F1technical.net

shady wrote:

denktank wrote:I mean this: https://grabcad.com/library/continuous- ... mpressor-1

The cutaway of the blade profile creates smaller compression chambers similar to a traditional multistage axial. One stage?

looks like compression is not only by compressor ''cone'' or core, but also in the space between blades, getting progressivily smaller toward combustion chamber. Don't know if this is the case by axial compressor, but probably is.

Axial and centrifugal compressors are "rotodynamic" machines. This means they work by accelerating the air to a high velocity (kinetic energy) then convert that KE to pressure by slowing it down again in a diffuser. In broad terms the PR of each stage is limited by the velocity ratio of the outlet to inlet of the rotating part (impeller).

It is obvious immediately that a centrifugal compressor impeller has a relatively slow inlet and much higher velocity outlet - being placed much further from the axis of rotation.

Axial compressors achieve a velocity difference through blade shape. At the intake side the blades are slicing through the air as it approaches roughly axially (small tangential velocity component). As the air passes along the blade, it is turned to rotate in the same direction as the rotating impeller so it now has a large tangential velocity component in addition to its axial (flow) component. It should be clear that the potential for achieving a large velocity ratio is much less for the axial compressor. If higher pressures are required, it is necessary to slow the air down in a diffuser (stationary vanes) and repeat the process in another stage.

PhillipM wrote:

wuzak wrote:Things like the double diffuser and the F-duct had loopholes in the wording.

I don't see that is the case here.

If the stages rotate at the same speed just with differing blade profiles and pitches, then maybe you could just join them with a rotating shroud and claim that it's still one stage as it's all one single rotating assembly? Depends more on how the regs define it rather than what it's actually doing in engineering terms...

Multiple stage axial compressors are often a single rotating assembly.

So no, that wouldn't fool anybody.

In any case, you would need a stator to get the best results.

gruntguru wrote:Axial and centrifugal compressors are "rotodynamic" machines. This means they work by accelerating the air to a high velocity (kinetic energy) then convert that KE to pressure by slowing it down again in a diffuser. In broad terms the PR of each stage is limited by the velocity ratio of the outlet to inlet of the rotating part (impeller).

It is obvious immediately that a centrifugal compressor impeller has a relatively slow inlet and much higher velocity outlet - being placed much further from the axis of rotation.

Axial compressors achieve a velocity difference through blade shape. At the intake side the blades are slicing through the air as it approaches roughly axially (small tangential velocity component). As the air passes along the blade, it is turned to rotate in the same direction as the rotating impeller so it now has a large tangential velocity component in addition to its axial (flow) component. It should be clear that the potential for achieving a large velocity ratio is much less for the axial compressor. If higher pressures are required, it is necessary to slow the air down in a diffuser (stationary vanes) and repeat the process in another stage.

Do you have an equation? Based on some of the schematics shared, that may not be the case if it is, a radial compressor still has waste gates, which is to say excess pressure.

wuzak wrote:
Multiple stage axial compressors are often a single rotating assembly.

So no, that wouldn't fool anybody.

In any case, you would need a stator to get the best results.

It's not a case of fooling anyone, it's a case of exactly how the regulations are worded, I will hold my hands up and say I haven't had a look at the specific wording yet though.

PhillipM wrote:

wuzak wrote:
Multiple stage axial compressors are often a single rotating assembly.

So no, that wouldn't fool anybody.

In any case, you would need a stator to get the best results.

It's not a case of fooling anyone, it's a case of exactly how the regulations are worded, I will hold my hands up and say I haven't had a look at the specific wording yet though.

Exactly, personally i think a good lawyer could argue that a single axial compression chamber with a single entry and a single exit is a still single stage compressor.

/devils advocate

djos wrote:
Exactly, personally i think a good lawyer could argue that a single axial compression chamber with a single entry and a single exit is a still single stage compressor.

/devils advocate

It may not be..

From what Ive read a single stage axial is a pair; rotor and 'nozzle'. Nozzle is misleading because it has the similar structure to the rotor, and is generally fixed. That still leaves a wide birth for execution.

shady wrote:

djos wrote:
Exactly, personally i think a good lawyer could argue that a single axial compression chamber with a single entry and a single exit is a still single stage compressor.

/devils advocate

It may not be..

From what Ive read a single stage axial is a pair; rotor and 'nozzle'. Nozzle is misleading because it has the similar structure to the rotor, and is generally fixed. That still leaves a wide birth for execution.

They are always fixed and are called stators. As was stated earlier the stator is what converts the velocity of the airflow into pressure by slowing it down.

djos wrote:

PhillipM wrote:

wuzak wrote:
Multiple stage axial compressors are often a single rotating assembly.

So no, that wouldn't fool anybody.

In any case, you would need a stator to get the best results.

It's not a case of fooling anyone, it's a case of exactly how the regulations are worded, I will hold my hands up and say I haven't had a look at the specific wording yet though.

Exactly, personally i think a good lawyer could argue that a single axial compression chamber with a single entry and a single exit is a still single stage compressor.

/devils advocate

Most axial compressors have a single entry and a single exit.

Not sure what you mean by "single chamber". The space between two stators?

shady wrote:

djos wrote:
Exactly, personally i think a good lawyer could argue that a single axial compression chamber with a single entry and a single exit is a still single stage compressor.

/devils advocate

It may not be..

From what Ive read a single stage axial is a pair; rotor and 'nozzle'. Nozzle is misleading because it has the similar structure to the rotor, and is generally fixed. That still leaves a wide birth for execution.

The stator ("nozzle") is not necessary if you build teh stages with counter rotation every second rotor.

Are there other Tech Regs besides these that would come into play?

5.1.6 Pressure charging may only be effected by the use of a sole single stage compressor linked to
a sole single stage exhaust turbine by a shaft assembly parallel to the engine crankshaft and within 25mm of the car centre line. The shaft must be designed so as to ensure that the shaft assembly, the compressor and the turbine always rotate about a common axis and at the same angular velocity, an electrical motor generator (MGU-H) may be directly coupled to it.
.
.
5.2.4 The MGU-H must be solely mechanically linked to the exhaust turbine of a pressure charging
system. This mechanical link must be of fixed speed ratio to the exhaust turbine and may be clutched.
The rotational speed of the MGU-H may not exceed 125,000rpm.
.
.
5.9.1 With the exception of devices needed for control of pressure charging systems, variable
geometry exhaust systems are not permitted. No form of variable geometry turbine (VGT) or variable nozzle turbine (VNT) or any device to adjust the gas throat section at the inlet to the turbine wheel is permitted.

wuzak wrote:
The stator ("nozzle") is not necessary if you build teh stages with counter rotation every second rotor.

Cant counter rotate, it contravenes the tech regs. (5.1.6)

With a CBC you can effectively unify the stator and rotor in what I would consider a single stage. The efficacy of that construction in an ICE is still a ways off..

I don't think the stages of an axial compressor are defined in the FIA regulations. While it is commonly stated as multi stage it is not the same as a centrifugal multi stage where the air moves from one housing to another. In a axial compressor it is just a series of rotating blades separated by guide vanes all within the same housing so the entire thing should be one stage unless FIA rule book says otherwise.

http://somersf1.blogspot.se/2015/04/mcl ... runit.html

Sommers on Honda PU!!!

Precisely my point, there isn't a single solitary word in the regulations that says "no compressor stators" It just specifies no variable geometry nozzles for the exhaust turbine. I don't see a regulations breach if your compressor is driven off the same shaft the MGU-H and exhaust turbine rotate on. It isn't specified what multiple stages means, the common definition of multiple stages is using separate cylinders to compress the air. If you use one compressor housing, it could be argued as being a single stage. Air is compressed in the single compressor housing where it passes through one intercooler and directly to the engine intake ports.