1. ## Ricardo Inputs

1)How do you measure or what input do you give to the combustion duration (10-90%) in Ricardo SI Wiebe Model?
2)Also how do you determine the speed of the turboshaft? If say we want to run cases from 1000 -12000 RPM what is the procedure to determine what turboshaft RPM has to be used at each of these cases?

2. Ritwik,

1. Not sure. Plug some numbers in/read the tutorial and find out.
2. Turbo speed is determined by a number of factors. What turbo are you using? What do your compressor and turbine charts look like? What exhaust flow control method are you using? Do you have variable geometry? Are you running anti-lag? Do you have a turbo speed sensor to check whether it's actually spinning where it should be? Do you know what engine modifications you need to do to run a turbo successfully? Some of these questions can be answered by selecting a turbo properly and seeing how shaft speed relates to intake air mass flow and desired pressure ratio. More importantly, you are an inexperienced team and correct me if I'm wrong but you don't appear to have collected much in the way of results. Have you finished a full event, placing reasonably in all dynamic sub-events? If not, a turbo will not help you. It will do the opposite.

3. Adding to what Jay said:

2. I don't really know how Ricardo Wave does it, but the simulations I know and work with will calculate turbo speed itself (with the help of all the data Jay mentions, which you have to input - again, read the tutorials, this can be VERY tricky sometimes to get it right). So you only have to give the software an INITIAL turbo speed for the given case. Then, it helps to play with the turbo inertia. It can help to set this to very high values for the first iteration steps, so that the initial speed will be maintained while the other simulation parameters come to realistic values. Then set it to unrealistically low values for a few steps, so that the turbo speed "adjusts itself" to correct values faster. Then back to a realistic value.

Then compare it to dyno results and find out that the simulation gives you a completely wrong picture... It is really, really MUCH work to get a simulation model which actually really predicts what the engine will do, especially with a turbo.
Be happy that you don't have variable valve timing...

4. We have all the maps and answers to all the questions above. However the point of asking the query was that in Ricardo you can't specify the turboshaft rpm at each RPM of the engine. There are 3 options called balanced,fixed speed and geared off crankshaft."Balanced" is the initial turboshaft speed for that RPM. "Geared off Crankshaft" is engine RPM multiplied by gear ratio which is specified by user."Fixed Speed " is user entered fixed simulation speed of turboshaft.So the problem is that although we approximately know the turboshaft RPM at different engine RPM's we don't know how to input that into the software.Nothing can be inferred from the tutorial.

5. You don't know the turboshaft speed at different RPMs because the turbo speed is independent of engine speed!
The turbo can still be running at high RPM with the engine stopped!

Pat Clarke

6. Originally Posted by Pat Clarke
The turbo can still be running at high RPM with the engine stopped!

Pat Clarke
But wouldn't that be due to the momentum of the shaft and not due to any torque on the shaft?Anyways my question remains how am I supposed to input that parameter in RICARDO. I am sure there are teams with turbos . I would request them to help me here.

7. Originally Posted by ritwikdas18
Anyways my question remains how am I supposed to input that parameter in RICARDO.
Simple: You don't input that parameter.
As you said, with your "balanced" option, you can give the software an initial turbo speed. The software will then calculate the "actual" turbo speed for the given case (RPM) and the given "hardware setup" (engine and turbo data, cam timing etc.).

Where would you want to take the turbo speeds you want enter into the software from?
Have you measured the actual turbo speeds on an engine dyno? If yes, was it a transient dyno pull, or static for a while at certain RPMs? Does your ignition timing match the ignition timing that Ricardo calculates? What about wastegate opening, what do you do in "real life" (wastegate opening based on a RPM/TPS/MAP-map, or purely dependent on MAP, or RPM/TPS/MAP plus correction map for post restrictor pressure...) - and what does Ricardo do? And so on, and so on.
This is what Pat Clarke said, there is no certain turbo speed at a certain RPM, it depends on a lot of things.

If you really have measured actual turbo speeds, well, all the better, then you can verify your simulation results better.

8. Hello Ritwik,

1) get the engines burn duration you need to run a pressure indication system and calculate the burn rate from the sensed pressure signal. This will however require a very expensive indication system most teams dont have access to. In the end you´ll probably end up using some reasonable estimations, and adjust the parameter to fit your engine imep. As long as you use reasonable estimations it is not a very important factor if you are only looking for a relative comparability when adjusting your gas exchange.

2) The turbo speed is determined by your intake system and your desired charge pressure. I am not familiar with wave, however the only useful way is to use a wastegate controller which adjusts the wastegate throat diameter to control the turbo speed and hence the pressure ratio of the compressor. This method will also result in the correct turbine back pressure which you dont get if you simply lock the turbo to a certain speed and dont actuate the wastegate.

9. Originally Posted by Jan_Dressler
Simple: You don't input that parameter.
As you said, with your "balanced" option, you can give the software an initial turbo speed. The software will then calculate the "actual" turbo speed for the given case (RPM) and the given "hardware setup" (engine and turbo data, cam timing etc.).
We are not using a wastegate(After analysis we have understood that we don't need to).You are right ,In the tutorials , they have given the software an initial turbo speed at each RPM (initial turbo speed being same for a range of bit higher end RPMs (3000-5000 RPM in the simulation case)). I don't have a clue and neither can it be inferred as to how they got to the initial RPMs for different turbospeeds.I know that's the right thing to do, but how do we calculate the initial turbo RPM at each RPM of our simulation? Approximate numbers will do.

10. Originally Posted by ritwikdas18
We are not using a wastegate(After analysis we have understood that we don't need to).
Free-floating huh? This is not going to go well. I highly suggest diverting your resources from modelling to physical testing so you can quickly learn about pulse flow and turbine matching with single cylinder engines.
You are right ,In the tutorials , they have given the software an initial turbo speed at each RPM (initial turbo speed being same for a range of bit higher end RPMs (3000-5000 RPM in the simulation case)). I don't have a clue and neither can it be inferred as to how they got to the initial RPMs for different turbospeeds.I know that's the right thing to do, but how do we calculate the initial turbo RPM at each RPM of our simulation? Approximate numbers will do.