F1technical.net

[quote=gruntguru post]
[quote="Tommy Cookers"]if drivers held a gear from eg 9500 to 11100 rpm they could reasonably use all the fuel rate allowed throughout that range but they don't seem to use that range
as I asked 4 years ago - using (as they do) the range 10500 - 12200 ..... what is the engine doing at 12200 with only the same fuel rate as it uses at 10500 ? ie for reasons I have put forward, it can't be brilliantly efficient at both these rpms
[/quote]
IMO at every engine speed, there will be a mapped operating point for WOT.
At some particular speed (about 11,000?) the efficiency will be optimal and maximum power will be produced.......[/quote]


so IYO maximum power and efficiency occur at some particular speed (notionally in the middle of the working range) and not at 10500 rpm

IMO an attempt to retain that efficiency down to 10500 would involve fuelling below 100 kg/hr at 10500 and would not be a very bad thing to do
efficiency depends on avoiding over and undercooling, and in use will fall short of testbed values as cooling rates cannot exactly follow the varying needs

Chicane wrote: ↑

11 Apr 2017, 18:06

Honda accelerates new engine for Bahrain test

"........ insisted the Honda chief, who is no longer worried about the vibrations of the propeller in Its assembly with the chassis.

Wow.....hopefully the translation is correct.

ENGINE TUNER wrote: ↑

11 Apr 2017, 16:38

JonoNic wrote: ↑

11 Apr 2017, 09:27

Hey guys. I remember reading here somewhere that generating heat is the main source of recovering electrical energy. If so, which would generate more heat? Based on the rev range will it be max torque or max power? Or are they not related?

Sent from my SM-A700F using Tapatalk

I don't know why anyone would say generating "heat" would be the main source of recovering electrical energy, if anyone could explain that it would be helpful.

Personally when I tune motors I have long since noticed that exhaust temp delta between turbo inlet and exit is minimal. Also when I test turbo's on a bench(for balance after a rebuild) we use compressed air(same source as for the pneumatic tools) and it actually spins the turbos up faster than the exhaust does, thus I have hypothesized that it is the air pressure that would be the main source for recovering energy with the TERS. The MHU"H" recovers energy from the spinning shaft that connects the turbine and the compressor, which is spun by air acting on the turbine. I could sit there and apply heat to the turbine all day and it isn't going to move 1 spin, it is the "momentum" of the air that the turbine derives its movement from. Also Why would you want your exhaust air temp to be high?

Well think of it this way, what does combustion do? It heats the air squished by the piston, that heat increases the volume of the air, that volume increase is what drives the piston, that same pulse of increased volume air drives the turbine. The volume increase and thus energy of the air would have never increased unless it had been heated, it's a similar principle to a steam turbine, the water turns to steam and it's volume increased, and that increased volume is responsible for the pressure increase that drives the turbine.

If heat didn't drive the turbine afterburners would be useless.

In other words, heat causes air to expand, the expansion provides kinetic energy, it truly is an inefficient process. The pressure post turbine is much lower than pre-turbine, that pressure differential guides the expanded air through the turbine blades(or wastegate when it's open).

That is why heat is energy, that is why nuclear reactors work, ya heat the fluid, the fluid expands and turbines are driven. This holds true from the sun down to the cells in your body.

I don't think the volume increases until it is allowed.
Here's the pressure, volume, and temperature relationship:
PV=nrT

dren wrote: ↑

11 Apr 2017, 20:53

I don't think the volume increases until it is allowed.
Here's the pressure, volume, and temperature relationship:
PV=nrT

It's always allowed, the gas almost always has an "out" also that's ideal gas law, it's not actual 18 billion species of gas molecules law.

It's a simple relationship for those that want to understand how pressure, volume, and temperature all relate.

Combustion chambers.

I came across this article about the new straight six Mercedes engine line. It peaked my interest because of the stepped bowl chamber they are using, which looks like another version, of what has been suggested for TJI chambers. Further on in this Patent looks to be a possible version that could be used. OK it's a diesel patent, but you could see the basic thinking. Replace the injector shown, with a concentric injector igniter. Bowl chamber much more open. Secondary injection event through that middle hole. Off the wall idea, maybe? I am sure you will let me know. The PDF has some ideas from his SAE paper.

ENGINE TUNER wrote: ↑

11 Apr 2017, 16:38

JonoNic wrote: ↑

11 Apr 2017, 09:27

Hey guys. I remember reading here somewhere that generating heat is the main source of recovering electrical energy. If so, which would generate more heat? Based on the rev range will it be max torque or max power? Or are they not related?

Sent from my SM-A700F using Tapatalk

I don't know why anyone would say generating "heat" would be the main source of recovering electrical energy, if anyone could explain that it would be helpful.

Personally when I tune motors I have long since noticed that exhaust temp delta between turbo inlet and exit is minimal. Also when I test turbo's on a bench(for balance after a rebuild) we use compressed air(same source as for the pneumatic tools) and it actually spins the turbos up faster than the exhaust does, thus I have hypothesized that it is the air pressure that would be the main source for recovering energy with the TERS. The MHU"H" recovers energy from the spinning shaft that connects the turbine and the compressor, which is spun by air acting on the turbine. I could sit there and apply heat to the turbine all day and it isn't going to move 1 spin, it is the "momentum" of the air that the turbine derives its movement from. Also Why would you want your exhaust air temp to be high?

You are doing something wrong if you can't detect a temperature delta, as that temperature delta is driving the turbine.

The power output of a turbine is as follows:

P = dH*m_dot

where

dH = Cp_in*T_in - Cp_out*T_out

Cp = specific heat capacity of working fluid, at inlet and outlet
T = temperature, at inlet and outlet
m_dot = massflow through the turbine

but also

dH = U_in*C_in - U_out*C_out

where

U = blade speed
C = gas velocity

In the case of a radial turbine this can be simplified to

dH = U_in*C_in

as C_out = 0

Tommy Cookers wrote: ↑

11 Apr 2017, 18:19

(and now wonder how the aviation ram air turbine works)

It's a windmill.

JonoNic wrote: ↑

11 Apr 2017, 09:27

Hey guys. I remember reading here somewhere that generating heat is the main source of recovering electrical energy. If so, which would generate more heat? Based on the rev range will it be max torque or max power? Or are they not related?

Maximum exhaust energy probably occurs near max power.

gruntguru wrote: ↑

12 Apr 2017, 00:47

JonoNic wrote: ↑

11 Apr 2017, 09:27

Hey guys. I remember reading here somewhere that generating heat is the main source of recovering electrical energy. If so, which would generate more heat? Based on the rev range will it be max torque or max power? Or are they not related?

Maximum exhaust energy probably occurs near max power.

I think you are right. However peak torque corresponds to peak cylinder pressure which gives the highest heat release rate. Or maybe the torque curve is flat between max torque to max power ?

ENGINE TUNER wrote: ↑

11 Apr 2017, 16:38

JonoNic wrote: ↑

11 Apr 2017, 09:27

Hey guys. I remember reading here somewhere that generating heat is the main source of recovering electrical energy. If so, which would generate more heat? Based on the rev range will it be max torque or max power? Or are they not related?

Sent from my SM-A700F using Tapatalk

I don't know why anyone would say generating "heat" would be the main source of recovering electrical energy, if anyone could explain that it would be helpful.

Personally when I tune motors I have long since noticed that exhaust temp delta between turbo inlet and exit is minimal. Also when I test turbo's on a bench(for balance after a rebuild) we use compressed air(same source as for the pneumatic tools) and it actually spins the turbos up faster than the exhaust does, thus I have hypothesized that it is the air pressure that would be the main source for recovering energy with the TERS. The MHU"H" recovers energy from the spinning shaft that connects the turbine and the compressor, which is spun by air acting on the turbine. I could sit there and apply heat to the turbine all day and it isn't going to move 1 spin, it is the "momentum" of the air that the turbine derives its movement from. Also Why would you want your exhaust air temp to be high?

The turbine does use heat it just because the blade design determines how much of the energy comes from impulse (motion of the gas) and how much comes from reaction (heat and expansion) of the gas.

Mudflap wrote: ↑

12 Apr 2017, 01:07

gruntguru wrote: ↑

12 Apr 2017, 00:47

JonoNic wrote: ↑

11 Apr 2017, 09:27

Hey guys. I remember reading here somewhere that generating heat is the main source of recovering electrical energy. If so, which would generate more heat? Based on the rev range will it be max torque or max power? Or are they not related?

Maximum exhaust energy probably occurs near max power.

I think you are right. However peak torque corresponds to peak cylinder pressure which gives the highest heat release rate. Or maybe the torque curve is flat between max torque to max power ?

The high heat release rate results in more efficient conversion of heat energy to piston work leaving a lower percentage of "waste heat energy" to the exhaust. Add to that the fact that peak torque (typically) occurs at much lower power and therefore much lower heat energy production. (wanted to say "heat release rate' but that has another meaning. )

At any rate the torque peak is somewhat irrelevant on these engines. The fuel rate limit is designed to permit near-flat torque below 10,500 rpm. (obviously the characteristics of the engine will result in deviation from that.)

[quote=PlatinumZealot]
The turbine does use heat it just because the blade design determines how much of the energy comes from impulse (motion of the gas) and how much comes from reaction (heat and expansion) of the gas.
[/quote]

to me this sounds like the most useful sentence written for a long time
(it has been seen before)

if it is correct ......
given that leaning increases the massflow of gas but lowers its temperature, does leaning give .......
(a) more exhaust heatflow
(b) less exhaust heatflow
(c) the same exhaust heatflow

and does this (leaning without loss of combustion efficiency) give .......
(a) increased MGU-H recovery ?
(b) decreased MGU-H recovery ?
(c) the same MGU-H recovery ?

Tommy Cookers wrote: ↑

12 Apr 2017, 09:40

The turbine does use heat it just because the blade design determines how much of the energy comes from impulse (motion of the gas) and how much comes from reaction (heat and expansion) of the gas.

to me this sounds like the most useful sentence written for a long time

if so ......
given that leaning increases the massflow of gas but lowers its temperature, is there .......
(a) more exhaust heatflow
(b) less exhaust heatflow
(c) the same exhaust heatflow

and does this .......
(a) increase the MGU-H recovery ?
(b) decrease the MGU-H recovery ?
(c) maintain the MGU-H recovery ?
[/quote]

More, less or the same compared to what?

EDIT: also: how is it that your quotes are always broken? It's like you break them on purpose