OMG.......why has no-one made an adaptor plate for the t/b ?
Okay, I've kept my mouth shut for long enough......
You lose pressure, not air-flow from 90 degree bends so you make the compressor wheel possibly run outside a certain efficiency range and therefore lose power.
You lose pressure, not air-flow from 90 degree bends so you make the compressor wheel possibly run outside a certain efficiency range and therefore lose power.
Computer games don't affect kids I mean if PacMan affected us as kids, we'd all be running around in darkened rooms, munching magic pills and listening to repetitive electronic music :D
-
igottasicjb
- I like starions more
- Posts: 161
- Joined: Sat Mar 27, 2004 3:41 pm
- Location: brisbane
bends don't drop pressure temp does i'm not a big fan of arguing on the net there's no point however i've just spent the last 7 weeks learning aeronautical physics at college and to my shock i actually passed :o For the past 5 days we have been working on an air conditioning system off a boeing 737 at college. these systems use bleed air from both jet engines to power a smaller air conditioning turbine. now your prob wondering whats this got to do with intercooler pipes and pressure losses ect, well the bleed air is taken from 8th and 15th compressor stage from each jet engine, 8th stage hovers around 45psi and 15th stage is used at low engine speed so also around 45psi. Ok now the air conditioning turbines sit about 6 metres infront of the tail, therefore there is about 27 metres of 1.5 inch alloy/stainless pipe and a countless no. of bends. even over this distance there no pressure drop. the only thing that will change the pressure of a gas in a fixed container is change the size of its container, or change the temp of the gas nothing else.
boost = the replacement for displacement
<<<PIGS can fly
<<<PIGS can fly
The thing is that air in an engine inlet is not in a fixed container. It is flowing. Flow is caused by a pressure difference. No presure drop no flow. Of course bends cause a presure drop in a flowing air stream. The only question is whether it is a significant drop. That depends on the flow velocity and is calculable. Me thinks you need a fluid mechanics text.igottasicjb wrote:bends don't drop pressure temp does ..........the only thing that will change the pressure of a gas in a fixed container is change the size of its container, or change the temp of the gas nothing else.
Have fun with the numbers.
Cheers
Boris
:DJPC wrote:So you remembered your Boyle, Charles and Avagadro Gas Laws, huh?toysrus wrote:Temperature and Pressure are directly related...........
Computer games don't affect kids I mean if PacMan affected us as kids, we'd all be running around in darkened rooms, munching magic pills and listening to repetitive electronic music :D
-
jakobsladderz
- Mine is bigger than yours
- Posts: 286
- Joined: Wed Feb 11, 2004 10:32 pm
- Location: Ballarat
The pv=nrt rule, relating pressure, temp and volume, applies to both flowing and static fluids but has little to do with the losses in a bend or any pipe for that matter.
The losses through a bend will indeed show up as a pressure difference between the inlet and outlet. The problem is related to both the inertia of the air (doesn't want to change direction easily, like any other object with mass) and the viscosity (how well it sticks to itself and other surfaces). If you have a really big pipe with very low speed or low density fluid flow, you would loose almost nothing from a bend. If you had a very dense fluid or high speed flow, you would lose more.
Some losses are caused by turbulence, where the air gets thrown around in every direction, eventually the motion turns to heat.
The easiest way to really learn what's going on is to put pressure gauges in the various sections of the system and measure the difference.. I am going to do this soon on my car and I'll post up the results.
The losses through a bend will indeed show up as a pressure difference between the inlet and outlet. The problem is related to both the inertia of the air (doesn't want to change direction easily, like any other object with mass) and the viscosity (how well it sticks to itself and other surfaces). If you have a really big pipe with very low speed or low density fluid flow, you would loose almost nothing from a bend. If you had a very dense fluid or high speed flow, you would lose more.
Some losses are caused by turbulence, where the air gets thrown around in every direction, eventually the motion turns to heat.
The easiest way to really learn what's going on is to put pressure gauges in the various sections of the system and measure the difference.. I am going to do this soon on my car and I'll post up the results.
Trispen - A form of intelligent grass. It grows a single, tough stalk and makes its home on lawns. When it sees the lawnmower coming it lies down and pops up again after it has gone by. (Douglas Adams, The Meaning of Liff)
JA Starion - Mechanic's Training and on-road EFI testing laboratory.
JA Starion - Mechanic's Training and on-road EFI testing laboratory.
-
jakobsladderz
- Mine is bigger than yours
- Posts: 286
- Joined: Wed Feb 11, 2004 10:32 pm
- Location: Ballarat
The article mentions the relationship b/w the length of straight that would be equivalent to a corner, which is fine. What it doesn't mention is the pressure drop caused by either. Sure a 3" tight bend may be the equivalent of 3 metres of straight but both may cause a pressure drop of 0.1 psi I.E, 3/5 of FA.
The problem with pressure drops in the system is that the turbo has to work harder to make the same manifold pressure, increasing exhaust back pressure. Increased backpressure means less pumping efficiency/volumetric efficiency and lost power. So any improvements in intake flow means either more boost at the engine for the same backpressure, or less backpressure for the same boost. either way you win.
The problem is in locating what in the entire system is causing the biggest restrictions, then sorting them out. It's kind of like the weakest link in the chain scenario. if you have a big restriction in one part, you could expand every other part and see no improvement, but if you fix the restriction itself, instant gratification.
It's not rocket science, just some logic and having the equipment, patience and means to work it all out, or the experience to know where the problems are likely to be. I don't have so much experience, so I'll try the measuring methinks.
The problem with pressure drops in the system is that the turbo has to work harder to make the same manifold pressure, increasing exhaust back pressure. Increased backpressure means less pumping efficiency/volumetric efficiency and lost power. So any improvements in intake flow means either more boost at the engine for the same backpressure, or less backpressure for the same boost. either way you win.
The problem is in locating what in the entire system is causing the biggest restrictions, then sorting them out. It's kind of like the weakest link in the chain scenario. if you have a big restriction in one part, you could expand every other part and see no improvement, but if you fix the restriction itself, instant gratification.
It's not rocket science, just some logic and having the equipment, patience and means to work it all out, or the experience to know where the problems are likely to be. I don't have so much experience, so I'll try the measuring methinks.
Trispen - A form of intelligent grass. It grows a single, tough stalk and makes its home on lawns. When it sees the lawnmower coming it lies down and pops up again after it has gone by. (Douglas Adams, The Meaning of Liff)
JA Starion - Mechanic's Training and on-road EFI testing laboratory.
JA Starion - Mechanic's Training and on-road EFI testing laboratory.
Bends bend my mind!
So look at what lag may be introduced. We are basically comparing these two options.
Let's do some rough numbers. The additional distance with the additional bends is about 750mm. To keep the numbers nice and round, a 2L four stroke engine at 3000rpm pumps a nominal 1L per rev =3000L/min/60sec/min= 50L/sec. Nominal velocity in a 52mm id tube would then be
V=Q/A =0.05m^3/sec/(pi*0.052^2/4)=25m/sec
Time = L/V= 0.75m/25m/sec= 0.03seconds. Probably not significant.
-----------
Next lets look at the above assumption that flow is laminar. Intuitively, coming of a turbine compressor wheel spinning at a gazillion revs and settling down to travelling at 25m/sec through a 52mm tube does not sound like laminar flow, however lets check the gut feel. If it is laminar flow then the Reynolds number will be below 2000.
Re=Vd/v =25m/secx0.052m/1.8x10e-5msq/sec for air at 50degrees c
ie Re=72000.
Guess that is a bit bigger than 2000. Ding!
-----------
Who's going to calc the head loss?
Boris
Let's do some rough numbers. The additional distance with the additional bends is about 750mm. To keep the numbers nice and round, a 2L four stroke engine at 3000rpm pumps a nominal 1L per rev =3000L/min/60sec/min= 50L/sec. Nominal velocity in a 52mm id tube would then be
V=Q/A =0.05m^3/sec/(pi*0.052^2/4)=25m/sec
Time = L/V= 0.75m/25m/sec= 0.03seconds. Probably not significant.
-----------
Next lets look at the above assumption that flow is laminar. Intuitively, coming of a turbine compressor wheel spinning at a gazillion revs and settling down to travelling at 25m/sec through a 52mm tube does not sound like laminar flow, however lets check the gut feel. If it is laminar flow then the Reynolds number will be below 2000.
Re=Vd/v =25m/secx0.052m/1.8x10e-5msq/sec for air at 50degrees c
ie Re=72000.
Guess that is a bit bigger than 2000. Ding!
-----------
Who's going to calc the head loss?
Boris
Who is online
Users browsing this forum: No registered users and 25 guests