Assignment 7

AIM :- To build a Fast Running Model (FRM) by using FRM builder approach.

OBJECTIVES :-

The main objectives of this challenge are-

• Build a FRM model by using following configurations
  • Bore = 102 mm, Stroke = 115 mm, CR = 17
  • Of cylinder = 6
  • CI engine, Twin scroll turbine, GT controller
• Show the required plots and data.

THEORY AND INTRODUCTIONS :-

FRM is a fast running model. It is a fully physical model I.e. dynamic in nature and designing is fast.

If there have not use fully physical approach then we can use mean value approach. The basic difference between FRM and mean value is that Mean value is a Equation base approach and FRM is Fully physical model and it input base approach. FRM model is a very fast approach therefore it is use in hardware loop approach I.e. it is a mathmatical approach and electrical approach.

If we use total model to sence the signal in ECU then that not possible because sence of signal by

using total model, it should be very difficult. Therefore we can use FRM method or mean value method. It reduces solver time which is very important factor. As a mean value is a equation base approach we can not capture the incylinder pressure beacause there need lot of data, lot of statisics …etc. So, in place of Mean value approach we use FRM model, which has some basic benifits such as follows-

Fast running Model (FRM) :-

FRM’s are able to achieve such fast run times by two means-

1. Increasing the simulations time step size
2. Decreasing the number of calculations per time step

GT power is solves the Navier stroke equations using some numerical methods like Neuton Raphson methods. As this is numerical solution it may diverge and not getting the solutions which is the exact solutions. So for that have some approaches like Implicit approach, Explicit approach. In Navier stroke equation use explicit approach where time and discritization length is very important. Each and every components inside the GT power we get the descritization length and divide that components to this small length and there is a thumb rule that inlet diameter is a 0.4 times and exhaust diameter is 0.55 times, this is all about “dx” and “dt” is -

Courant number is ensure that solution not be diverged, the ratio of dx/dt with the limit of ratio, once I will get that values I will use that in Numerical solutions. By this we can create detail model and by using this detail model we can calculate FRM. It have two approaches as-

1. FRM converter (Conversion of detailed model to FRM)
2. FRM builder (Building FRM model using FRM tool)

Some examples of applications that are ideal for FRMs are:

• ECU Modeling (including HiL) – where a fast-running and transient-capable engine model is essential for optimizing ECU strategy
• Engine + Drivetrain/Vehicle – where accurate torque pulsations are key for optimizing drivetrain design and strategy
• Vehicle Thermal Management modeling, where the engine provides the heat to the cooling system, and the cooling system behavior feeds back into the engine performance predictions (great for simulating off-ambient conditions)
• And many more.

1. Model selction :-

“File -> Tutorials -> Engine performance -> 09-Fast running model -> step8.gtm”

2. Geometry :-

This model demonstrates a turbocharged SI engine with a semi-predictive intercooler. The model runs at steady state engine speeds with wide open throttle (WOT). Here have single volume, which replace by multiple volume. It is called as a fast running model.

3. Engine type :-

Here have two types of engine, out of them 6-cylinder engine choose.

4. Architecture type :-

Currently only two types of engine configurations available according to fuel use. Out of them select Compression ignition engine

5. Control logic type :-

Here have two controller, out of them select GT-SUITE controller.

6. Cylinder geometry :-

Bore = 102mm Stroke = 115mm Compression ratio = 17.

7. Turbo type :-

Here have two types of turbo, out of them select Twin scroll turbo.

8. Main model :-

In main model have everything I.e. turbocharge, FRM intake, FRM diesel, after treatment model and controller model. Here have recieve signal controller to recieve the signal from various part and show the EGR controll. Here have also send signal, it’s the best way to send the signal to different different part and recieve as well.It reduce the complexity of model.

9. EGR Effectiveness model :-

Effectiveness = Actual temp drop / Maximum temp drop

Effectiveness is the function of surface area and air flow rate. EGR cooler is not cool by cooler but it is cooled by Engine cooler. EGR can not cooled more because of, EGR is a exhaust and in exhaust there have soot and soot will go and stick to the wall and results is to damage the wall.

10. FRM exhaust model :-

Air takes from enviornment and goes to the airbox and airbox is a simple volume and finaly intake goes to the compressor inlet.

11. FRM intake model :-

Here fuel flow from End inlet to Air box by intake pipe-1 and it goes to intake port by Intake pipe-2.

12. FRM diesel model :-

As this is twins scroll model each three cylinders are attached with the exhaust manifold and all six cylinders are attached with the Intake manifold, and it have two entries.

13. FRM EGR control model :-

Here have EGR model which is use in heavy duty. Use of EGR is reduce the incylinder temperature. Therefore the NOx formation takesplace. In diesel engine NOx and soot is the prolem. EGR controlls generally closed loop or open loop strategy. In closed loop strategy BSFC function is prefared. EGR is a function of air flow rate.

EGR = Mass of EGR / Total air flow rate

14. FRM EGR HP model :-

Here throttle is used to control the air flow rate. Throttle is used in gasoline engine and in diesel engine we don’t use throttle.

15. Hystorisis model ;-

Here all the connection linked with the multiswitc, which is the main part of the body to control the flow.

16. IC Effectiveness model :-

Here have intercooler and this is use to cool down the high exhaust gasses. Effectiveness is nothing but the chargercooler is cooled by ambient air, chargerecooler is placed infront of radiator.

Effectiveness = Actual temp drop / Maximum temp drop

17. Turbo model :-

Here turbine connector are coming from FRM EGR control model. Turbine works on exhaust kinetic energy and coupled with compressor by using shaft. Intercooler reduce the temperature and increase the density.

18. Case set up :-

Here have different defferent load positions from zero to 100%. At 0% throttle valve is fully closed while at 100% throttle valve is fully open. Orange colour shows here that value have formula and we can not put any formula there. We can BMEP also adjust here for torque availability.

19. Engine geometry :-

Bore = 102 mm Stroke = 115 mm Connecting rod length = 201.2 mm

Compression ratio = 17.

All basic data are given here.

20. Engine operating conditions :-

Here I calculated two casses for engine speeds are 4000 & 3500 rpm. Also given combustion start angle and injection start angle.

21. Engine performance predictions :-

As engine speed decreases Brake power increases and Torque value also increases. Supply of air flow and fuel flow rate decreases also BSFC consumption decreases as mass of fuel decreases.

22. Engine performance (Fuel Energy basis) :-

Here given Fuel, Usable, Brake, Friction, Exhaust, Heat transfer value on the basis of energy and %of fuel energy.

23. Key cylinder predictions :-

F/A ratio = 0.057 Lambda = 1.225 Fuel mass = 108.8mg

Maximum pressure = 130.01 bar Maximum temperature = 1962k.

24. Engine MEP, Torque & power :-

MEP = 18.6 bar Torque = 834.4 Nm Power = 349.8 KW

25. Compressor/Turbine/Pump/Fan :-

The speed of compressor and turbine, both have equal I.e. 110478 rpm

For compressor,

Static pressure ratio = 2.54 Normal pressure ratio = 2.45 Power = 54 KW

Mass flow rate = 0.38 kg/sec Efficiency = 61.8 %.

For turbine,

Static pressure ratio = 2.31 bar Normal pressure ratio = 2.31 bar Power = 53.9 KW

Mass flow rate = 0.28 Kg/sec Efficiency = 72%.

26. Stability table :-

Here have given orignal value of each cylinder, it’s index, time/theta and Vapour fraction values, Also given case elapsed time and Final elapsed time.

27. Compressor efficiency :-

Here plot is pressure vs mass flow rate. Different efficiency given here. Compressor efficiency comes under safer zone here, it means we can design such types of FRM.

28. Controller Dinjector :-

Here, have the smaller difference between actual and output values. BMEP shows smaller gap and within a short time it is converged. It is main use in PID contriller. Here directly use PID controllerwhich is avialable in the GT power.

29. Controller :-

Here showing boost pressure controller values. Here have the larger difference between Actual and output values as shown in the above plot.

30. EGR controller :-

Here not requirment of EGR values, and thats why here showing less than one.

31. PID controller :-

No PID values are intersect with each other. Target value is along X-axis, Actual value is along Y-axis and Output values have specific values I.e. 0.25 which is parallel to X-axis.

CONCLUSIONS :-

The conclusions from above challenge are-

1. There have one inlet and one outlet
2. Reduce the complex model into simple model by using wireless devices.
3. Fuel injector directly connected before inlet port.
4. Intercooler is used to cool the engine.
5. Turbine connected to the compressor by using shaft.
6. Recieve signal control FRM model use to recieve the signal and send to the engine by using FRM EGR controller.
7. Adjust the load, BMEP and engine speed according to required power and torque.
8. We putted the input values are exact that’s why we get compressor efficiency in safer zone.
9. Target value, Output value and actual values are parallel to each other.

In this way, I explore the tutorial number 9 and build FRM model. FRM model is really helpful to get faster solution and changing complex geometry to simple geometry.