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18.05.2011 1
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
Energy generation by rampressure in mortar and artillery
fuzesNDIA E2S2 symposium & exhibition – may 12th 2011
18.05.2011 2
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
Outline• Introduction
• Functional principle of the generator
• Simulation with OpenModelica
• Results of the simulation
• Parameter studies
• Comparison between simulation and experimental results
18.05.2011 3
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
Introduction/ motivation• Electronic systems in fuzes need electrical power• Environment contains a lot of energy, which can be
converted into electric energy• Storage of batteries is a problem
– Loss of charge during storage
18.05.2011 4
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
Functional principle of the generator• Linear spring mass system• Induction of voltage in a coil due to magnet movement• External force due to ram pressure
– Magnet works like a valve: it opens and closes an outlet periodically
Magnet CoilSpring
xkV e ⋅=Basic equation:
18.05.2011 5
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
Generator model
Magnet (NdFeB)
CoilAir outletAir inletSpring
18.05.2011 6
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
Experimental fuze setup
Fuze casing (left) with energyharvesting generator
Fuze combined with energyharvesting generator
18.05.2011 7
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
Simulation with OpenModelica• Using the open source software ‘OpenModelica’• Object-oriented programming• Using differential equations for describing the single parts
of the model– Using coupling constant for electric coupling– Using compressible ideal gas model
• Numerical solving of a system of differential equations• About 50 parameters and over 120 variables
18.05.2011 8
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
Why OpenModelica?• Spring-mass model does not have a ram-pressure
dependency• Simulation of periodical opening of the outlet• Using compressible gas• Object oriented programming• Connects multiphysic equations
– electrical– mechanical– aerodynamic
18.05.2011 9
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
pressuresource
Inletvalve volume
magnet damperspring
internalresistanceinductivity
electromagneticcoupling
loadresistance
pressuresink
outlet valve
leakage
18.05.2011 10
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
Occurring ram pressure
Dependence of ram pressure on velocity and flight time
18.05.2011 11
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
Results of simulation
Pressure over time pressure over volume
18.05.2011 12
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
Pressure and voltage
voltage over timePosition of magnet over time
18.05.2011 13
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
Variation of ram pressure
pressure over volume voltage over time
18.05.2011 14
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
Variation of inlet and outlet
voltage over diameter ratio
• for high ratios voltage saturationoccur
18.05.2011 15
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
Power efficency
power over pressure pressure-volume-circle for different rampressure
18.05.2011 16
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
Comparison between simulation andexperimental results
• curve form is similar• frequency of the simulated curve is slightly to high
18.05.2011 17
Institute for automation engineeringMeasurement and information technologyKossebau/ Prof. Rothe
Conclusions• Power can be increased by variation of system parameters• Power decreases with decreasing ram pressure• Available mechanical and electrical power decreases with
volume• Electrical power efficiency is about 0.1-2 % of the mechanical
power