Departmental Brochure (PDF) - Mechanical Engineering - Johns ...

The ChairMAN
WILL KIRK/ HOMEWOODPHOTO.JHU.EDU
Message from the Chair
Professor and Chair, Kevin Hemker
As I walked into Latrobe this morning I
could not help but see a very muddy Baja
car parked in the first floor hallway. The car
and students who designed, built and raced it
competed in a national SAE event this past
weekend. Out of over 100 teams our Hopkins
team finished 3rd in the Design Report, 3rd in
Maneuverability Events, and 9th overall, by far
the team’s best finish and first ever top 10.
Design-build-fly, another club team that is led
by mechanical engineering undergraduates,
recently flew their custom built airplane in
Tempe Arizona and finished 21st out of over
60 teams. Combined with our newly designed
freshman experience and our capstone Senior
Design projects, these activities represent a
significant advancement in the level of design
and innovation that is occurring on the
Homewood campus.
Rest assured that the undergraduates are
not the only ones having fun in the lab these
days. Based on data that I collected during
recent faculty reviews, I was able to determine
that, on average, each day of the year a JHU
Mechanical Engineering faculty member is giving
an invited talk, somewhere in the world.
This newsletter contains numerous vignettes of
the myriad of research activities that our undergraduate
research assistants, graduate students,
postdocs, and faculty are engaged in. I invite
you to go to http://www.me.jhu.edu/ to read
more about the fantastic discoveries and
advances that are being made by Hopkins
mechanical engineers.
In this past year our Department has
welcomed our first teaching-track faculty
members, Dr. Nathan Scott and Dr. Stephen
Marra, and a new assistant professor, Dr.
Dennice Gayme, with expertise in fluids, control
theory and energy. They are infusing our
undergraduate curriculum with hands on experiences,
opportunities for innovative design,
and introduction to grid integration of renewable
energy systems. Overall, our faculty have
received numerous accolades over the past year,
highlighted by the election of Andrea
Prosperetti to the National Academy of
Engineering and receipt of a Presidential Early
Career Award in Science and Engineering by
Noah Cowan. This edition of ME Force has
been written to provide you with an idea of the
many exciting developments and activities that
are occurring in our department.
I hope you will enjoy reading this installment
of our Newsletter, and I look forward to
receiving your comments and feedback. Please
do stay in touch.
Kevin Hemker
Alonzo G. Decker Chair of Mechanical
Engineering
Professor and Chair, Department of Mechanical
Engineering
MECH E FORCE Editorial Team Members:
Charles Meneveau (Senior Editor), Gregory Chirikjian, Rajat
Mittal, Thao “Vicky” Nguyen, Deana Santoni, Sean Sun
Published by the Department of Mechanical Engineering,
Johns Hopkins University.
Design: Johns Hopkins University Marketing and
Creative Services
Contact us: Please send us any alumni news and thoughts
on what you’d like to see in Mech E Force to:
Department of Mechanical Engineering,
223 Latrobe Hall, Johns Hopkins University,
3400 N. Charles Street, Baltimore MD 21218
Phone: 410-516-6782
Fax: 410-516-7254
Email: mech_eng@jhu.edu
URL: http://www.me.jhu.edu
Research Highlights, from page 1
generated microjets in air. In the latest experiments,
the velocity of water microjets with a
diameter of about 1/10th of a human hair, has
been measured to exceed 850 m/s (just short
of 2,000 mph), nearly Mach 3. A possible
application would be to needleless injections.
Most vaccines and protein therapeutics are
currently delivered using needles and syringes,
a method not without problems: from the
transmission of HIV and hepatitis B due to
needle re-use (in particular in developing
countries), to accidental needle injuries and
even needle-phobia.
This remarkable phenomenon results from
the combination of new micro-fluidic knowledge
with the principle underlying an old and
well-known device, the so-called “shaped
charge.” This is an explosive ordnance based
on the so-called Munroe effect, accidentally
discovered in 1888 by Charles Munroe while
working for the U.S. Navy.
The effect can be explained with reference
to figure 1. When the explosive is ignited on
the right of the figure, a strong shock wave
propagates toward the left. The hollowed part
of the explosive is lined with a metal layer
which, under the action of the shock wave, is
strongly accelerated inward as indicated by the
arrows. The focusing effect caused by the
geometry is so strong that the metal essentially
liquefies as it accumulates on the axis of symmetry
of the device and is accelerated to
velocities of several kilometers per second sufficient
to penetrate tank armors.
In the supersonic microjet the same focusing
idea is exploited by arranging for a curved
liquid meniscus, but in this case the shock
wave is caused by the rapid vaporization of
the liquid under the action of a low-energy
laser pulse lasting a few billionths of a second
Fig. 1: Principle of a shaped charge. The shock wave
caused by the ignition of the explosive hits the metal
lining the hollowed surface of the charge and accelerates
it toward the axis. The resulting focusing is so
strong that the metal liquefies and is ejected at
velocities of several kilometers per second.
2 www.me.jhu.edu
mech_eng@jhu.edu