The Effects of Pressure on Particle Deposition in an Impinging Flow THESIS Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Craig Aaron Sacco Graduate Program in Aeronautical and Astronautical Engineering The Ohio State University 2016 Master's Examination Committee: Jeffrey Bons, Advisor Michael Dunn Copyrighted by Craig Aaron Sacco 2016 Abstract The High Pressure Deposition Test Facility was developed at The Ohio State University Aerospace Research Lab for the use of exploring particle deposition in turbomachinery- related applications such as impingement and film cooling. A number of related studies have been conducted at atmospheric pressure; however, particulate that enters the cooling air in an aero engine will be subjected to flows at much higher absolute pressures, which is determined by the pressure ratio of the compressor. Fluid density increases proportionally to pressure if subjected to a constant temperature. As density changes, so does Reynolds number, and thus the mechanisms that drive deposition are altered. A series of deposition tests has been conducted in an impingement cooling-representative set up for several elevated pressures from 0 to 200 psig and for three temperatures, 70, 450 and 850F. Results are presented in the form of topography maps of surfaces with deposition, linear traces of deposit peaks, volumes of deposited material, and post-test photos of deposition. It is found that deposit volumes decrease linearly with increasing pressure, and increase non-linearly with temperature. Additionally, computational fluid dynamics was utilized to visualize the flow in the experimental set up in an effort to understand the flow physics that control deposition at test conditions. CFD was also used to investigate the effect of pressure beyond the current experimental capabilities. ii Acknowledgments I would like to acknowledge my family and friends for always being supportive and a source of inspiration. I would also like to acknowledge my advisor, Dr. Jeffrey Bons, for being a patient and encouraging mentor. Lastly, I acknowledge my friend and colleague, Robin Prenter, for providing endless support and patience. iii Vita June 2009 .......................................................West Branch High School May 2014 .......................................................B.S. Aerospace Engineering, The Ohio State University August 2014 to present .................................Graduate Research Associate, Department of Mechanical and Aerospace Engineering, The Ohio State University Fields of Study Major Field: Aeronautical and Astronautical Engineering iv Table of Contents Abstract ............................................................................................................................... ii Acknowledgments.............................................................................................................. iii Vita ..................................................................................................................................... iv List of Tables .................................................................................................................... vii List of Figures .................................................................................................................. viii Nomenclature ..................................................................................................................... xi Chapter 1: Introduction and Background ........................................................................... 1 Chapter 2: Experimental Set-up .......................................................................................... 9 2.1 Test Apparatus........................................................................................................... 9 2.2 Measurement Techniques ........................................................................................ 14 2.3 Test Conditions ....................................................................................................... 18 2.4 Test Procedure ......................................................................................................... 19 Chapter 3: Computational Set-up...................................................................................... 21 3.1 Computational Domain and Boundary Conditions ................................................. 22 3.2 Mesh Generation ..................................................................................................... 23 v Chapter 4: Experimental Results ...................................................................................... 26 4.1 450F Air Flow ......................................................................................................... 26 4.2 850F Air Flow ......................................................................................................... 41 4.3 Volume and Height of Deposit for 450F and 850F ................................................. 60 4.4 Ambient Temperature Air Flow .............................................................................. 63 Chapter 5: Computational Results .................................................................................... 68 Chapter 6: Conclusions ..................................................................................................... 79 References ......................................................................................................................... 83 vi List of Tables Table 2.1. Matrix of Test conditions ................................................................................. 19 Table 3.1. Boundary conditions for CFD simulations ...................................................... 22 Table 3.2. Mesh cell counts .............................................................................................. 24 vii List of Figures Figure 1.1: Satellite image of global particular concentrations [1] .................................... 2 Figure 1.2. Damage to high-pressure turbine leading edge ................................................ 4 Figure 1.3. Flow regions of an impinging jet...................................................................... 6 Figure 1.4. Drag on a particle vs. Rep ................................................................................. 8 Figure 2.1. Schematic of test aparatus .............................................................................. 10 Figure 2.2. Operation map ................................................................................................ 12 Figure 2.3. Impingement plate schematic with periodic edge spacers (dotted lines) ....... 13 Figure 2.4. Test fixture with measurement locations (left), and side view of impingement/impact plate assembly (right) ........................................................................................................................................... 13 Figure 2.5. Approximate area of optical scan on test plate .............................................. 16 Figure 2.6. Example of scan linear trace and grid ............................................................ 17 Figure 3.1. Computational domain ................................................................................... 23 Figure 3.2. Mesh for a single hole .................................................................................... 24 Figure 3.3. Subtraction of wall shear for medium and fine grid ....................................... 25 Figure 4.1. Photos of dust deposition for 5 pressures at 450F air flow ........................... 28 Figure 4.2. Topography map scan results for (a) 0 psig, (b) 50 psig, (c) 100 psig, (d) 150 psig, and (e) 200 psig for 450F air flow viii ........................................................................................................................................... 31 Figure 4.3: Linear peak traces for (a) 0 psig, (b) 50 psig, (c) 100 psig, (d) 150 psig, and (e) 200 psig at 450F air flow ........................................................................................................................................... 34 Figure 4.4. 450F trace average compilation for all pressures .......................................... 37 Figure 4.5. Downstream side of plate for all pressures.................................................... 40 Figure 4.6. Photos of dust deposition for 5 pressures at 850F air flow ........................... 42 Figure 4.7. Comparison of target plates at 0 and 50 psig ................................................ 44 Figure 4.8: Topography map scan results for (a) 0 psig, (b) 50 psig, (c) 100 psig, (d) 150 psig, and (e) 200 psig at 850F air flow ........................................................................................................................................... 45 Figure 4.9: Linear peak traces for (a) 0 psig, (b) 50 psig, (c) 100 psig, (d) 150 psig, and (e) 200 psig at 850F air flow ........................................................................................................................................... 50 Figure 4.10. 850F compilation of traces for all pressures at 850F air flow ...................... 53 Figure 4.11. Close-up of Jets 3 and 4 deposit cones for 850 F ......................................... 54 Figure 4.12. Compilation of linear traces for all test cases at 450 and 850F .................... 56 Figure 4.13. Close-up of Jets