This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Quantification of Windage and Vibrational Losses in Flexure Springs of a One kW Two-Stroke Free Piston Linear Engine Alternator
ISSN: 0148-7191, e-ISSN: 2688-3627
Published April 02, 2019 by SAE International in United States
This content contains downloadable datasetsAnnotation ability available
Methods to quantify the energy losses within linear motion devices that included flexural springs as the main suspension component were investigated. The methods were applied to a two-stroke free-piston linear engine alternator (LEA) as a case study that incorporated flexure springs to add stiffness to the mass-spring system. Use of flexure springs is an enabling mechanism for improving the efficiency and lifespan in linear applications e.g. linear engines and generators, cryocoolers, and linear Stirling engines. The energy loss due to vibrations and windage effects of flexure springs in a free piston LEA was investigated to quantify possible energy losses. A transient finite element solver was used to determine the effects of higher modes of vibration frequencies of the flexure arms at an operational frequency of 65 Hz. Also, a computational fluid dynamics (CFD) solver was used to determine the effects of drag force on the moving surfaces of flexures at high frequencies. A parametric study was performed to understand the effects of geometrical and operational parameters including the diameter of flexures, gap width between flexure arms, stroke length, and frequency of oscillation on the drag force coefficient on the flexure surfaces. The numerical results were compared to experimental results obtained from damping tests and steady-state tests in a vacuum chamber. Modeled results were in good agreement with experiments and showed between 30 to 40 Watts of mechanical energy loss at 65 Hz in the 1 kW LEA design including windage and vibrational losses. It was also found that windage losses contributed to between 10-15% of the total mechanical losses. Also, damping tests in a vacuum chamber showed that in the absence of windage and acoustic losses between 30-35% of total input energy was lost due to structural and frictional damping. Measuring the amplitude of damped vibrations the damping ratio was calculated to be ζ=0.003.
- Nima Zamani Meymian - West Virginia University
- Nigel Clark - West Virginia University
- Jayaram Subramanian - West Virginia University
- Gregory Heiskell - West Virginia University
- Derek Johnson - West Virginia University
- Fereshteh Mahmudzadeh - West Virginia University
- Mahdi Darzi - West Virginia University
- Terence Musho - West Virginia University
- Parviz Famouri - West Virginia University
CitationZamani Meymian, N., Clark, N., Subramanian, J., Heiskell, G. et al., "Quantification of Windage and Vibrational Losses in Flexure Springs of a One kW Two-Stroke Free Piston Linear Engine Alternator," SAE Technical Paper 2019-01-0816, 2019, https://doi.org/10.4271/2019-01-0816.
Data Sets - Support Documents
|[Unnamed Dataset 1]|
- Wang, K., Sanders, S., Dubey, A., Choo, F. et al., “Stirling Cycle Engines for Recovering Low and Moderate Temperature Heat: A Review,” Renewable and Sustainable Energy, 62, Sep. 2016, 89-108.
- Woo, Y. and Lee, Y., “Free Piston Engine Generator: Technology Review and an Experimental Evaluation with Hydrogen Fuel,” International Journal of Automotive Technology 15(2):229-235, 2014.
- Liang, K., “A Review of Linear Compressors for Refrigeration,” International Journal of Refrigeration 84, 2017, doi:10.1016/j.ijrefrig.2017.08.015.
- Subramanian, J., Heiskell, G., Mahmudzadeh, F., and Famouri, P., “Study of Radial and Axial Magnets for Linear Alternator - Free Piston Engine System,” in 2017 North American Power Symposium (NAPS), Morgantown, WV, 2017, 1-6.
- Bade, M., Clark, N., Robinson, M., and Famouri, P., “Parametric Investigation of Combustion and Heat Transfer Characteristics of Oscillating Linear Engine Alternator,” Journal of Combustion, 2018, doi:10.1155/2018/2907572.
- Rawlings, R. and Miskimins, S., “Flexure Springs Applied to Low-Cost Linear Drive Cryocoolers,” Proceedings of SPIE 4130:406-412, 2000.
- Qiu, S., Peterson, A., and Augenblick, J., “Flexure Design and Testing for STC Stirling Convertors,” in 1st International Energy Conversion Engineering Conference (IECEC), doi:10.2514/6.2003-6040.
- Zamani, N., Clark, N., Musho, T., Darzi, M. et al., “An Optimization Method for Flexural Bearing Design for High-Stroke High-Frequency Applications,” Cryogenics 95:82-94, 2018, doi:10.1016/j.cryogenics.2018.09.008.
- Chen, N., Chen, X., Wu, Y., Yang, C. et al., “Spiral Profile Design and Parameter Analysis of Flexure Spring,” Cryogenic 46:409-419, 2006, doi:10.1016/j.cryogenics.2005.12.009.
- Al-Otaibi, Z. and Jack, A., “Spiral Flexure Springs in Single Phase Linear-Resonant Motors,” in 42nd International Universities Power Engineering Conference, 2007, doi:10.1109/UPEC.2007.4468943.
- Khot, M. and Gawali, B., “Finite Element Analysis and Optimization of Flexure Bearing for Linear Motor Compressor,” Physics Procedia 67:379-385, 2015, doi:10.1016/j.phpro.2015.06.044.
- Gaunkar, A., Goddenhenrich, T., and Heiden, C., “Finite Element Analysis and Testing of Flexure Bearing Elements,” Cryogenic 36(5):359-364, 1996.
- Lee, C. and Pan, R., “Flexure Bearing Analysis Procedures and Design Charts,” Cryocoolers 9:413-420, 1997.
- Johnson, D., Darzi, M., Ulishney, C., Bade, M. et al., “Methods to Improve Combustion Stability, Efficiency, and Power Density of a Small, Port-Injected, Spark-Ignited, Two-Stroke Natural Gas Engine,” in ASME, Internal Combustion Engine Division Fall Technical Conference, 2: Emissions Control Systems; Instrumentation, Controls, and Hybrids; Numerical Simulation; Engine Design and Mechanical Development, V002T07A008, doi:10.1115/ICEF2017-3557.
- Darzi, M., Johnson, D., Zamani, N., Ulishney, C. et al., “Baseline Evaluation of Ignition Timing and Compression Ratio Configurations on Efficiency and Combustion Stability of a Small-Bore, Two-Stroke, Natural Gas Engine,” in ASME IMECE, Tampa, FL, 2017.
- Darzi, M., Johnson, D., Ulishney, C., Bade, R.M.B. et al., “Quantification of Energy Pathways and Gas Exchange of a Small Port Injection SI Two-Stroke Natural Gas Engine Operating on Different Exhaust Configurations,” SAE Technical Paper 2018-01-1278, 2018, doi:10.4271/2018-01-1278.
- Darzi, M., Johnson, D., Bade, R.M.B., Ulishney, C. et al., “Continuously Varying Exhaust Outlet Diameter to Improve Efficiency and Emissions of a Small SI Natural Gas Two-Stroke Engine by Internal EGR,” SAE Technical Paper 2018-01-0985, 2018, doi:10.4271/2018-01-0985.
- Javaheri, A., Esfahanian, V., Salavati-Zadeh, A., and Darzi, M., “Energetic and Exergetic Analyses of a Variable Compression Ratio Spark Ignition Gas Engine,” Energy Conversion and Management 88:739-748, 2014, doi:10.1016/j.enconman.2014.09.009.
- Camara, J., Power Reference Manual (Professional Publication Inc., 2010). ISBN:978-1-59126-162-9.
- Dehkordi, B., Fallah, S., and Niazmand, A., “Investigation of Harmonic Instability of Laminar Fluid Flow Past 2D Rectangular Cross Sections with 0.5-4 Aspect Ratios,” Journal of Mechanical Engineering Science 228(5):828-839, 2014, doi:10.1177/0954406213491906.
- Engels, T., Kolomenskiy, D., Schneider, K., and Sesterhenn, J., “Numerical Simulation of Vortex-Induced Drag of Elastic Swimmer Models,” Theoretical and Applied Mechanics Letters, doi:10.1016/j.taml.2017.10.001.
- White, F., Fluid Mechanics Seventh Edition (McGraw Hill, 2011). ISBN:0073529346.
- ANSYS® Academic Research Mechanical, Release 18.1
- Huynh, C., Zheng, L., and Acharya, D., “Losses in High Speed Permanent Magnet Machines Used in Microturbine Applications,” Journal of Engineering for Gas Turbines and Power, doi:10.1115/1.2982151.
- Billingsley, J., Essentials of Dynamics and Vibrations (Switzerland : Springer International Publishing AG, 2017), ISBN: 978-3-319-56517-0, eBook.
- Anslyn, E. and Dougherty, D., Modern Physical Organic Chemistry, Illustrated Edition (University Science Books, 2006), ISBN: 1891389319.
- Ungar, E. and Kerwin, E., “Loss Factors of Viscoelastic Systems in Terms of Energy Concepts,” The Journal of the Acoustic Society of the America 34, 1962, doi:10.1121/1.1918227.
- Elliot, S., Tehrani, M., and Langley, R., “Nonlinear Damping and Quasi-Linear Modelling,” Mathematical Physical and Engineering Sciences, 2015, doi:10.1098/rsta.2014.0402.