Speaker::Sean Ross
May 31st, 2018
ITherm 2018
100kW optical : get it to exit the aircraft in a particular way
Laser source - Controller - thermal management - power management
Main challenges:
Size/weight: laser system vs the thermal management system
Operating temp- Delta T requirements - T stability
Transient behavior-planned and unplanned transients
mechanical transients - on/off - get it to stop and start
insufficient heat sink: heat sink on the aircraft is the fuel
Requirements flow and generation- givers and takers - conversation
Main solutions:
increase operating temperature of laser diode
alter architecture for greater Delta
Fuel to photons:
1% system efficiency of system
Single phase
percent of size,weight,power in integration
engine at 250C - heat sink at 100
not enough convective cooling and/or air
Raising diode operating temperature
so that heat sink can be higher too which is convenient
Passive temperature stability
reduces control requirements
maintaining a certain ∆T
or cooling a certain existing ∆T
thermal architecture to have higher ∆T
Increase Delta T
mass flow rate - cooling rate
150kW <-> gallons per time to maintain
Solution:
Binning diodes
altering thermal architecture
thermally in series, same wavelength
temp to diode wavelength relation exists when manufactured
Latent heat involvement
boiling heat transfer
operating time scales of the two-phase solutions
transient types:
planned
time interval known and rates of ramps known
gentle ramps
unplanned
dynamic predictive avoidance
turn currents to diodes off to shunt the thermal transients
thermal transient:
affects bandwidth - temp excursion increases bandwidth- quality of beam
pump and valves can't match laser transients
transient mitigation:
System Engineering: upstream requirement management
Technology Readiness level:
is the tech mature enough for the overall system
Integration readiness level:
Causality analysis:
which sub-system enables what
what's the most causal
Manufacturing readiness level
Equally optimize all 3 readiness levels through iteration
be in pace for all the requirements
Evaporator: how close to the diode- transition from single to two-phase modes and the resulting system transients
Can one add heat somewhere to remove heat from somewhere else?
higher pressure and lower pressure stages in flow delivery - pressure recovery upon a certain process
Mixing valves
how to close loop in the thermal flow circuit
where to dump or does it require it
Duty cycles:
fuel-to-application,
application need and
equipment performance delivery level