Dr. James C. Huan
OptiMax Dynamic, LLC
August , 2014
OptiMax Dynamic, LLC

Why Impulsive or Unsteady Propulsion?
 Marine animals chose it over millions of years of natural
selection;
 Theory and laboratory tests proved its superiorities;
 Athletes manually use it in boat racing.

Why Not Impulsive Propulsion for All Marine Vehicles?
 Man-made device to achieve a simple and efficient cycle for
Impulsive Propulsion for marine vehicles is the challenge!

Patented Side-Intake Concept for MIT Overcame the Challenge!
 Working principle of the Side-Intake MIT;
MIT examined from Efficiency, Linearity and Effectiveness perspectives;
 Development plan for MIT.


A View for the Future
OptiMax Dynamic, LLC

Marine animals Chose it Over Millions of Years of Natural Selection
A fundamental feature of Impulsive Propulsion is the impulsive jet flow
characterized by well-structured large thrust vortices such as vortex rings.
 Fish impulsively sweep its caudal fin to
generate a wavy impulsive jet (see Fig.-1);
 DPIV revealed chain-connected inclined
vortex rings in the jet flow from fish.
reverse Karman vortex street
Caudal Fin
chain-connected inclined vortex rings
Fig.-1
 Squid contracts body muscle to generate
impulsive jet through its siphon;
 Squid is able to generate perfect vortex rings. reverse Karman street
For the size of a giant
squid and how quick it acts for
its prey, watch TV news clip at:
a perfect vortex ring
https://www.youtube.com/watch?v=bK5IdL23
AMs
OptiMax Dynamic, LLC
First-order Theoretical Analysis

Vinf
Vjet
steady propulsion jet flow
(unstable vortices turn into turbulence)
T
T  Q  (V jet, x  V inf )
 
W useful
W in

V inf  T
1 / 2 Q  (V jet  V inf )
2
2

1 2
1 2
W in  Q  ( V jet  V inf )
2
2
2  V inf
V inf  V jet, x
from Jojn Dabiri, CalTech
Jet or Ideal Efficiency!
 Energy losses in steady propulsion devices
(propellers or impeller-driven pump jets):
impulsive propulsion jet flow
• viscous shear loss (vorticity instability and turbulence)
• cavitation loss
• slip losses including axial and tangential
 Impulsive Jet from piston-cylinder setup:
• minimum loss from vorticity instability and turbulence;
a perfect jet model
• axial slip loss only, meaning achieving ideal efficiency. (only
axial flow velocity !)
OptiMax Dynamic, LLC

Findings from Experimental Studies on Impulsive Jet Flow
 Piston-cylinder setup is ideal for optimum Vortex Ring generation
resulting in a momentum augmentation in jet flow through:
• ambient mass entrenchment into the Vortex Ring;
• over-pressure at jet exit to accelerate the Vortex Ring (Gharib, JFM, 1998).
 Impulsive Jet could increase propulsive efficiency up to
50% over the steady jet (Ruiz, Whittlesey & Dabiri, JFM,
2011).
“A Universal Time Scale for Vortex Ring Formation”
by Gharib, M.,et al., JFM, (1998).
a VRT model
from Jojn Dabiri, CalTech
VRT
Krieg & Mohseni,
(J of Oceanic Eng.,2008)
vortex ring from
piston-cylinder setup
OptiMax Dynamic, LLC

Athletes Manually Use Impulsive Propulsion in Boat Racing
 Oar cycle achieves efficient impulsive
moving direction
propulsion, but manually:
• impulsively expel water to maximize
the reverse Karman vortex for thrust;
• recover oar through air for minimum
energy waste;
 Analysis shows using piston-cylinder
setup to expel water will be more
efficient than oars (see analysis):
Assume: (1) force, ‘N’, in blade normal dir.;
(2) no friction.
a practical example of reverse Karman street !
u s  u n   R  V sin 
Slip velocity:
Power loss on blade: E blade  N ( R  V sin  )
ωR
Power Input: E input  N  R
Propulsive efficiency: 
ideal efficiency only

V sin γ
E input  E blade V sin 

E input
R
at    / 2
ωR  V sin γ
!
I 
V
R

1
1 a
ω
an oar analysis model
OptiMax Dynamic, LLC

Give a Summary:
 Impulsive Propulsion is proved to be superior over Steady Propulsion.
 Piston-cylinder setup is ideal for Impulsive Propulsion.
 Then, why not Impulsive Propulsion?
Man-made device to achieve a simple and efficient cycle for
Impulsive Propulsion for all marine vehicles is the challenge !
 Patented Side-Intake concept for MIT for the first time overcame the
challenge !
Take a break here if you want !
OptiMax Dynamic, LLC

Working Principle of the Side-Intake MIT System





open intake holes near discharging end.
require a valve to open and close
intake holes.
separate cylinder with a dry and a wet
compartment during piston motion.
achieve oar-like cycle, but under water.
need two cylinders for continuing water
flow from inlet to jet exit.
Q    A p  V p    Ao  V o    A j  V j
T  Q  (V j  V i )
1
1
Wp  Q ( Vj  Ua )
2
2
2
2
valve opened
Intake process
 propulsor 
W useful
Wp

2 U a
V j  Vi
2
2
 2
2
V j  Vi V j  U a
valve closed
Continuous flow during a cycle
Discharge process
OptiMax Dynamic, LLC

Side-Intake MIT Actual Configuration
(1) jet nozzle;
(2) 4 cylinders;
(3) 4 inner ring rotational valves;
(4) ball bearings;
(5) permanent magnets;
(6) 4 electrical coil winding pats;
(7) 4 pistons;
(8) 4 absorbing springs, one for each piston;
(9) baffle cap.
MIT is similar to Axial Piston Pump,
but for flow rate and momentum
producing.
OptiMax Dynamic, LLC
MIT examined from Efficiency, Linearity and Effectiveness
perspectives

 MIT can have a more than 30% efficiency increase over the best marine
propulsor in use today
 overall 
Thrust Power
Input Power to Propulsor

V ship  Thrust
Input Power to Propulsor
 overall   jet   flow   pump   m
V ship  Thrust
 jet 
flow kinetic energy required

flow kinetic energy required
 flow 
total kinetic energy added to fluid
 pump 
total kinetic energy addd to fluid
mechanical
For MIT:
work done on fluid
2  Vi
V j  Vi

2
1  Ai / A j
(e.g. swirl loss)
 m : mechanical
electrical
  ideal
• PD efficiency is nearly a constant;
• PD efficiency is much higher than ND;
and • ND efficiency is a nonlinear ‘‘bell curve’’.
efficiency
 flow  1  m  1
ω
 pump  90 % and a const
 MIT
overall
  jet   ideal
flow all in axial direction !
control volume for MIT
(even without considering
momentum augmentation from Vortex Ring)
having swirl loss !
control volume for propeller
OptiMax Dynamic, LLC

MIT examined from Efficiency, Linearity and Effectiveness
perspectives (cont’d)
 MIT is a linear performer, which is extremely important for vehicle’s
acceleration and maneuverability !
• because MIT is a PD pump and its  pump is nearly a constant
regardless of changes to a vehicle’s load condition (e.g. during
acceleration or maneuvering).
 MIT is more effective than the most effective pump jet ever designed
• Effectiveness of a power machine is a power density question.
• For a propulsor, ideally to have the most compact system to generate
a given thrust power without sacrificing its efficiency.
Let’s look at the thrust equation: T  Q  (V jet, x  V inf )
• To Increase (V jet, x  V inf ) for larger T leads to larger slip loss and so
sacrifices efficiency, not good !
• Ideally, it is to increase flow rate, Q , for larger T.
• However, Q is proportional to a propulsor’s size.
• The effectiveness question is to answer: among the same size of
propulsors, which propulsor can produce the most flow rate, Q ?
Let’s do an analysis!
OptiMax Dynamic, LLC
 MIT is more effective than the most effective pump jet ever designed (cont’d)
• The capacity coefficient,
C Q  Q / nD
•
•
•
•
3
where: n is RPM, D is the diameter of the propulsor
determines the effectiveness or compactness of a propulsor !
For the same diameter and RPM, the larger, CQ , the more effective or compact.
Axial-flow pump jet is the most
compact propulsor in use !
For Axial-flow pump, CQ is not a const.
because Q and n is in a very nonlinear
relation.
The highest CQ ever found is in
ONR AxWJ-2 Pump Jet, CQ, ONR =0.85 !
• For MIT, CQ is a constant and equals to
C Q, MIT  Q / nd    
3
MIT cylinder d and system D
where   L / d (stroke to diameter ratio)
Pump Jet D and MIT d relation: d  D /(1 
2)
Using D instead of d: C Q, MIT  Q / nD 3  0 . 071    
For
C Q, MIT
C Q, ONR
 0 . 26    1
i.e. just make
  3 .8
A typical axial-flow pump
curve. The best efficiency
CQ is around 0.55
MIT can be more effective !
Besides, because CQ, MIT is const., we can always increase n for large Q !
OptiMax Dynamic, LLC

Development plan for MIT
(This slide is purposely blanked !
Interested readers can obtain the information through
direct contacting us.)
OptiMax Dynamic, LLC
 MIT is a disruptive technology in maritime industry.
 As a jet engine is the heart for an airplane, MIT is the heart for a
marine vehicle.
 MIT powered by advanced electric drive will bring about a new
revolution in the industries of shipbuilding and maritime
transportation.
Q&A
OptiMax Dynamic, LLC