Week 6 - Data analysis

• Descriptive Analysis.
• Diagnostic Analysis.
• Predictive Analysis.
• Prescriptive Analysis.

The data file given consist of various parameters of an engine. We have to calculate the below parameters

1] Work done by the engine is obtained by calculating the area under the P-V diagram

2] Power output of the engine is given as below

n - Number of cylinders of engine, RPM - engine speed in minutes,W_Out - Work output by the engine

3] Specific Fuel Consumption(SFC)

SFC = mass of fuel consumption / Engine brake power = FC / P_b

PROCEDURE :

To solve the above given problem statement, following procedure is followed:

1. Using a python program initally the name of the data file is taken as an input from user and checked whether the file is present or not, if the file is not pressent then the program is terminated.
2. Then the file is opened and data is read line by line and stored.
3. The name of parameters, their units and their coulmn number are stored as an array and dispalyed in form a table for the user to select the required columns.
4. Then the column no for independent parameter (x-axis) and dependent parameter (yaxis) is taken from user and the values of those clumn are extracted from data file and further plotted.
5. From the PV diagram Area under the P-V curve is calculated using the Trapezoidal Rule As we Know An area under the P-V diagram is equalto Work Done
6. In the next step Work was done that is calculated is used for calculating the power output

Power = Work *Speed

7. Specific Fuel Consumption = Mass of Fuel Consumption per hour/Power Developed in KW

Code :

# Python code for data analysis

import matplotlib.pyplot as  plt
import numpy as np
import math
from numpy import trapz

print('General Intrustions')
print('Please make sure that the CONVERGENCE data file is saved in the same directory where python file is saved')
# file name  = input
file_name = "engine_data.out"

# Compatability check
try:
	data = open(file_name,'r')
	print('\nData file is sucessfully opened')


except FileNotFoundError:
	print('\nPlease enter a valid file name')


line_count = 1
for line in data:

	if line_count==3:
		parameter=line.split()
		columns=len(parameter)
		print('\nThis CONVERGENCE file contains following data which is derived from I.C Engine Simulation')
		print('It has total %d Data Columns' %(columns-1))


		for C_no in range(1,columns):
			print(C_no,line.split()[C_no],line.split()[C_no])

		break
	line_count=line_count+1

print('\nChoose any Two parameters from above')
print('Enter a number corrosponding to parametr 1 to 17\n')
x=int(input("Enter x-axis parameter : "))
y=int(input("Enter Y-axis parameter : "))

x_data=[]
y_data=[]

line_count=1
for line in open(file_name,'r'):
	if line_count==3:
		x_label = line.split()[x]
		y_label = line.split()[y]


	if '#' not in line:
		x_data.append(float(line.split()[x-1]))
		y_data.append(float(line.split()[y-1]))


	line_count=line_count+1



file_name=y_label+'vs'+x_label+'.png'

plt.figure()
plt.plot(x_data,y_data)
plt.xlabel(x_label)
plt.ylabel(y_label)
plt.title(y_label+ ' vs ' +x_label)
plt.savefig(file_name)
plt.show()

if x==8 and y==2:
	RPM=1500
	Area=np.trapz(y_data,x_data)
	Workdone=Area*1000
	Power=2*math.pi*RPM*Workdone/60
	Fuel_per_stroke=20*1e-6
	Fuel_per_sec=Fuel_per_stroke*RPM*(0.5/60)
	Fuel_per_hour=Fuel_per_sec*3600
	BSFC=Fuel_per_hour/Power

	print('Area under the P-V diagram(Workdone) :',Workdone,'KJ')
	print('Power output of the engine :',Power,'KW')
	print('Specific Fuel Consumption :',BSFC,'g/KWh')

Explanation:

1. Initially, the required modules are imported.
2. File name is taken as an input from user and, to verify the user file with engine_data.out file, if command is used.
3. The Using a for loop every line of file is read line by line and the lines with '#'not include to read data and are appended to an array named 'column_1 & column_2’.
4. Using a for loop the extracted column no and names are displayed for user and asked to make a plot.
5. Then the values of the column selected by user are extracted and stored in an array and further plotted on a graph.
6. For basic performance calculation the values of pressure andvolume column are extracted and using the 'np.trapz(P,V)' command, area under the PV diagram is calculated which also is the Workdone.
7. Converting the given speed of 1500rpm into rps the power output of the engine is calculated and further the specific fuel consumption of engine is calculated.
8. All the values calculated are displayed on the screen for the user.

RESULTS :

Output Screen and Plots :

If the user enters a valid file name & for parameter 8 , 2

plot obtained-

If the user enters a valid file name & for parameter 1 , 8-

plot obtained-

If the user enters a valid file name & for parameter 1 , 12-

plot obtained-

CONCLUSIONS:

1. The data from the output file was read successfully and the plot required as per the user need was made.
2. The performance calculations were done and displayed successfully.