SV: "Leaf Blower" Forced induction idea

[Stewart Prince]

Espen
Here are the equations:
assuming upstream stagnation temp is 300 deg Kelvin, compressor efficiency is .7,
and specific heat ratio is 1.4,and the engine volumetric efficiency is .85
air density= 1.18 kg/m^3
cpair=1(kj/kg K)
Mdotair (kg/sec)=Eng_disp(cm^3) x vol_eff x density_ratio x air density(kg/m^3) x
RPM

---------------------------------------------------------------
                                                           2 x 60 x 100^3
power(kwatt)=

Mdotair(kg/sec) x cpair(kj/kg K) x Temp (K)/comp_eff x [press_ratio^.285 - 1]
try this with 2000 cc at 3000 rpm and you should get about
mdotair=.075 kg/sec
compressor power =3.5 kwatt
this might really work for your application.........


Greg Hermann wrote:

> At 1:30 AM 3/17/01, espen hilde wrote:
> >Hi!
> >Thanks for showing us in matematical terms !
> >Your calculation just showed me that its possible......
> >I am Norwegian I am used to think in 1.9l four banger  you are american,
> >350 is the natural thing....
> >350 is 5.735 litres thats 3 X 1.9l engines.
> >You clame that anything less than making the output times 2 of an engine is
> >not interesting?
> >The 1.9l needs 13.3HP to make 1 bar boost after your calculation...I would
> >be happy with 0.5bar thats 50% increase in power!!!  I would need half the
> >output , thats 6.65 hp ....2 Leafblowers 3.32 hp each ....Thats about what
> >a leafblower gives .....
> >and it could easily be tuned to give 5-6 hp each !
> >thanks
> >Espen
> >Dont be embarrased .....I use to have it on my head all the time...
>
> Espen-- the increase in compressor HP as boost increases is non-linear. IF
> it takes 14 HP to make 1 bar of boost , it will take less than 7 HP to make
> .5 bar of boost.
>
> Greg
> >
> >
> >
> >Stewart Prince [SMTP:sprince at csun.edu] skrev 16. mars 2001 23:12:
> >> Let' say you had a 350 ci engine, running at wot, 3000 rpm.  This is
> >about 1400 lbm/hr or air
> >> entering the engine.  If the boost density ratio was about 2, then we
> >have about 2800 lbm per hour
> >> of air entering the engine.  Assuming a specific heat of 1 kj/kg K and an
> >inlet temp of about 290
> >> K, with a compressor efficiency of about .7, this is about  30 kwatt, or
> >40 horsepower!  You need
> >> to get this power from somewhere,  and if it's an electric motor, a  40
> >horsepower electric motor
> >> is HUGE!!  What I'm trying to say is your leafblower might put out a
> >bunch of air flow, but not
> >> when the pressure is twice atmospheric.  If you used a mechanical device
> >such as a belt driven
> >> supercharger, you would get about 2800lbm/hr / .5 lbm/hp-hr/14 about 400
> >hp, but you would have to
> >> subtract off the 40 hp to run the s.c. so net is 360.
> >>
> >> espen hilde wrote:
> >>
> >> > Second tought.....use two and take them in series , one pushing the
> >other ,twice the pressure!
> >> > Espen.
> >> > How about a little factory making nos in the car?
> >> >
> >> >
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> >>
> >> --
> >> STEWART PRINCE
> >>
> >> PROFESSOR, MECHANICAL ENGINEERING
> >>
> >> CALIFORNIA STATE UNIVERSITY, NORTHRIDGE
> >>
> >>
> >>
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--
STEWART PRINCE

PROFESSOR, MECHANICAL ENGINEERING

CALIFORNIA STATE UNIVERSITY, NORTHRIDGE


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