Project-1: Powertrain for aircraft in runways
PART B :
Solution 6.A : We are asked to calculate the force and power required to push / pull an aircraft by a towing vehicle, with necessary assumptions.
To calculate the force and power , we should initially find all the forces acting on the body .
The forces acting on the Vehicle are :
( a ) . Rolling Resistance Force
First we calculate the Rolling Resistance force of the Aircraft , which can be represented by the equation :
Fr = ur * m * g
where ur = Coefficient of Rolling resistance = 0.02
m = Mass of the aircraft in kg = 65000
g = Acceleration due to Gravity = 9.8 m/s^2
Fr = 0.02 * 65000 * 9.8
= 12740 N
= 12.74 kN.
we calculate the Rolling Resistance force of the Towing Vehicle , similarly by
Fr = ur * m * g
where ur = Coefficient of Rolling resistance = 0.01
m = Mass of the Towing Vehicle in kg = 10000
g = Acceleration due to Gravity = 9.8 m/s^2
Fr = 0.01 * 10000 * 9.8
= 980 N
= 0.98 kN
( b ) . Aerodynamic Drag
Aerodynamic drag force acting on the vehicle can be caluclated by
Fd = 1/2 * Cd * P * A * v^2
where Cd = Coefficient of Drag
P = Density of the Air
A = Frontal Area of the Vehicle in m^2
v = Velocity of the vehicle
We will be calculating Drag force only on the aircraft , since the Drag acting on the towing vehicle will be negligible compared to that of the aircraft , which makes very little or no difference .
So Drag force = 0.5 * 0.25 * 1.25 * 20 * (5^2)
= 78.125 N
= 0.078125 kN .
Now we calculate the total force by adding all these forces , Rolling resistance Force of Aircraft and Towing Vehicle and the Aerodynamic Drag
Total force acting = 12.74 + 0.980 + 0.078125
= 13.798125 kN .
Power can be calulcated by :
Power = Force * Velocity
= 13.798125 * 5.
= 68.99 kW
So the Power required for the Towing vehicle to pull the aircraft is 68.99 kW .
The simulink model of the Force Acting on the Powertrain is as follows :
All the calculations are shown seperately in the simulink model , and then finally the forces acting on the system and the Power required to pull the aircraft is also displayed .
SOLUTION 7 :
A. We are asked to design an electric powertrain with type of motor, it’s power rating, and energy requirement to fulfill aircraft towing application in Simulink. Estimate the duty cycle range to control the aircraft speed from zero to highest. Make all required assumptions. Prepare a table of assumed parameters. Draw a block diagram of powertrain.
Weight of the Aircraft = 65000 kg
Coefficient of Rolling Resistance of Aircraft = 0.02
Coefficient of Rolling Resistance of Towing Vehicle = 0.01
Weight of towing vehicle = 10000 kg
Density of Air = 1.25 kg/m^3
Velocity of the Aircraft = 18 km/hr = 5 m/s .
Coefficient of Airdrag of Aircraft = 0.25
Radius of the Wheels of the towing vehicle = 0.6 m
Gear ratio = 11
From the previous solution we have calculated th force and power
So the Force acting on the Vehicle will be : 13.798125 kN .
Power required by the Towing vehicle to pull the Aircraft = 68.99 kW
Now we calculate the torque required by the wheels of the vehicle to Pull the aircraft :
Torque = Force * Radius of the wheels of Towing Vehicle / Gear ratio
= 13.798125 * 0.6 / 11
= 0.752625 kNm
Then we move on to the calculation of the energy required and the battery capacity :
Energy requirement of the towing vehicle to pull the vehicle :
For this we assume that the time taken for pulling the aircraft by the Towing vehicle will be , = 25 minutes
So energy = Power * Time
= 68.99 * 15 / 60
= 17.2475 kWh
So the Energy required for Towing the vehicle once is 17.2475 kWh.
Motor selection calculation :
Type of the motor = Permanent Magnet Synchronous Motor
Model NUMBER
The motor specifications are given in the table below :
Here the efficiency of the motor is assumed as 95 % .
DUTY CYCLE CALCULATION :
Here , Duty cycle = Output Power / Input Power
Here Output Power = 68.99 kW.
Rated Power of Motor = 80 kW
Calculating duty cycle we get
D = 68.99 / 80
= 0.86235
So the duty cycle of this particular powertrain is 86.235%
Block Diagram of a Powertrain of an EV :
Powetrain consists of all the enrgy sources and the energy converters required for the efficient propulsion of the system . It has a battery pack in it, which contains the battery modules arranged according to the requirement of the vehicle .Then there is a cruise controller which takes feedback and is fed back into the engine transmission system .Electric converters are used that iws the DC-DC CONVERTERS SO THAT THE MOTOR DOESNT run only at the rated speed.