marine engine propeller marine engine propeller me 270 dr. granda dong-un sul
TRANSCRIPT
Marine Engine Marine Engine PropellerPropeller
Marine Engine Marine Engine PropellerPropeller
ME 270 ME 270
Dr. GrandaDr. Granda
Dong-Un Sul Dong-Un Sul
Marine Engines
Temporary engine
N60ENTM40: 400 HP
An old marine engine manufactured by
Gray Company
Problem Statement
• A marine engine connected to a propeller through gear is shown below.
• The mass moments of inertia of the flywheel, engine, gear 1 and 2 and the propeller (in kg-m^2) are 9000, 1000, 250, 150, and 2000, respectively.
Schematic
Objectives
• By using the Matlab, obtain the transfer functions and state form and run a test to draw reasonable outputs
• Build a bond graph of the system in CAMP-G• Find natural frequency of the system • Compare the results from Matlab with the
ones in a reference book• With another software, find the frequency of
the model as well (i.e. Nastran4D)
3D View
• For better understanding, this model was built in Solidworks.
• This model will transfer to Nastran4D to simulate.
Parts
Initial Bond Graph• Two I-elements
turn out in red which means that there are two derivative causalities in this system.
Bond Graph with derivative causality
Attaching C-element• To eliminate
derivative causality, C-elements are added into the system.
• As C-values get smaller, they can be negligible.
Differential Equationsfrom Matlab
• Number of States 10• dP21=Q25/C25• dQ25=P11/I11*T13x14-P21/I21• dQ24=P11/I11-P23/I23• dP23=Q24/C24• dP19=Q17/C17• dQ17=P11/I11*T13x14-P19/I19• dQ4=SF1-P6/I6• dQ9=P6/I6-P11/I11• dP6=Q4/C4-Q9/C9• dP11=Q9/C9-Q17/C17*T13x14-Q25/C25*T13x14-
Q24/C24
Simulink
State-Space function
Transfer function
Nastran4D Analysis
Frequency derived from Nastran4D
• Flywheel = 3.09E-5 Hz• Gear1 = 2.39E-5 Hz• Engine = 2.45E-5 Hz• Propeller = 1.08E-5 Hz• Gear2 = 1.09E-5 Hz
Conclusion• Nastran4D will be helpful with accurate
values in the system to find the frequency of it.
• However, I failed obtaining the appropriate frequency because the values were not given sufficiently.
• Plus, by using the Matlab, I couldn’t get the frequency of the system because determinant for A matrix became 0.
• I believed that to perform much more accurate analysis of the system more data should be provided.
Simple Model (Alternative approach)
• Schematic• This is the schematic of
the simple model which is equivalent to the system above with 5 mass moments of inertia. J1 can be obtained by summation of mass moment of inertia of the engine, gear1 and gear2. To get the torsional stiffnesses of shafts1 and 2, a shear modulus of 80 x 10^9 N/m^2 for steel is used to find the natural frequency of the system below.
Bond Graph
Differential Equations
• dP11=Q8/C8• dQ4=SF1-P10/I10• dQ8=P10/I10-P11/I11• dP10=Q4/C4-Q8/C8
Simulink
• Based on the differential equation, simulink was built in the Matlab.
A Matrix
• From the Matlab, A matrix was obtained like shown on the left side.
A Matrix with initial values
Calculation by hand
Solution from the book
Comparison(Natural Frequency)
• 1588.46 ± 1503.1483 (book)
• 1588.46 ±1503.147882 (Matlab)
Nastran4D
Nastran4D• Frequency of the system from Nastran4D
with initial values • Mass1 = 7400.00 Kg• Mass2 = 22222.22 Kg
• J1 = 2.8E-5 Hz• J2 = 1.53E-5 Hz
Conclusion• CAMP-G model helps find the natural frequency as it
interfaces with Matlab, which generates A matrix.• The natural frequency calculated by Matlab is very
accurate.• To get right results from Matlab, initial values should
sufficiently be given like the second simple model. • Due to errors taking place for the first model, complicated
one, in some reasons, failure may be unavoidable. • A bond graph will be a very useful tool once engineers
understand how it works. • It helps engineers to save their times and efforts without
setting mathematical equations for the system that they want to work out.
• However, there is disadvantage of it. In other words, no one can guarantee whether the bond graph is correct or not. With the wrong bond graph, all analysis can be useless.
Enjoy your winter break!! Merry Christmas and Happy
New Year!!
Thank you very much!