Vibration in marine diesel engine | 22-23 The Best latest Tutorial on

Vibration in marine diesel engine

Marine diesel engines are some of the most popular machines in the world. They are used in various industries, such as Marine, Power Generation, transport, heating and cooling, and agricultural purposes.

Marine diesel engines produce vibrations that can affect engine performance. You may not be aware of it, but this can significantly impact the engine’s running. However, they can also suffer from some of the most common vibrations. This vibration can cause problems for the engine, such as vibrations in the fuel system, noisy emissions, and instability.

In this blog post, we will cover the various vibrations that can occur in marine diesel engines and help the readers understand them.This blog post will also cover the different vibration dangers that can affect marine diesel engines. We will also help the readers understand the different vibration types and how to avoid them.

There are a variety of factors that can cause vibrations in marine diesel engines. We will go over the different types of vibrations and explain how they can affect your engine.

In this Post on Vibration in marine diesel engine, we will discuss about the following.
1) Essential guidelines for the vibrations.
2) Type of vibrations, and measurement of vibrations .
 
We will also explain the follwing becuause it is the requirement to understand the basics.
1) Acceptable levels of vibrations on the marine Diesel engines.
2) The associated electrical and mechanical components of the engines.
 
Will use the vibration norms and theoretical aspects of Vibrations. Preliminary knowledge of the standard techniques so will also form the base of the post.
 
There could be confusion because of the several vibration acceptable standards. The available standards don’t provide any guidelines for the engine-mounted components. I will also take the reference of following.
1) Past knowledge of my colleagues.
2) my knowledge of 45 years working on marine and industrial engines.
 
The aim of this post is to produce a standard so that will be useful in Diesel Engines vibration.
 
These guidelines will show following.
1) The location of placement of sensors for measuring vibration readings.
2) The interpretation of results.
 
The instructions in this post will be helpful for the readers. to non-technical background individuals becuase of the readability.

What is Vibration in marine diesel engine?

Vibration is motion or mechanical oscillation induceed by forces on a machine.

Types of Vibration

Types of Vibration
Vibration in an engine
  1. Free Vibration
  2. Forced Vibration
  3. Damped Vibration
During the operation of an engine, there is the creation of many types of excitations.
 It is impossible to achieve complete control of vibration in diesel engines due to the-
 engine’s rotating parts and firing and gas pressure.
The designs are too complicated to control the Vibration in marine diesel engine.
from getting closer to the natural frequency-
Following will occur due to the natural frequency nearng to natural vibration. 1) Higher forces. 2) Catastrpoic failure.
 
Different parts of the engine will have different levels of vibration.
 Carry out the vibration checks. at various points and directions in the longitudinal, transversal, and vertical axis.
 
Obtained readings should be normal in each direction. The measurements exceeding the prescribed normal limits-
needs through investigations forthe the  checks, and corrections.

Free /Vibration in marine diesel engine

Free /Vibration in marine diesel engine

The disturbance of body from its position is known as free vibration in marine engine. Free vibration will be affected by the natural frequency.

Forced Vibration in marine diesel engine

An external periodic force produces the forced vibration. The frequency of forced vibration is proportional to the external periodic force.

Damped Vibration in marine diesel engine

In damped vibration the reduction in amplitude will occur in every cycle.

Best Vibration Meters

Electronic Vibration Meter

Viberation Meter 2
Vibration in marine diesel engine | 22-23 The Best latest Tutorial on 16

This is one of the best vibration meters. The features of this meter are listed below

  • Pen type Pocket Size instrument. LCD Display. Compact Size. It is light and easy to carry.
  • It can measure acceleration, velocity and displacement.
  • Simple Two Key Operations. Auto Power Off facility.
  • Acceleration: 0.01-199.9m/s2(peak value). Velocity: 0.01-199.9mm/s (effective value). Displacement: 0.001-1.999mm (peak-peak value).
  • Acceleration Frequency Response: 10 Hz-1 kHz. Velocity Frequency Response: 10Hz-1kHz. Displacement Frequency Response: 10 Hz-500Hz.

Walfront Vibration Meter

image 15

The Vibration Meter, High Accuracy Split Type Digital Vibration Meter is the perfect tool for measuring vibration levels in the environment. With a wide measurement range of acceleration: 0.1~199.9m/s2 peak, it can measure the environment temperature with 2 temperature units (℃ and ℉). The vibrometer gauge adopts piezoelectric acceleration transducer transfer the vibration signal in to electrical signal, analyze the input signals, and show the vibration level.

Basic Theory of Vibration in marine diesel engine

Quote 300x133 1
 
The following three parts constitute the Vibration in marine diesel engine arrangement.
 
1.    Spring for the storage of potential energy
 
2.    A mass (Inertia) for the storage of Kinetic Energy.
 
3.    A damper for the gradual loss the energy.
 
In a Vibration in marine diesel engine system-
The energy alternates between kinetic and potential forms. During each cycle, a damping system loses energy.
 

Amplitude Displacement

Amplitude Displacement

Amplitude

Is the highest extent of vibration measured from the position the position.

Measured from from the position the position.

The RMS value is the most common in measuring the speed values for the rotating machines, and the unit of part measurement is Revolution per minute (RPM).

The physical quantities of amplitude measurement are listed below.

  1. Displacement;- Displacement means the maximum movement of an object from its stable position to exceed position. The unit of displacement measurement is mils.
  2. Velocity;- Velocity is the variation of linera distance with respectto time. It indicates the speed of the measured part’s movement. The unit of velocity is mm/s or ips ( inch per second)
  3. Acceleration;- Acceleration indicates the speed of change of velocity of a measured point.

Frequency

Frequency Formula

Frequency is the reiteration of vibration. The measurement unit of frequency is HZ.

Frequency Formula

Frequency formula

Damping

Damping reduces the degree of oscillation in a substance or of an element mechanical or electrical device.

which reduces the degree of oscillation is Damping.

Formula of Damping

Damping
Formula of Damping

Natural Frequency

The frequency at which a system continues to vibrate under excitation is

Natural frequency.

Resonance

If the two objects are vibrating in the same frequency the one object will force the second object in to a vibration motion is known as esonance.

Vibration Measuring Specifications

Engine Manufacturers recommend the following Parameters for vibration measurement.

. Displacement measurement;- is applicable for measuring frequency below 30 Hz and below.

Velocity measurement;- Is suitable for measuring the frequency between 10 -300 HZ.

International Standards

Listes below are the available international standards for the measurement of vibrations .
 
ISO 8528-9;- Evaluation of mechanical Vibrations
ISO 10816-6;- for the reciprocating machines above 100 KW rating
ISO 8528-9;- is about the basic knowledge of measuring the vibration and measuring points on an engine.
As per the standard, measure the 0 Temperature and the rated power temperature. The specified Vibration level for the Internal Combustion Engine is, between 2 HZ to 300 HZ. For the whole generator with the system, measurement should be 2HZ to 1000 HZ.
 
  1. ISO 10816-6;- This standard is applicable for engines above 100 KW. As per this standard, the vibration level should be 2 HZ to 1000HZ. 

Vibration Measurement Locations (Points)

Viberation measurements

Vibration in marine diesel engine

  1. Drive end ,
  2. Engine centre,
  3. Non-drive end of crankshaft.

Take the measurement at the working temperature ofthe engine..

Measure the severity of the vibrations as the RMS value of
displacement, velocity, and acceleration

Measurements

Check points
Vibration in marine diesel engine
Measure the vibration on different points on the Engine as per the above picture.
Measure the Engine Pumps and filters.

Component directions

The crankshaft will be in the longitudinal direction for the measurement of vibration at the engine.

The turbocharger will be in a longitudinal direction during the measurement of vibration at the turbocharger.

Vibration Damper

A vibration Damper is a device fitted on thenon-drive end.  Vibration damper eliminates the torsional vibration stresses.
  Vibration Damper reduces the torsional vibration from the peak amplitude

Torsional Vibration Damper (spring and oil dashpot type viscous Damper)

VD
 
Damper also have two round masses with a pack of sleeve springs at the joining surfaces.
Spring space is full with oil through connected grooves.
The driving part mounts with the shaft ad is an integral part of the vibrating shaft.
The design of driven mass will tend to oppose the vibration of the driver.
The movement of the upper concentric mass is normal and even with the engine rotating mass.
There is a disadvantage of using oil in this type of damper.
The absorption of vibration energy during the damping process will heat the oil. Hot oil will lose viscosity resulting in dropping in damper efficiency

Silicone Damper

silicone vd
Vibration in marine diesel engine
This design of damper uses silicone in a self-contained unit instead of oil.
The damper consists of a lightweight flywheel casing ‘A,’ which fits at the free end of the crankshaft. Within the Flywheel rim casing. There is A loose floating mass ‘B.’ 
The space between the floating mass and the case has the filling of silicone fluid. Due to the higher viscosity of silicone fluid, there is very little change in viscosity.
The inertia of Mass ‘B’ with silicone viscous drag effect will oppose the casing vibration.
The viscous shear force will absorb mass A, and mass B will absorb the largest vibration energy.
Mass B will maintain the uniform motion by its inertia.

Causes of Vibration

Listed below causes are the critical causes of the
linear or torsional vibrations in Diesel Engines and generating sets.
 
1.    Misalignment of Prime Mover and the Alternator.
 
2.    If there is an unbalance in the Engine, coupling, Vibration damper, and Alternator rotor components. Unbalance due to the because of conventional unbalance-
Not the attribute of Engine and combustion forces.
 
3.    Structural mass and rigidity combinations are creating resonance.
 
4.    Engine Firing Cylinders attempt to create a twist in the rotor.
 
5.     Misfiring in cylinders.
 
6.    Heavy forces developed during the combustion process.
 
7.    Unbalance in reciprocating parts.
 
8.    Electromagnetic forces.

Harms of Vibration in marine diesel engine

Vibration in an engine is most unwanted for the following reasons.

1.    Increases stress

2.    Addition in wear of parts

3.    Increases sound levels

4.    Excessive material fatigue

5.    Loss in energy

6.    Increase in bearing loading.

All the above factors will result in failure and breakdown in an Engine

Remedial action for reducing the Vibration in marine diesel engine

Listed below is remedial action so as to reduce the vibration in Diesel Engines.
 
1. Correct the misalignment of the Engine with the driven unit. like generator or propeller.
 
2. Check the Anti-vibration mountings for the proper height. Correct the same if found irregular.
 
3. Periodical checks of Engine performance test. Correct the abnormal observations from the EPD readings.
 
4. Check the flexible connections between engine and system pipes and fittings.
 
5. Never allow the machine to run at a critical speed.
 
6. Carry out the periodical checks of tightness of foundation bolts.
 
7. Analyse the condition of the alternator bearing. Replace the bearing if there are symptoms of –
bearing getting overheat and abnormal sound during the operation.

Conclusion (Vibration in marine diesel engine)

I have written the post in a easy lengauage so as to be the easy follow guide for students. Beacuse the write ups written earlier and in the recent posts are not clear but this post is diffrent.

I sincerely hope that the post on Vibration in marine diesel engine has been useful to the readres becuase the post is very simple and to understand.

Vibration due to Defects in Diesel Engines

Improper Tappet Clearance

Maintaining Valve clearance of diesel engines as per the OEM set values is essential. Valve clearance affects combustion and opening and closing of valves. Improper valve clearance will lead to severe defects. Excessive valve clearance will result in the valve’s late start and early closing.

The excessive valve clearance in the inlet valve will result in insufficient air supply to the combustion chamber. Insufficient air for the combustion will cause poor combustion leading to a low compression ratio, less power, improper combustion, less fuel economy after burning, and high carbon deposits inside the combustion chamber.

If an engine continues to run with excessive inlet valve clearance will result in power loss. A piston seizure may occur due to sticky piston rings with high carbon deposits.

Excessive valve clearance in the exhaust valve will lead to poor scavenging followed by knocking, heavy power loss, and high temperatures will lead to catastrophic failure of the Engine. The above phenomenon will severely impact the valve driving mechanism, causing heavy vibrations in the Engine.

Piston Slap

Engine power, reliability, durability, economy, and emissions are highly influenced by the tribological conditions of the cylinder liner and piston rings. The generation of engine noise and piston slap takes place by the piston mechanism. Piston slap is the primary source of transversal vibration in Diesel engines.

 Harsh engine conditions are created due to the high piston speed. Under the condition of the boundary lubrication due to the contaminated lubricating oil and high external shock load, metal-to-metal between the piston and cylinder liner will take place. Under such conditions of piston slap, excessive oversized clearances will cause.  

Impact forces between the piston and cylinder liner wall increase tremendously due to the excessive clearances accelerating in wear of moving parts. The piston slap and the piston ring clearance are interrelated. The intensity of the piston slap will be the source of high vibration. 

Hence OEM recommendations for the measurement of clearances and change of related parts should be strictly adhered to control the Engine’s vibrations, excessive noise, and catastrophic failures.

Faults in the fuel injection system

The fuel injection system is the Engine’s most crucial and controls the Diesel engine’s performance and reliability. The close examination of injection system conditions and fault diagnosis is the base of the fuel injection system function. A defective fuel injection system is responsible for the exhaust system’s power loss and increased pollutants. A higher fuel injection pressure will fuel consumption and increase emissions. A lower fuel injection pressure will decrease the engine power. A defective fuel injection pressure will cause poor fuel metering and poor fuel combustion.
A defective fuel injector will cause power loss due to improper combustion and high exhaust temperatures. Unbalanced power in each cylinder will result in increased engine vibrations.

Best Books on Engine Vibrations

Investigation of Noise and Vibration Levels

Vibration

The course contents are planned in such a way that the general requirements of the students are fulfilled. This book is written in easy and simple language so that an average student can also grasp the concept by self-study. A large number of figures have been added in each chapter to make the subject matter quite understandable to a great extent. The book contains basic fundamental details of Jatropha and aims to lead a student towards understanding its application. The book is written in a very brief manner which will lead to better understanding in a short span of time. It contains enormous graphs for better visualization of the concepts.

Top Marine Engineering Books

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Blog Conclusion

We hope you enjoyed our blog about Vibration in the marine diesel engine. With the help of this blog piece, we hope that you will be able to understand the content of Vibration in marine diesel engines and how Vibration in marine diesel engines affects the engine.We are so happy that you found it informative and helpful. If you have any questions about Vibration in marine diesel engines, please don’t hesitate to contact us. We would love to hear from you! 

You may like to read our amazing post: Marine Diesel Engine Safety Devices- 22-23 The Best Review

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