software: Solidworks Flow Simulation

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

600 RPM Velocity Contours

NACA 0015 Rotor 7.75’ diameter 600 RPM Θo = 2.5°

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

600 RPM Nozzle Flow Tubes

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

600 RPM 20 µm Trajectories

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Sensitivity Studies

Tip Vortex Effect

AERTS is a unique facility
Series of tests were run to explore

AERTS icing envelope

– Temperature – Droplet Size – Nozzle Settings – Rotor RPM – Collective Pitch

Limits established for facility
Crystalization

– Erosion of ice shapes significant issue – Problem corrected with ice screens and corrected nozzle settings T ≈ -10°C, LWC ≈ 1.3 – 1.6 gr/m3

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Agenda

Background/Motivation
ARISP Rotor Icing Model
Understanding AERTS
ARISP Correlations to AERTS Experiments

– General Observations – Ice Shape/Torque/Shedding Correlations

Conclusions & Recommendations for Future Work

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Test Rotor

Parameter Schweizer 269C Application PSU AERTS Application Units Radius 13.42 3.87 ft Chord 6.8 in Solidity 0.040 0.092

Tip Speed

662 200 – 608 ft/sec RPM 471 500 - 1500

Twist (linear)
8.7
2.1

degrees Airfoil NACA 0015

LE Material

2024-T3 Aluminum

Weight

~1.33 lb/ft

Painted stripes provide consistent measuring points. Each

stripe is 0.05R wide.

The blade leading edge is not painted to allow for shedding
analysis. Ice accretes directly to an 2024-T3 aluminum

surface. Blades donated by Schweizer Aircraft Blade grips donated by Olympic Tool and Machine Corporation

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Test Cases

Case Temperature MVD Corrected LWC Nozzle Config RPM Collective Time Shedding Shedding Station °C µm gr/m3 deg sec ? 24

10.75

25 2.0 5 Outer 500 2.5 180 N 25

10.50

25 1.6 5 Outer 600 2.5 180 N 26

10.85

35 1.2 5 Outer 600 2.5 180 N 27

10.50

35 2.3 5 Outer 600 2.5 180 N 28

15.60

15 2.0 5 Outer 600 2.5 180 N 29

5.10

35 6.6 5 Outer 180 2.5 180 N 31

5.80

35 3.0 5 Outer 600 2.5 215 Y 0.83 32

9.90

35 2.8 5 Outer 600 2.5 300 N 33

4.70

20 6.9 5 Outer 600 2.5 352 Y

0.77

34

6.50

35 3.7 5 Outer 600 2.5 272 Y

0.87

35

8.00

25 1.2 4 Outer 600 2.5 320 Y

0.83

36

5.00

25 1.3 4 Outer 600 2.5 427 Y

0.81

37

5.00

15 2.2 4 Outer 600 2.5 313 Y

0.75

38

3.00

25 1.3 4 Outer 600 2.5 304 Y

0.79

39

3.00

15 2.2 4 Outer 600 2.5 391 Y

0.82

40

14.20

15 1.2 3 Outer 600 2.5 180 N 41

12.00

15 0.9 3 Outer 600 2.5 180 N 43

8.60

15 1.2 3 Outer 600 2.5 144 Y 0.72 44

10.05

15 1.3 3 Outer 600 2.5 180 N Parameter Minimum Maximum Temperature (°C)

15.6
3.1

MVD (µm) 15 35 LWC (gr/m3) 0.9 6.5 Icing Time (s) 144 427

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Test Case Correlation to FAR Part 25/29 Appendix C Icing Envelope

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Typical Test Video

(.mov)

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Ice Accretion Results

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

LWC Calculation

Calculated Experimentally

– No dedicated sensor, calculation based upon stagnation ice thickness – Significant errors may be generated – ARISP Model must be run after experiment

Results

– General root to tip gradient due to CF and flowfield effects

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Case 44 Shapes

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Qualitative Shape Correlation

Case Station 0.6r 0.7r 0.8r 0.9r

24

Y

Y G

25

Y

G Y

26

Y

Y R

27

Y

Y Y

28

R

R R

29

Y

R R

31

G

G G

32

G

G G

33

R

R Y

34

Y

G G

35

G G Y Y

36

R R R R

37

G G Y Y

38

G G Y Y

39

G G G G

40

G G G G

41

G G Y Y

43

G G

44

G G G G

Red Case 29, 0.9r Yellow Case 24 0.9r Green Case 25, 0.8r

Best correlations at small particle size, low LWC

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Impingement Limits

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Torque Correlations

Torque Offset Calculation Case 31 Torque

Torque calibration runs were made to isolate rotor performance

– Removes influence of bearings and seals

Torque Correlations

– Shaft torque was monitored during all testing – Bragg’s correlations were used in all correlations

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Torque Correlations

Highest Temperatures

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Shedding

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Shedding Event Correlation

Shedding Station

LWC (gr/m3) indicated by each point

Shedding Time

LWC (gr/m3) indicated by each point

9 Test Cases Involved Shedding Events

– Most events involved a single blade – All shedding occurred as a single event – Significant imbalance required test stand to be shut down immediately due to high 1/rev loads

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Shedding Correlations

Ice Properties

– Cohesive Strength: Chu and Scavuzzo: “Tensile Properties of Impact Ices,” AIAA 92-0883 – Shear Adhesion: Reich “Interface Influences Upon Ice Adhesion to Airfoil Materials,” AIAA 94-0714

Correction Factor

– ARISP generally overpredicted accreted ice shapes

Ice mass was therefore lower, generating

errors in the shedding analysis

Tip runback unpredicted

– Uncorrected, the ARISP model predicted multiple shedding events,

ccurring earlier

– Correction factor derived from ice areas

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Shedding Corrections

Case Shedding Event AERTS ARISP No Corrections C ARISP

rrections

Time (s) %R Time (s) %R Time (s) %R 31 1 215 0.82 130 0.82 160 0.81 33 1 352 0.77 100 0.93 150 0.92 2 210 0.64 300 0.72 3 320 0.93 34 1 272 0.87 70 0.97 120 0.90 2 150 0.73 220 0.71 3 210 0.97 35 1 320 0.83 85 0.99 123 0.99 2 107 0.92 151 0.84 3 160 0.76 268 0.69 4 245 0.99 5 266 0.92 6 309 0.61 36 1 427 0.81 170 0.91 2 270 0.68 37 1 313 0.75 94 0.88 135 0.94 2 167 0.69 188 0.72 3 261 0.88 38 1 304 0.79 91 0.95 101 0.97 2 132 0.76 132 0.88 3 203 0.95 203 0.73 4 243 0.66 39 1 391 0.82 183 0.95 248 0.97 2 261 0.80 300 0.84 43 1 144 0.72 125 0.96 2 3 4

Case 31, Corrected Case 31, Uncorrected

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Agenda

Background/Motivation
ARISP Rotor Icing Model
Understanding AERTS
ARISP Correlations to AERTS Experiments
Conclusions & Recommendations for Future Work

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Conclusions

ARISP Model

– Demonstrated the ability of model based upon LEWICE to predict ice accretions

n rotor blades

– Additional features integrated into model include torque degradation and shedding – Model compared to published ice shapes, model scale & full scale

AERTS Facility

– Basic understanding of the chamber flowfield and particle trajectories

– Limitations established, especially for airfoil shapes

Experimental Correlations

– Shape: Generally good, overpredicted accretions at tip – Impingement Limits: Within 20% of predicted values – Torque: Using Bragg’s correlations, most test cases were within 20% of predicted values – Shedding: Further work required – Test conditions need to be better quantified for proper modeling

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Future Work

ARISP

– Ice Accretion

CF effects on ice accretion - LWC variation
Tip flowfield quantification

– Shedding

Shear adhesion strength test points
Tensile strength validation
More shedding test points
Non-square tip shapes
Trajectory analysis of shed ice
AERTS

– Icing Condition Monitoring

Temperature Control – current system limited
MVD Sensor – currently not measured
LWC Sensor – currently calculated experimentally

– Blades

Improved blade tracking/balance system

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Thank You Sponsors/Donors Questions?

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

Backup

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

800 RPM Velocity Contours

Nozzle Rings

NACA 0015 Rotor 7.75’ diameter 800 RPM Θo = 2.5°

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

1000 RPM Velocity Contours

Nozzle Rings

NACA 0015 Rotor 7.75’ diameter 1000 RPM Θo = 2.5°

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence

800 RPM 20 µm Trajectories

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Adverse Environment Rotor Test Stand The Vertical Lift Research Center of Excellence