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.
What is Vibration in marine diesel engine?
Vibration is motion or mechanical oscillation induceed by forces on a machine.
Types of Vibration
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
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
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
Is the highest extent of vibration measured 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.
- Displacement;- Displacement means the maximum movement of an object from its stable position to exceed position. The unit of displacement measurement is mils.
- 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)
- Acceleration;- Acceleration indicates the speed of change of velocity of a measured point.
Frequency is the reiteration of vibration. The measurement unit of frequency is HZ.
Damping reduces the degree of oscillation in a substance or of an element mechanical or electrical device.
Formula of Damping
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
. Displacement measurement;- is applicable for measuring frequency below 30 Hz and below.
Velocity measurement;- Is suitable for measuring the frequency between 10 -300 HZ.
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)
Vibration in marine diesel engine
- Drive end ,
- Engine centre,
- Non-drive end of crankshaft.
Take the measurement at the working temperature ofthe engine..
Crankshaft will be in longitudinal direction for the measurement of vibration at engine.
Turbocharger will be in longitudinal direction during measurement of vibration at turbocharger.
Torsional Vibration Damper (spring and oil dashpot type viscous Damper)
Causes of Vibration
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
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.
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. 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
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 short span of time. It contains enormous graphs for better visualisation of the concepts.
Top Marine Engineering Books
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