[KVRC] Khamsin Virtual Racecar Challenge 2016

[CAEdevice]

The drag and downforce performance predicted by the simulation are:
Total drag: 1761.38 N
Front wing(s) drag: 287.19 N
Rear wing(s) drag: 287.16 N
Drag coefficient - Cd: 0.84
Drag area - Cd.A: 1.47 m2
Total Downforce: -3999.75 N
Front wing(s) downforce: -1884.53 N
Rear wing(s) downforce: -1846.47 N
Downforce coefficient - Cl: -1.91
Downforce area - Cl.A: -3.34 m2

CoP of downforce: 1.532 m along streamwise (Y) direction from Y = 0.00 m.
KVRC Only: Corrected CoP of downforce: 1.591 m along streamwise (Y) direction from Y = 0.00 m.

The pressure at intake and exhaust are:
Engine intake, Area: 0.018m2 - Compliant
Surface integral of pressure: 4.35 Pa.m2
Engine exhaust, Area: 0.011m2 - Compliant
Surface integral of pressure: -4.59 Pa.m2
Cooling intake, Area: 0.401m2 - Compliant
Cooling exhaust, Area: 0.402m2 - Compliant
Differential of surface integral of pressure: -269.23 Pa.m2


A good start to the year now to get some more downforce.

Very good df/dr ratio!

... but the cooling pressure differential should not be positive? Or I am interpreting it in the wrong way?

[etsmc]

is the differential not this one??
Differential of surface integral of pressure: -269.23 Pa.m2

[TalnoRacing]

Overall I am very pleased with my official results. After running the "light" simulation only, the official results show an increase in downforce of ±1,400N and increase in drag of ±100N compared to the best I achieved in "light" mode. COP is in the exact same spot, which is a little too much to the rear, but this can be easily fixed.

Can someone please help to clarify my cooling-intake results? My cooling-intake area was 0.102m2 as per the official results, but the results show it as "not compliant". The rules require a cooling-intake area of 50,000mm2 and I have an actual area of 51,000mm2. Am I missing something or not understanding the results? The pressure differential is 14.98Pa.m2.

[CAEdevice]

Overall I am very pleased with my official results. After running the "light" simulation only, the official results show an increase in downforce of ±1,400N and increase in drag of ±100N compared to the best I achieved in "light" mode. COP is in the exact same spot, which is a little too much to the rear, but this can be easily fixed.

Can someone please help to clarify my cooling-intake results? My cooling-intake area was 0.102m2 as per the official results, but the results show it as "not compliant". The rules require a cooling-intake area of 50,000mm2 and I have an actual area of 51,000mm2. Am I missing something or not understanding the results? The pressure differential is 14.98Pa.m2.

Don't worry, 50000mm2 is ok, the "not compliant" message is referred to the old rules.

[TalnoRacing]

Don't worry, 50000mm2 is ok, the "not compliant" message is referred to the old rules.

OK, thank you.

[variante]

Quite happy with my results: they are in line with my 10000N target (actually, i'm 45N short). I wonder how many cars will be in that downforce range and, consequentially, how much downforce I can sacrifice to give more airflow to the cooling duct...
In fact, I now have to deal with cooling problems: pressure differential is just 1/3 of the necessary one, thus the engine will run with just 12% of the power!! Expect my car to be very slow...
Still, I don't think that's going to be a problem for me, as I've designed the cooling system to be modular and flexible. Hopefully I will have a fully functional car ready for the first actual race

[CAEdevice]

I am only around 7900N and with balance issues

[TalnoRacing]

I would like to ask for advice regarding cooling differential pressure. I am currently at 14.98Pa.m2 (which results in 56% engine power), but I am unsure as to the best way to approach fixing this and getting it to at least 20Pa.m2.

Do I try and improve airflow to the inlet or reduce pressure behind the outlet? Or do I simply increase the size of the inlet?

[LVDH]

Quite happy with my results: they are in line with my 10000N target (actually, i'm 45N short).

Oh no, he did it again.
So we can all spend the season trying to catch him. My car is a bit short but at least cooling is not an issue. But as it is a bit off balance. It is time to see some race results.
Is there any chance you can do it like last year and remove the downforce again from race to race?

[RicME85]

Seeing as we are sharing....

The drag and downforce performance predicted by the simulation are:

Total drag: 1658.09 N
Front wing(s) drag: 347.23 N
Rear wing(s) drag: 445.43 N
Drag coefficient - Cd: 0.80
Drag area - Cd.A: 1.38 m2
Total Downforce: -5745.69 N
Front wing(s) downforce: -1265.35 N
Rear wing(s) downforce: -2312.37 N
Downforce coefficient - Cl: -2.78
Downforce area - Cl.A: -4.79 m2
CoP of downforce: 2.454 m along streamwise (Y) direction from Y = 0.00 m.
KVRC Only: Corrected CoP of downforce: 2.052 m along streamwise (Y) direction from Y = 0.00 m.
The pressure at intake and exhaust are:

Engine intake, Area: 0.016m2 - Compliant
Surface integral of pressure: 5.61 Pa.m2
Engine exhaust, Area: 0.010m2 - Compliant
Surface integral of pressure: -5.85 Pa.m2
Cooling intake, Area: 0.096m2 - Not compliant !!!
Cooling exhaust, Area: 0.081m2 - Compliant
Differential of surface integral of pressure: 12.56 Pa.m2

[variante]

I would like to ask for advice regarding cooling differential pressure. I am currently at 14.98Pa.m2 (which results in 56% engine power), but I am unsure as to the best way to approach fixing this and getting it to at least 20Pa.m2.

Do I try and improve airflow to the inlet or reduce pressure behind the outlet? Or do I simply increase the size of the inlet?

I was wondering the same. Increasing pressure on the inlet and decreasing on the outlet is obviously the right way to go.
But how to achieve that?
Well, for Option 1 we have a given mass flow (3m^3 of air each second). Unless i'm missing something, increasing inlet surface should decrease the velocity of the air forced through, therefore increase its pressure. The opposite for the outlet.
That might not be enough... To increase pressure on the inlet i'm not just ducting freestream air on the surface (which is fast, thus translates its energy into a good amount of high pressure when meeting an obstacle, like the inlet) but i'm also using turning vanes to force air into the inlet. Now, those solutions should work because the inlet doesn't accept more than 3m^3/s, so the energy of the airflow in excess is translated into high pressure and the flow itself is deviated elsewhere.
Does it make sense?

Is there any chance you can do it like last year and remove the downforce again from race to race?

This year i'm focusing in removing airflow from the engine.

Seeing as we are sharing....

Well, you've shared impressive numbers this round, especially considering the very small window of time you had to develop the car.

[RicME85]

Thanks Jacopo.
I have a completely new concept in the works (upper surfaces - I think the floor is working well) that I will try out between now and the first official race.
As you say though, the figures arent too bad considering the time I spent on the car, will be interesting to see figures of other cars that have used the supplied bodywork (the main body as my submission had different front wheel pod/fenders).

[RicME85]

Thought I would dig out the results of the last iteration of last seasons car for comparison.

2015 Race 6 Car:

Drag: 1557.67 N
Drag coefficient - Cd: 0.75
Drag area - Cd.A: 1.30 m2
Downforce: -5619.42 N
Downforce coefficient - Cl: -2.71
Downforce area - Cl.A: -4.69 m2
CoP of downforce: 1.552 m along streamwise (Y) direction from Y = 0.00 m.
KVRC Only: Corrected CoP of downforce: 1.601 m along streamwise (Y) direction from Y = 0.00 m

2016 Pre-season Test Car:

Total drag: 1658.09 N
Drag coefficient - Cd: 0.80
Drag area - Cd.A: 1.38 m2
Total Downforce: -5745.69 N
Downforce coefficient - Cl: -2.78
Downforce area - Cl.A: -4.79 m2
CoP of downforce: 2.454 m along streamwise (Y) direction from Y = 0.00 m.
KVRC Only: Corrected CoP of downforce: 2.052 m along streamwise (Y) direction from Y = 0.00 m.

I think it could be a good base if the other concept I have doesnt work out. Some fine tuning of wing profiles should help with the efficiency.

[machin]

I would like to ask for advice regarding cooling differential pressure. I am currently at 14.98Pa.m2 (which results in 56% engine power), but I am unsure as to the best way to approach fixing this and getting it to at least 20Pa.m2.

Do I try and improve airflow to the inlet or reduce pressure behind the outlet? Or do I simply increase the size of the inlet?

I was wondering the same. Increasing pressure on the inlet and decreasing on the outlet is obviously the right way to go.
But how to achieve that?
Well, for Option 1 we have a given mass flow (3m^3 of air each second). Unless i'm missing something, increasing inlet surface should decrease the velocity of the air forced through, therefore increase its pressure. The opposite for the outlet.
That might not be enough... To increase pressure on the inlet i'm not just ducting freestream air on the surface (which is fast, thus translates its energy into a good amount of high pressure when meeting an obstacle, like the inlet) but i'm also using turning vanes to force air into the inlet. Now, those solutions should work because the inlet doesn't accept more than 3m^3/s, so the energy of the airflow in excess is translated into high pressure and the flow itself is deviated elsewhere.
Does it make sense?

As expected.. this is going to be the real challenge for this year... for the class B cars we have the added difficulty that we can't increase the size of the inlets which would otherwise have been my first solution...

I too am using "barge boards" in an attempt to control the flow into the inlet, but the results tell me that too much air is either going over the top of the front suspension cover or underneath the floor, so my plan is to change my front suspension cover to encourage more air "through" the front of the car rather than over the top....

When I get some time I plan to update my own thread with my results.

[CAEdevice]

Well, honestly I would ask for smaller inlets if possible. It is all about flow direction and total pressure (edit: with "total" I mean "dynamic" pressure).

About the outlets: to avoid problems, my advice is to put them just over the diffuser, in the low pressure region behind the car.