7/28/2019 Wartsila SP a Tw Engines A

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7/28/2019 Wartsila SP a Tw Engines A

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[ IN DETAIL MARINE ]

In passenger vessels, comfort is keyCareul technical design is required i dieselengines are to achieve their required lietime.

On cruisers and erries, both structural andairborne noise generated by the engines alsohas to be properly isolated rom the hull.Passengers dont eel comortable when theirsurroundings are noisy and vibrating, saysMikonaho. Vibration-related issues can be omajor nancial signicance to shipowners.

Decisions made by ship designers about aships structure and geometry, its engines andpropulsion system and the materials used toreduce noise and vibration throughout thevessel are o undamental

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importance. Advanced auxiliary systems. It cancomputer sotware is WRTSILS TUNED also be utilized as a retrotused to simulate these method to lower vibrationMASS DAMPERvibrations under diferent levels in engines or otherconditions and identiy CAN CUT VIBRATION mechanical devices thatpossible problems. Te are already in service.BY 30-50%vibrations being generatedby onboard equipmentare also compared with the natural requencieso each ship section and the structure is thenadapted i necessary.

Countermeasures may be requiredMore oten than not, restrictions on theavailable space, modular design requirements,manuacturing imperatives and general cost levelsmean that compromises have to be made. Asa systems vibration characteristics can have amajor infuence on the lietime o the productin which it is installed, specic countermeasuresare sometimes needed, says Mikonaho.

In such a situation, active or passive vibrationcontrol devices can be used to lower vibrationlevels. Using a comparatively lightweightcomponent, the system is either tuned to shitthe problem requency o the main vibration

Figure 1

Vibrations of the engine are controlled in wide speed range in all directions.Measured transversal vibration levels on top point TCC 12 of the turbocharger

are shown in graph as an example.

68 Twentyfour7. 1.10

mode away, or to add damping that targets aresonance which is dicult or too expensiveto damp in a direct manner. Our technology is

based on a hydromechanical device that changesthe vibration system. It also converts mechanicalkinetic energy into heat, something like a vehicleshock absorber but on a much larger and moresophisticated scale.

As original equipment and retrofitWrtsils patented tuned mass damper is anauxiliary device that lowers vibration levelsin diesel engines e ciently without requiringeither expensive design modiications or

additional expensive

Te Wrtsil solutioncan be utilized when

traditional methods have already been triedand other methods are either too expensive ortechnically impossible to execute, says Mikonaho.Vibration levels in engine/turbocharger systemscan typically be reduced by 3050%. We nowhave installations on about 20 large diesel enginesand a total o some 200,000 running hourswithout any service or maintenance work on thedampers being required. Te level o technicalreliability is very high.

Next time you take a erry trip or go on acruise, the absence o noise in your surroundingscould well be the result o unseen and unsung

Wrtsil technology, hard at work damping outsources o unwanted vibration in the engine roomand possibly elsewhere, extending equipmentlietimes and reducing service and maintenancecosts.

Figure 2

Twentyour7.

Vibration challengesin diesel enginesLarge diesel engines are very complicated

devices with a design lietime o 30 years or

more. Each engine amily includes many

diferent versions typically with 6, 7, 8, 9, 12, 14,

16 or 20 cylinders. To keep costs down, the main

components use modular design principles

and this can result in vibration becoming a

significant design challenge with some cylinder

configurations. Wrtsils patented tuned

mass damper is an excellent tool or handling

such cases without expensive and dicult

design modifications, says Hannu Tienhaara,

General Manager, Calculation and Simulation at

Wrtsil in Finland.

Collapse of the originalTacoma Narrows BridgeOpened to trac on 1 July 1940, the original

Tacoma Narrows Bridge in Washington State

was the third-longest suspension bridge in the

United States at that time. Just our months

later, on 7 November, a relatively mild but

steady wind excited the transverse vibration

mode in the bridge and it collapsed.

The dramatic, rhythmic twisting motionthat resulted in the collapse is sometimes

described in physics textbooks as a classic

example o ailure resulting rom mechanical

resonance. In act, the catastrophic vibrations

that destroyed the bridge were actually due

to a more complicated phenomenon known

as aeroelastic flutter, oscillation caused

by interactions between the bridge and the

stream o air passing around its structure.

Vibrations of the engine are controlled in wide frequency range.Measured vibration levels of the turbocherger are shown as an example in directions

T = transversal, V = vertical and L = longitudinal.

TCC12_T_d

TCC12_V_d

TCC12_L_d

TCC12_L

TCC12_T

TCC12_V