Welcome
to MyElectricEngine.Com! I've created this page to present the work and
research I've done on electrical aerospace propulsion systems such as
magnetoplasmadynamic (MPD) and arcjet thrusters. This work is both my
hobby and the focus of my recently completed Masters
thesis
paper which I completed as a requirement of my Master's program. I
received my Bachelor's degree in Electrical Engineering with high
distinction from the Electrical
and Computer Engineering
Department at Worcester
Polytechnic Institute
in 2006, and followed that up with a Masters degree in Electrical and
Computer Engineering from Worcester Polytechnic Institute in 2007. If
you'd like to read the complete text of my Masters thesis, you can find
it here.
My original involvement in electrical propulsion began as a bit of a dining hall joke, and demonstrates the dangers of keeping too many engineers in one place. One of my mechanical engineering buddies remarked over a particularly uninspiring dinner that he had always wanted to see a magnetoplasmadynamic thruster fire and proceeded to explain how these devices work. The basic construction is simple enough, involving only a power supply, some capacitors, and a suitable spark gap. The first design was soundly within the category of "kludge", but adequately demonstrated this simple device which at the time amounted to a large spark machine. More advanced designs quickly appeared and were built, culminating in an independent study and finally a Masters thesis project. I'm currently employed in research and development at Boeing Research and Technology, which is pretty excellent, so I'm not looking for a job, but you can still feel free to e-mail me at MyElectricEngine@gmail.com and take a look at my resume here or view it as a word document here. Anyway, on to the good stuff.
Here is a list of all of the projects that I've documented. Watch for updates and improved designs.
I spend a lot of time researching and collecting information on a wide range of subjects, much of which is dispersed widely and often of an obscure nature. I've collected those bits of information that I find useful here, in hopes that other people may find it useful as well.
For the time being, everything that doesn't neatly fit into the other categories will go here. That'll consist of smaller projects, circuit examples, and other bits of information.
visitors since September 2007 Questions? Comments? Suggestions? E-Mail me at MyElectricEngine@gmail.com Copyright 2007-2010 by Matthew Krolak - All Rights Reserved. Don't copy my stuff without asking first. |
This
is the
project that started it all, and attempts to find a reasonable thruster
package that can provide high levels of thrust at high specific impulse
levels on a budget. It uses electromagnetic forces to accelerate an
electrically conductive, or ionized, propellant gas out of a
nozzle, and attempts to sidestep the limitations of chemical rockets by
eliminating the dependency on thermal expansion of the propellant..
This description also includes brief introductions to the various
subsystems that were built to support this design. The other components
used in this project
are more thoroughly described in the sections below
If
high energy
experiments are to be performed on a reasonable budget then chances are
you're going to need to operate your device in a pulsed mode - i.e. at
very high power levels for very short periods of time. This approach
strongly suggests using a carefully designed capacitor
bank. Both the electrical and mechanical design issues are
explored, including the reduction of parasitic inductances and the
mechanical requirements of high current conductors. Here's my design
for a 28kJ electrolytic
capacitor bank capable of delivering 200 Megawatts or more.
How do you
accurately and reliably trigger a high current discharge across a spark
gap, such as the nozzle of a MPD or arcjet thruster? This
problem is
deceptively difficult, especially on a student's budget. We can take
some advice from the design of Tesla Coils and arc welding equipment
and develop a relatively robust solution using common components to
create a high voltage, high frequency ignition circuit.
The
previously described
ignition circuit works very nicely, but is very heavy and
generates
a huge amount of EMI that persistently fouled up sensors, interfered
with data collection, and even crashed computers within several tens of
feet. This design uses the same concepts but replaces the bulky and
heavy line frequency neon transformer with a more compact high high
frequency transformer. Similarly, the spark gap is replaced with solid
state switches that can operate at high frequency without the EMI
associated with a spark gap.
Higher
operating pressures required the design and manufacture of several
custom components, particularly the high pressure valve based on a
simple ball valve and an electric motor. 
Gasses
under high pressure or at high velocities behave in ways that seem
counter-intuitive to our everyday experience, but can greatly influence
how certain flows behave. This page explains some of the basic
differences between incompressible flows and compressible flows, and
how they differ from how we might otherwise expect them to behave.
If you're ever looking to purchase a valve or gas
solenoid, you're probably going to come across this funny parameter
called cv.
As an electrical engineer, no one every explained this to me, so I had
to figure it out myself. Here's the important stuff you need to work
with this parameter laid out for you so you can find the flow of a
fluid through a valve.
Since
most of the projects and information on this site pertain to making big
sparks, ignition coils are a good topic to cover. Ignition coils are
magnetic devices found in older automobiles and are used to generate
high voltages. Topics such as operating principles, measuring
characteristics, electrical modeling, and driver circuits are covered.