Task A-1.13: Experimental Measurement of Ice Accretion and Shedding of Rotating Airfoils

Transcription

1 Task A-1.13: Experimental Measurement of Ice Accretion and Shedding of Rotating Airfoils Dr. Jose L Palacios Research Associate jlp324@psu.edu Yiqiang Han Research Assistant ARMY Program Review April 7,

2 Outline Background and Motivation Research Objectives Technical Approach Facility Description and Limits Facility Sensitivity Studies LWC Ice Shape Correlation to IRT/USAF Tests Ice Shedding Rig Summary 2

3 Background and Motivation Ultimate goal: All Weather Rotorcraft Rotorcraft qualification through full-scale tests is challenging and expensive Uncertainties in flight test data (conditions are difficult to control and measure) Need for well-validated analytical tools There are few test facilities that can accommodate rotating icing tests Ice accretion, shedding and performance degradation data collection required Current 6.2 NRTC project: High Fidelity Icing Analysis and Validation for Rotors Bell/Boeing/Sikorsky/NASA effort CFD Tool development Penn State/Bell (NASA-NRA) Testing In NASA IRT starting 2011 Goal: validate analytical tools for the prediction of rotor and fuselage ice accretion, ice shedding from a rotating/oscillating blade, deice and anti-ice system performance including transient heat transfer, and performance impact due to ice accretion. Limited open access to ice shape database accreted during rotation

4 Research Objectives Finalize Construction of a Rig: Adverse Environment Rotor Tests Stand - AERTS Determine Capability and Limitations of the facility Facility LWC Calibration Generate Ice Shape Database (NACA 0015) Generate Ice Shedding Database (Al., SS, TI, Ni) 4

5 Proposal Comments High level of risk involved in the development of this facility. To assist code development or icing physics studies, need to quantify and mitigate the uncertainties in the icing cloud. Identify facility limitations, and determine facility unknowns (LWC) Develop an alternative airfoil section beyond the current elliptical section 1-in Cylinder and 3.75-in chord NACA 0015 currently used; Next test plan has been targeted at the NACA 0012 for calibration Tighten up the objectives and provide additional costs and items needed for calibration. Need a cost estimate for PIV and LWC needs, plus a risk reduction path which assumes a realistic level of funding. The objective has been revised (oscillation accretion postponed) and attention will be intensively paid on the facility validation, accretion correlation, analysis of coupled parameter impact and scaling method for realistic level of future research.

6 Outline Background and Motivation Research Objectives Technical Approach Facility Description and Limits Facility Sensitivity Studies LWC Ice Shape Correlation to IRT/USAF Tests Ice Shedding Rig Summary 6

7 AERTS Facility New Features Slip Ring Weather Station 9 ft Creation of new capabilities at the AERTS - Low cost rotor icing facility - Collective and lateral cyclic rotor control 9 ft. blades - Ice shape measurements system Bell Housing w/ 6 Axis Load Cell Collective Actuator

8 Environment Control Limitations LWC Controlled by MVD, nozzle configuration and temperature NASA standard nozzles, controlled with feedback control loops for constant water and air pressure Flexible nozzle control (0 to 15 nozzles) Testing has shown that chamber saturation occurs at P (water - air PSI) of >45 Psi This promotes crystallization of water particles Crystals erode ice shapes, generating spear-like geometries Reduction of operational nozzles/water flow rate mitigates the issue View From Tip NACA 0012 Samples of Eroded Ice Shapes 8

9 Median Volume Diameter, µm Air Pressure psig 10 AERTS LIMIT W ater Pressure - Air Pressure, psid NASA Standard Nozzle Adjustable Nozzle Control total 15 Nozzles Facility Ceiling View

10 Icing Experiments Performed at AERTS Eroded Ice Shape 25 Psi Air, 25 MVD, 500 RPM 30 Psi Air, 25 MVD, 500 RPM High number of nozzles, High airline Ice shape Erosion Tsao, J., Kreeger, R., AIAA Water droplet: Saturation, Crystallization Collection Screen for Crystal Eroded spear ice shape Mitigation 10

11 Temperature Limitation Temperature Chamber cooled by convection fans Fans must be shut down during operation to avoid ice accretion Currently, it limits the capability to maintain a desired temperature within 1 C to 3.5 minutes, as warm air, water and kinetic friction of the rotor increase the temperature in the chamber DURIP Requested to install conduction cooling lines to maintain temperature during testing

12 Icing Test Capability: MVD/LWC MVD: Calculated from NASA calibration tables (10 to 100 µm) - Not directly or indirectly measured during testing LWC: Changing with water cloud, coupled with: MVD, Local Velocity, Aerodynamics (circulation at the tip - ), etc., temperature Also, sensors not applicable: - LWC sensors required a minimum velocity component - Rotation of sensors is not possible LWC MUST BE EXPERIMENTALLY DETERMINED 12

13 LWC Calculation Code A LWC tracing back method based on experimental ice thickness was developed Validation based on experimental data from: 40 cases for airfoil from Evaluation and Validation of the Messinger Freezing Fraction, Anderson D., and Tsao, J., NASA/CR , AIAA , 14 cases for cylinder from Evaluation of Constant-Weber-Number Scaling for Icing Tests, Anderson, David N., AIAA and NASA TM NASA confirms LWC values in the IRT by checking ice thickness on grids In our case, we measure ice thickness, and calculate freezing fraction and corresponding LWC 13

14 14

15 LWC Calculation Code Validation From experimental LWC and ice thickness presented in literature: determine if code can predict LWC from ice thickness Evaluation and Validation of the Messinger Freezing Fraction, Anderson D., and Tsao, J., NASA/CR Evaluation of Constant-Weber- Number Scaling for Icing Tests, Anderson, David N., AIAA and NASA TM

16 Code Validation: Result Comparison Code Prediction Evaluation and Validation of the Messinger Freezing Fraction, Anderson D., and Tsao, J., NASA/CR , AIAA , Some of the data shows Discrepancy Evaluation of Constant-Weber- Number Scaling for Icing Tests, Anderson, David N., AIAA and NASA TM

17 Uncertainty Analysis and Measurement Tolerance 0.08 (45%) difference in freezing fraction 0.8 (200%) difference in LWC AERTS Experiments inch difference in ice thickness 0.43g/m 3 difference in LWC

18 AERTS LWC Sensitivity Studies CALIBRATION CONDITIONS Total: 21 Test Cases RPM MVD (µm) Temperature ( C) Airline (psi) Tip speed 180 ft/sec Bottom View Rotor with Accreted Ice 18

19 Icing Experiments Performed at AERTS Thickness VS. Temperature 500 RPM, 25 Psi Air, 25 MVD, 3 min. Ice Thickness (in.) Rotor Span (r/r) C, LWC, 2.55 g/m C, LWC 2.35 g/m C, LWC 2.29 g/m 3

20 -15 0 C, LWC, 2.55 g/m C, LWC 2.35 g/m C, LWC 2.29 g/m 3

21 Icing Experiments Performed at AERTS Thickness VS. Temperature Thickness VS. MVD 500 RPM, 25 Psi Air, -15 Deg. C Ice Thickness (in.) MVD 30 MVD Linear (30 MVD) Linear (20 MVD) LWC = 2.4 gr/m 3 LWC = 2.2 gr/m Rotor Span (r/r)

22 25 Air line, 25 MVD, -5 Deg C. Ice Thickness (in.) LWC 3 gr/m 3 LWC 2.4 gr/m RPM 500 RPM Span Location (r/r) Thickness VS. RPM

23 Outline Background and Motivation Research Objectives Technical Approach Facility Description and Limits Facility Sensitivity Studies LWC Ice Shape Correlation to IRT/USAF Tests Ice Shedding Rig Summary 23

24 Icing Experiments Performed at AERTS Reproduction of Literature Ice shapes Y Dimension (in.) Reference Cylinder Experimental 27 MVD 490 RPM 0.91 r/r 59.2 m/sec C 1 in Tube X Dimension (in.) Ref: Anderson, D., Rime-, Mixed-, and Glaze-Ice Evaluations of Three Scaling Laws, NASA Technical Memorandum , AIAA , AIAA 32nd Aerospace Sciences Meeting and Exhibit, Reno, Nevada January 10-13, 1994.

25 Results 25 MVD 510 RPM r/r 58 m/sec C Ref: Anderson, D., Rime-, Mixed-, and Glaze-Ice Evaluations of Three Scaling 25 Laws, NASA Technical Memorandum , AIAA , AIAA 32nd Aerospace Sciences Meeting and Exhibit, Reno, Nevada January 10-13, 1994.

26 Results Ref: Ruff, G., Analysis and Verification of the Icing Scaling Equations, Air force Technical Report AEDC-TR-85-30, November

27 Results Ref: Ruff, G., Analysis and Verification of the Icing Scaling Equations, Air force Technical Report AEDC-TR-85-30, November 1985

28 Summary Ice Shape Validation Results It is believed that increases of temperature during testing beyond the desired comparison value are the main cause for shape deviations Ref: Ruff, G., Analysis and Verification of the Icing Scaling Equations, Air force Technical Report AEDC-TR-85-30, 28November 1985

29 Outline Background and Motivation Research Objectives Technical Approach Facility Description and Limits Facility Sensitivity Studies LWC Ice Shape Correlation to IRT/Airforce Tests Ice Shedding Rig Summary 29

30 Shedding Rotor Ref: Stallabrass, J., Price., R., On the Adhesion of Ice to Various Materials ft. Expected Behavior Strain Gauge Location Design by Ed Brouwers Construction/Testing Jose Palacios

31 Ice Shedding Rotor Post Shedding Photo

32 Sample Result Voltage Amplitude (V) RPM 0 RPM Icing Cloud ON Rotor OFF Shedding Time (Sec.)

33 Conclusions Facility construction finalized Capability to spin up to 9 ft. diameter rotors Limitations of facility identified Capability of performing desired icing tests in AERTS confirmed Generally satisfying correlation of experimental ice shape comparisons Correlations between IRT and AERTS stagnation ice thicknesses are excellent, with less than 2% discrepancy between tests Impingement limits deviated at the AERTS facility by increases of up to 16% of stagnation thickness It is believed that increases of temperature during testing beyond the desired comparison value are the main cause for these discrepancies

34 Future Work Calibration table, complete database Continue ice shape correlations Airfoils Investigate circulation and CF effects unique to AERTS Implement ice shape laser measuring system Test stability and repeatability Start data base creation (NACA 0015, shedding) 34

35 AERTS LAB Funding Motor Freezer DURIP AERTS Construction Icing Nozzles Huntsville, AL Glenn CF Rig QH-50 Hub PIV for Rotor and MVD Measurement DURIP Laser LWC DURIP PSU MVD, LWC Measurement & Cooling System DURIP? 35

36 External Interactions NASA (Eric Kreeger) Task Monitor AATD (Dr. Louis Centolanza, Nelson Ciron) Boeing (Andy Peterson) Goodrich (Galdemir Botura) Papers Palacios, J., Brouwers, E, Han, Y, Smith, E., ADVERSE ENVIRONMENT ROTOR TEST STAND CALIBRATION PROCEDURES AND ICE SHAPE CORRELATION 2010 AHS Brouwers, E., Palacios, J., Smith, E., Peterson, A., THE EXPERIMENTAL INVESTIGATION OF A ROTOR HOVER ICING MODEL WITH SHEDDING 2010 AHS, Litchten Competition Paper, 2010 NASA AHS Intern Award Winner Glaze Ice (60 µm) 36

37 Questions? 37