COMPUTATIONAL INVESTIGATION OF ROTARY ENGINE HOMOGENEOUS CHARGE COMPRESSION IGNITION FEASIBILITY A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Engineering By Michael Irvin Resor B.S., Wright State University, 2012 2014 Wright State University WRIGHT STATE UNIVERSITY GRADUATE SCHOOL December 9, 2014 I HEREBY RECOMMEND THAT THE THESIS PREPARED UNDER MY SUPERVISION BY Michael Irvin Resor ENTITLED Computational Investigation of Rotary Engine Homogeneous Charge Compression Ignition Feasibility BE ACCEPTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF Master of Science in Engineering. Committee of George Huang, Ph.D. Final Examination Thesis Director Haibo Dong, Ph.D. George Huang, Ph.D. Co-Advisor Chair Department of Mechanical and Materials Engineering George Huang, Ph.D. College of Engineering and Computer Science Greg Minkiewicz, Ph.D. Scott Thomas, Ph.D. Zifeng Yang, Ph.D. Robert E. W. Fyffe, Ph.D. Vice President for Research and Dean of the Graduate School Abstract Resor, Michael Irvin. M.S. Egr., Department of Mechanical and Materials Engineering, Wright State University, 2014. Computational Investigation of Rotary Engine Homogeneous Charge Compression Ignition Feasibility. The Air Force Research Laboratory (AFRL) has been investigating the heavy fuel conversion of small scale Unmanned Aerial Vehicles (UAV). One particular platform is the Army Shadow 200, powered by a UEL Wankel rotary engine. The rotary engine historically is a proven multi-fuel capable engine when operating on spark ignition however, little research into advanced more efficient compression concepts have been investigated. A computational fluid dynamics model has been created to investigate the feasibility of a Homogeneous Charge Compression Ignition (HCCI) rotary engine. This research evaluates the effects, rotor radius to crankshaft eccentricity ratio, known as K factor, equivalence ratio, and engine speed and how they affect the response of horsepower, maximum temperature, and peak pressure to determine the feasibility of HCCI operation. The results show that the advanced HCCI strategy is promising to significantly improve efficiency of the rotary engine. iii TABLE OF CONTENTS Chapter 1: Introduction ................................................................................................................... 1 Background .................................................................................................................................. 1 Rotary Engine ........................................................................................................................... 1 High Temperature Combustion (SI and CI) .............................................................................. 3 Low Temperature Combustion (HCCI/PCCI) ............................................................................ 5 Research Objective ...................................................................................................................... 7 Methodology ................................................................................................................................ 8 Literature Review ......................................................................................................................... 9 Thesis Outline ............................................................................................................................ 11 Chapter 2: Validation ..................................................................................................................... 12 Z19DTH - Piston Engine .............................................................................................................. 12 Modeling and Meshing .......................................................................................................... 13 Solver Models and Numerical Settings ...................................................................................... 15 Combustion ............................................................................................................................ 16 Turbulence and Wall Heat Flux .............................................................................................. 17 Results ........................................................................................................................................ 17 Chapter 3: Rotary Engine Model .................................................................................................... 19 iv Modeling and Meshing .......................................................................................................... 19 Boundary and Initial Conditions ............................................................................................. 22 Solver Settings ........................................................................................................................ 24 Chapter 4: Parametric Study on LTC Performance ........................................................................ 26 Rotary Homogeneous Charge Compression Ignition (HCCI) ...................................................... 26 Parameters ............................................................................................................................. 26 Responses .............................................................................................................................. 27 Held Constant Factors ............................................................................................................ 28 Results of 33 Factorial............................................................................................................. 28 Best Fit Case Results from 33 Factorial................................................................................... 40 Equivalence Ratio Single Factor Fitting .................................................................................. 41 Best Fit Case Equivalence Ratio Single Factor Fitting ............................................................ 44 Chapter 5: Conclusions .................................................................................................................. 48 Chapter 6: Future Work ................................................................................................................. 50 References ..................................................................................................................................... 52 v LIST OF FIGURES Figure 1 Rolls Royce Diesel Engine [1] ............................................................................................. 2 Figure 2 Rotary engines of different K factors [2] ............................................................................ 3 Figure 3 The four diesel combustion phases [4] .............................................................................. 5 Figure 4 Combustion Strategies on Φ - T Diagram [7] ..................................................................... 7 Figure 5 2D Piston Pocket Cross Section ........................................................................................ 14 Figure 6 Solidworks Sector Geometry at Intake Port Close ........................................................... 14 Figure 7 Mesh Sector Geometry at Intake Port Close ................................................................... 14 Figure 8 Z19DTH CFD Model Wall Conditions ................................................................................ 15 Figure 9 Graphical Representation of PDF [23] ............................................................................. 16 Figure 10 Pressure Trace of Z19DTH Validation ............................................................................ 18 Figure 11 Circular arc approximation of Rotor Flank ..................................................................... 20 Figure 12 Rotary Engine Geometries and Meshes ......................................................................... 21 Figure 13 Epitrochoidal Path .......................................................................................................... 22 Figure 14 Rotary Engine Thermal Boundary Conditions+ ............................................................. 22 Figure 15 Design Table ................................................................................................................... 29 Figure 16 Summary of fit and ANOVA table for Pressure Rise Rate .............................................. 30 Figure 17 Summary of fit and ANOVA table for Maximum Temperature ..................................... 30 Figure 18 Summary of fit and ANOVA table for Horsepower ........................................................ 31 Figure 19 Actual by Predicted Plots ............................................................................................... 31 Figure 20 Parameter Estimates ...................................................................................................... 32 vi Figure 21 Plots of Residuals of Pressure Rise Rate plotted verses factors .................................... 33 Figure 22 Plots of Residuals of Max Temperature plotted verses factors ..................................... 34 Figure 23 Plots of Residuals of Horsepower plotted verses factors .............................................. 35 Figure 24 2000 RPM Profiler Plot with Desirability ....................................................................... 36 Figure 25 4000 RPM Profiler