Dry Sumps in F1

[gruntguru]

. . . As a side note, in turbomachinery where unbalance forces are significant (the main source of bearing loads) there tends to be a more pronounced friction increase with speed since unbalance forces increase with the square of angular velocity. This is definitely not the case with reciprocating engines where loads are dominating by firing, gears, springs etc. and inertial loads are relatively small.

Further to that, it is possible the turbomachinery runs slower as engine speed increases above 10,500 rpm (to maintain constant mass flow and therefore constant AFR). This will depend on which part of the compressor map is being used although the speed lines are usually near horizontal in the peak efficiency region.

The obvious consequence is a further reduction in the rate of increase of total frictional losses with increasing engine speed.

[saviour stivala]

The main function of the scavenge pump/s is the collection of oil, but blow-by gas also plays an important role in this. Just as a vacuum cleaner would not be able to suck-up dust in a vacuum, the scavenge pump/s would be unable to collect oil in the absence of blow-by gas. For this reason engine breathing supplies an optimum volume of blow-by gas from the upper section of the oil tank to the heads and the gear housings section where blow-by gas is not normally present. However, oil mixed with large quantities of blow-by gas can have a variety of negative effects on the feed pump. Including interfering with filling and producing bearing damage. For this reason after the oil is collected by the scavenge pump/s the oil and blow-by gas are separated in an oil-air separator that uses centrifugal separation, and are then sent to oil tank by means of separate channels. When a person drinks water through a straw, the water could not be drawn-up if the end of the straw was not completely immersed in the water. In the same way, the scavenge pump/s inlets must be completely immersed in oil in order for the pump/s to collect oil. Developments has shown that the initial design were oil struck by the rotating crankshaft and con-rod that was flowing into the scavenge pump/s under force of its own inertia was not optimal for stable collection of oil when cornering G-forces was produced in the opposite direction. Because the oil did not collect in the scavenge pump/s inlets. The use of an oil trap in the scavenge pump/s inlets increased the efficiency of oil collection. The scavenge pump/s used are of the internal compression type which also increase pump efficiency and oil collection.

[Tommy Cookers]

,,,, the scavenge pump/s would be unable to collect oil in the absence of blow-by gas. For this reason engine breathing supplies an optimum volume of blow-by gas from the upper section of the oil tank to the heads and the gear housings section where blow-by gas is not normally present.....

the mean pressure in the inlet and exhaust tracts is c. 4 bar
won't the interior of the heads tend to fill with this gas leaking through the valveguides ?
or is that interior at c. 4 bar ie not breathing to atmosphere ?

[saviour stivala]

,,,, the scavenge pump/s would be unable to collect oil in the absence of blow-by gas. For this reason engine breathing supplies an optimum volume of blow-by gas from the upper section of the oil tank to the heads and the gear housings section where blow-by gas is not normally present.....

the mean pressure in the inlet and exhaust tracts is c. 4 bar
won't the interior of the heads tend to fill with this gas leaking through the valveguides ?
or is that interior at c. 4 bar ie not breathing to atmosphere ?

“Gas leaking through the valve guides”. Please visit (F1 pneumatic valve spring, a closer look by Brian G 15 Sept 2016). The first pictures of a valve – valve guide – pneumatic cylinder assembly will tell you exactly were a gas leak through the valve guides will go.

[63l8qrrfy6]

,,,, the scavenge pump/s would be unable to collect oil in the absence of blow-by gas. For this reason engine breathing supplies an optimum volume of blow-by gas from the upper section of the oil tank to the heads and the gear housings section where blow-by gas is not normally present.....

the mean pressure in the inlet and exhaust tracts is c. 4 bar
won't the interior of the heads tend to fill with this gas leaking through the valveguides ?
or is that interior at c. 4 bar ie not breathing to atmosphere ?

Valve pneumatic pressure is higher than the exhaust pressure, if anything the air spring will leak into the exhaust.

[63l8qrrfy6]

Regarding pumping losses due to communication between bays. These losses will diminish as crankcase pressure is reduced - to zero in fact if a good vacuum could be achieved. Any ideas how low the crankcase pressure is in F1 engines? A google search indicates 20" Hg vacuum (0.3 Bar abs) is not uncommon in other race engines so I wouldn't be surprised if F1 run lower still.

I've got CA running 0.85 - 0.9 bar in its first iterations and later versions running 0.6 - 0.65 bar (RET 073).

[philippap32]

Wow!that is awesome!

Those numbers are mind blowing, a casual 11 scavenge pumps!

So in f1 and other racing series, they actually use an oil air separator rather than just baffles in a tank.

So in the real world we could lower to height requirements of a tank by having a centrifugal oil/air separator consultant SEO Paris... 75% engine speed! I love f1, even seemingly boring things are just fantastic!

You're absolutely right. I had the opportunity to attend the demo and it was really amazing.