DK156044B

DK156044B - Flexibly mounted propeller system

Info

Publication number: DK156044B
Application number: DK380686A
Authority: DK
Inventors: Arnfinn Dyrkorn; Leiv Roar Standal
Original assignee: Brunvoll Motorfab
Priority date: 1983-02-04
Filing date: 1986-08-08
Publication date: 1989-06-19
Also published as: DK380686A; DK156044C; DK380686D0

Description

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5 Den foreliggende opfindelse angår et elastisk lejret propelanlæg af den i krav l's indledning angivne art.The present invention relates to an elastically mounted propeller assembly of the kind set forth in the preamble of claim 1.

Mekanisk betingede kraftimpulser (fra lejer, tandhjul 10 og andre transmissionskomponenter) og hydrodynamisk betingede kraftimpulser (fra uhomogen tilstrømning til propeller, kavitation, m.m.) opstår i propelanlæg og tunnelrør. Disse kraftimpulser forårsager vibrationer af propelaggregat og tunnelrør, og dersom disse 15 komponenter er stift forbundet med skroget, vil vibrationerne brede sig ud over i skrogstrukturen og stråle ud i form af akustisk støj i indretningen.Mechanically conditional power pulses (from bearings, gears 10 and other transmission components) and hydrodynamically conditional power pulses (from inhomogeneous inflow to propeller, cavitation, etc.) occur in propeller systems and tunnel pipes. These force pulses cause vibration of the propeller assembly and tunnel pipe, and if these components are rigidly connected to the hull, the vibrations will propagate into the hull structure and emit in the form of acoustic noise in the device.

Disse strukturbårne vibrationer kan give støj af 20 høj intensitet over et bredt frekvensområde. Typisk støjniveau i tilstødende rum til en konventionel propelinstallation er 80-90dB(A).These structural vibrations can produce noise of 20 high intensity over a wide frequency range. Typical noise level in adjacent rooms for a conventional propeller installation is 80-90dB (A).

Dersom skibet er indrettet sådan, at mennesker må 25 opholde sig i denne zone, vil et sådant støjniveau være uacceptabel miljøbelastning.If the ship is designed to allow humans to stay in this zone, such a noise level would be unacceptable to environmental impact.

Formålet med den foreliggende opfindelse er at fremstille et propelanlæg af den omhandlede art, som 30 er indrettet således, at vibrationer i mindst mulig udstrækning overføres fra propelaggregat/tunnel til skibets skrog, og at støjniveauet i tilstødende rum derved kan holdes på et acceptabelt niveau. Samtidig skal der tages tilstrækkeligt hensyn til enkel instal- 2The object of the present invention is to produce a propeller system of the present kind, which is arranged so that vibrations are transmitted as little as possible from propeller assembly / tunnel to the hull of the ship and so that the noise level in adjacent rooms can be maintained at an acceptable level. At the same time, simple installation must be taken into account 2

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1 lation af anlægget og til skibets sikkerhed.1 lation of the facility and to the safety of the ship.

En betydelig støj- og vibrationsdæmpning kan opnås ved at forbinde propelaggregatet stift med et indre 5 tunnelrør som arrangeres koaksialt inde i et ydre tunnelrør, og fæstes til dette ved hjælp af en elastisk forbindelse, en såkaldt isolator. Dette er en kendt metode til at isolere vibrationer fra maskineri fra omgivelserne. Ved at tilpasse isolatorens elastis-10 ke egenskaber efter kendte regler, vil en betydelig del af svingningsenergien som går ud i propelaggre-gat/indre tunnel forhindres i at brede sig udover i skrogstrukturen. Denne foranstaltning alene er imidlertid ikke tilstrækkelig for at sikre acceptable 15 støjforhold i tilstødende rum. For yderligere støjdæmpning er det tidligere foreslået at aftætne ring spalten mellem det indre, elastisk monterede tunnelrør og det ydre, stift monterede tunnelrør mod indtrængen-r de havvand, således at der i ringspalten indesluttes 20 et støjdæmpende luftvolumen. Med en sådan konstruktion kan opnås en dæmpning som reducerer støjniveauet i tilstødende rum i størrelsesordenen 15dB(A).Significant noise and vibration damping can be obtained by rigidly connecting the propeller assembly to an inner tunnel tube coaxially arranged within an outer tunnel tube and secured thereto by an elastic connection, a so-called insulator. This is a well-known method of isolating vibration from machinery from the surroundings. By adapting the insulating properties of the insulator to known rules, a significant portion of the vibrational energy exiting the propeller assembly / inner tunnel will be prevented from spreading beyond the hull structure. However, this measure alone is not sufficient to ensure acceptable noise conditions in adjacent rooms. For further noise attenuation, it has previously been proposed to seal the gap between the inner, elastically mounted tunnel tube and the outer, rigidly mounted tunnel tube against penetrating seawater, so that a noise attenuating air volume is enclosed in the ring gap. With such a construction, a damping can be achieved which reduces the noise level in adjacent rooms in the order of 15dB (A).

En stor ulempe ved denne konstruktion er imidlertid, 25 at de tætninger, som kræves mellem tunnelrørene til isolation af den indesluttede luftmængde, foruden at de nødvendigvis er store, komplicerede og følgelig kostbare, også ligger meget udsat for skader og punkteringen. .A major disadvantage of this construction, however, is that the seals required between the tunnel pipes for insulation of the enclosed airflow, in addition to being necessarily large, complicated and consequently expensive, are also very prone to damage and puncture. .

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Fra norsk patentskrift nr. 135.462 og DE offentliggørelsesskrift nr. 2 803 336 kendes propelanlæg af ovennævnte art, men hvor ringspalten mellem tunnelrørene er fyldt med lydabsorberende materiale, som 3 1 eliminerer behovet for særskilt aftætning af ringspalten mod havvandet. Ingen af ovennævnte skrifter giver noget konkret eksempel på sådant absorberende materiale, men det vil være klart, at skal det kunne fortræn-5 ge havvandet i ringspalten, må det bestå af et materiale. med lukkede celler eller porer, såsom stift skumplast eller tilsvarende. En blød skumplast, dvs. en skumplast med åbne porer, vil nemlig i væsentlig grad absorbere vandet i stedet for at fortrænge det, 10 og den lyddæmpende effekt vil dermed forsvinde. Det samme gælder brug af andet blødt lydisolerende materiale såsom mineraluldmåtter eller lignende.From Norwegian patent specification 135,462 and DE publication no. 2 803 336 propeller systems of the above-mentioned type are known, but where the ring gap between the tunnel pipes is filled with sound-absorbing material, which eliminates the need for separate sealing of the ring gap against the seawater. None of the above-mentioned writings give any concrete example of such absorbent material, but it will be clear that in order to displace the seawater in the annular gap, it must consist of a material. with closed cells or pores, such as rigid foam or similar. A soft foam plastic, ie. namely, a foam with open pores will substantially absorb the water rather than displace it, and the sound attenuating effect will thereby disappear. The same applies to the use of other soft sound insulating material such as mineral wool mats or the like.

Problemet er imidlertid, at ej heller brug af stift 15 skumplast eller lignende som støjabsorberende, vandfor trængende materiale i ringspalten, vil give den ønskede effekt. Et sådant materiale vil nemlig i kraft af sin stivhed stort set eliminere elasticiteten i forbindelsen mellem tunnelrørene, med den følge 20 at støj og vibrationer fra propeldriften i stor grad overføres til skrogkonstruktionen. I praksis vil løsningerne ifølge de to ovennævnte trykskrifter derfor være af ringe værdi.The problem, however, is that neither the use of rigid foam plastic or the like as noise-absorbing, water-penetrating material in the annular gap will produce the desired effect. Namely, such a material, by virtue of its rigidity, will largely eliminate the elasticity of the connection between the tunnel pipes, with the consequence that noise and vibrations from the propeller operation are largely transmitted to the hull structure. In practice, therefore, the solutions according to the two above-mentioned prints will be of little value.

25 Forannævnte kendte metoder er desuden ' baseret på absorption af lydimpulsernes energiindhold, idet man søger at anvende materiale i spalten, der absorberer den lydenergi, man ikke ønsker overført til skibets skrog.Furthermore, the aforementioned known methods are based on absorption of the energy content of the sound pulses, in that it seeks to use material in the gap which absorbs the sound energy which is not desired to be transferred to the hull of the ship.

Det foran angivne formål opnås ved at udforme anlægget ifølge opfindelsen som nærmere angivet i krav l's kendetegnende del.The foregoing object is achieved by designing the system according to the invention as further specified in the characterizing part of claim 1.

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1 Der dannes derved et blandingsmedium med meget lille ledningsevne over for lydtrykimpulserne. Man afspærrer således skibsskroget fra lydtrykimpulserne.1 A mixture medium with very little conductivity is thus formed against the sound pressure pulses. The ship's hull is thus cut off from the sound pressure pulses.

5 Forsøg udført ved Norges hydrodynamiske laboratorier, Trondhjem, har vist, at en blanding af luft og vand i ringspalten mellem tunnelrørene giver en betydelig støjdæmpning. Allerede med 10% luft og resten vand i ringspalten vil dæmpningen for store dele af støj-10 og vibrationsspektret være af samme størrelsesorden, som hvis ringspalten var fuldstændig fyldt med luft, dvs. aftætnet mod havvandet.5 Tests carried out by Norway's hydrodynamic laboratories, Trondhjem, have shown that a mixture of air and water in the annular gap between the tunnel pipes gives a considerable noise reduction. Already with 10% air and the rest water in the ring gap, the attenuation for large parts of the noise-10 and the vibration spectrum will be of the same order of magnitude as if the ring gap was completely filled with air, ie. sealed against the seawater.

Opfindelsen skal i det følgende beskrives nærmere 15 under henvisning til tegningen, idet fig. 1 viser en skitse, delvis i snit, af et tværskibs monteret propelanlæg konstrueret i henhold til opfindelsen, og 20 fig. 2 viser et snit langs linien II-II på fig. 1.The invention will now be described in more detail with reference to the accompanying drawing, in which 1 is a sectional view of a transverse mounted propeller assembly constructed in accordance with the invention; and FIG. 2 shows a section along line II-II of FIG. First

På tegningen er 1 et konventionelt styrepropelaggre-25 gat, som er anordnet med sin propel 1' væsentligt koaksialt i et i forhold til skibets længdeakse tværløbende, indre tunnelrør 2 til hvilket propelaggregatet 1 er stift fæstnet ved hjælp af radiale arme 3 og rørkappe 4 for aggregatets drivaksel 5. Inderrø-30 ret 2 er på sin side koaksialt elastisk oplejret i et ydre tunnelrør 6 med en vis afstand mellem inder-rør 2 og yderrør 6 sådan, at der dannes en ringformet spalte 7 mellem rørene. Yderrøret 6 er langs sine åbninger fastsvejset til skibets skrogstruktur vedIn the drawing, 1 is a conventional control propeller assembly, which is arranged with its propeller 1 'substantially coaxial in a transverse inner tube 2 relative to the longitudinal axis of the ship, to which the propeller assembly 1 is rigidly secured by radial arms 3 and pipe cover 4 for the drive shaft of the assembly 5. Inner tube 2, in turn, is coaxially resiliently mounted in an outer tunnel tube 6 with a certain distance between inner tube 2 and outer tube 6 such that an annular gap 7 is formed between the tubes. The outer tube 6 is welded along its openings to the hull structure of the ship

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5 1 skibssiden 8. Yderrøret 8 kan også med fordel fast svejses til andre strukturelementer i skroget, så som langskibsbærere, bundstokké og tanktop. Dette øger skrogets stivhed og styrke, og forbedrer yderrø-5 rets egenskaber som fundament for de elastisk lejrede svingemasser.The outer tube 8 may also be advantageously welded to other structural elements in the hull, such as long-ship carriers, bottom sticks and tank top. This increases the stiffness and strength of the hull, and improves the properties of the outer tube as a foundation for the elastically mounted pivot masses.

Den elastiske forbindelse 9 mellem inderrør 2 og yderrør 6 er konstrueret og dimensioneret med sigte 10 på bedst mulig isolation af vibrationerne fra det svingsystem (indre tunnelrør 2 med propelaggregat 1 og forbindelsesorganer 3, 4), som er oplejret i yderrøret 6. Forbindelsen kan bestå af fjedrende elementer af massivt elastomer-materiale ("gummi-iso-15 latorer"), og/eller af gasfyldte puder af elastomermateriale ("pneumatiske isolatorer"). Sidstnævnte type isolatorer er særlig fordelagtig, idet den giver god dæmpning ved passering af resonansfrekvens i start og stopfasen. En sådan overkritisk elastisk 20 oplejring kan uden vanskeligheder udføres af en fagmand på området. På tegningen er denne elastiske forbindelse derfor bare vist rent skematisk som et eksempel i form af dobbelte fjederelementer 9', 9', som virker mod radiale anslag 10, 11 på henholdsvis 25 inderrør 2 og yderrør 6, hensigtsmæssigt fordelt omkring rørenes omkreds.The elastic connection 9 between inner tube 2 and outer tube 6 is designed and dimensioned with sieve 10 on the best possible isolation of the vibrations from the pivot system (inner tunnel tube 2 with propeller assembly 1 and connecting means 3, 4), which is mounted in the outer tube 6. The connection can consist of of resilient elements of solid elastomeric material ("rubber insulators"), and / or of gas-filled pads of elastomeric material ("pneumatic insulators"). The latter type of insulators is particularly advantageous in that it provides good attenuation when passing resonant frequency at the start and stop phases. Such supercritical elastic support can be easily performed by one of ordinary skill in the art. Therefore, in the drawing, this elastic connection is merely shown schematically as an example in the form of double spring elements 9 ', 9' which act against radial stops 10, 11 on 25 inner tubes 2 and outer tubes 6, respectively, suitably distributed around the perimeter of the tubes.

Det indre tunnelrør 2 er omkring sin omkreds i åbningen ved skibssiden udformet med et skråt udadbøjet 30 kantparti 13, som sikrer lav turbulens i vandstrømmen gennem tunnelen og derved mindre støj. Kantpartiet 13 er afsluttet med god afstand til det ydre tunnelrør 6 for at tillade fri relativ bevægelse for inderrøret 2.The inner tunnel tube 2 is formed around its perimeter in the opening at the ship's side with an oblique outwardly bent edge portion 13 which ensures low turbulence in the flow of water through the tunnel and thereby less noise. The edge portion 13 is terminated at a good distance from the outer tunnel tube 6 to allow free relative movement of the inner tube 2.

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6 1 Ringspalten 7· mellem tunnelrørene 2, 6 er således åben ved skibssiden, således at det frit tillades for havvand at trænge ind i spalten 7. Den eneste tætning som er nødvendig er omkring åbningen 14 i 5 det ydre tunnelrør, hvor propelaggregatets drivaksel 5 er ført igennem« I det viste eksempel besørges dette ved hjælp af en højelastik, i tværsnit U-formet tætningsring 15, som med sine respektive sideflader ligger an mod henholdsvis en flange 16 omkring yderåb-10 ningen 14 og en flange 17 på en rørformet forlængelse 18 af akselkappen 4, som strækker sig gennem åbningen 14 med god afstand til yderrørsflangen 16.6 1 The ring gap 7 · between the tunnel pipes 2, 6 is thus open at the ship's side, so that seawater is freely allowed to penetrate the gap 7. The only seal needed is around the opening 14 in the outer tunnel pipe, where the propeller assembly drive shaft 5 In the example shown, this is provided by means of a high elastic, cross-sectional U-shaped sealing ring 15, which with its respective side faces abut a flange 16 around the outer opening 14 and a flange 17 on a tubular extension, respectively. 18 of the shaft sheath 4 extending through the opening 14 at a good distance from the outer tube flange 16.

Såfremt propellen 1* drives af en elektrisk eller 15 en hydraulisk motor (ikke vist), kan drivmotoren med fordel monteres stift til en med den indre tunnel 2 stift forbundet flange, f.eks. flangen 17 på aksel-kappeforlængelsen 18, modsat tætningsringen 15.If the propeller 1 * is driven by an electric or a hydraulic motor (not shown), the drive motor can advantageously be mounted rigidly to a flange connected to the inner tunnel 2, e.g. the flange 17 of the shaft shaft extension 18, opposite the sealing ring 15.

20 Ifølge opfindelsen introduceres gasbobler 22 i ringspalten 7 ved indpumpning af gas, fortrinsvis luft, gennem dyser 19 i væggen på det ydre tunnelrør. Ved at arrangere dyser i hensigtsmæssigt antal og placering på tunnelrørets underside, og forbinde disse 25 via rørledninger 20 til en luftpumpe 21, vil man kunne etablere et bobletæppe i spalten.In accordance with the invention, gas bubbles 22 are introduced into the annular gap 7 by pumping gas, preferably air, through nozzles 19 into the wall of the outer tunnel tube. By arranging nozzles in the appropriate number and location on the underside of the tunnel tube, and connecting these 25 via pipelines 20 to an air pump 21, a bubble blanket in the slot will be established.

Ved at afpasse volumenandelen af luftbobler 22 i forhold til vandvolumenet i spalten 7, vil man under 30 drift kunne opnå en væsentlig reduktion i overføring af trykimpulser gennem blandingen af vand og luftbobler til det ydre tunnelrør 6. Allerede ved en volumenandel af luftbobler på 10%, vil man over en del af frekvensspektret få dampning omtrent svarende tilBy adjusting the volume ratio of air bubbles 22 to the volume of water in the gap 7, during operation 30 a significant reduction in the transfer of pressure pulses through the mixture of water and air bubbles to the outer tunnel tube 6. can already be achieved at a volume percentage of air bubbles of 10%. , over a portion of the frequency spectrum steam will be approximately equal to

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7 1 det, man ville få ved en luftfyldt spalte 7. Ved at øge volumenandelen af luftbobler ud over 10%, vil man opnå tilsvarende dæmpning over et stigende frekvensområde.7 1 that one would get at an air-filled gap 7. By increasing the volume of air bubbles beyond 10%, corresponding attenuation will be achieved over an increasing frequency range.

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Kontinuerlig tilførsel af luft vil være nødvendig for at kompensere for den luftmængde, som til enhver tid undslipper ved ringspaltens 7 ender.Continuous supply of air will be needed to compensate for the amount of air escaping at the ends of the ring gap 7 at all times.

10 Der er imidlertid tale om små luftmængder, tilført ved et lavt tryk (0,5 - 1 atm. overtryk). Systemet kræver derfor små energimængder i drift.10 However, these are small volumes of air supplied at a low pressure (0.5 - 1 atm. Overpressure). The system therefore requires small amounts of energy in operation.

En yderligere fordel er, at den tilførte luftmængde 15 let kan reguleres, mens propelanlægget er i drift, således at optimal luftmængde kan indstilles ved forskellige drifttilstande for propellen.A further advantage is that the supplied airflow 15 can be easily controlled while the propeller system is in operation, so that optimum airflow can be set at different operating conditions of the propeller.

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Claims

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An elastically mounted propeller system for propulsion and / or steering of a ship, in particular installations of the kind in which a propeller operates in an open tunnel through the hull of the ship, comprising a propeller assembly (1) rigidly arranged in an inner tunnel tube (2), coaxially resiliently disposed in an outer tunnel tube (6) rigidly attached to the hull structure (8) of the ship, with an annular gap (7) between the inner and outer tunnel tubes, characterized by a plurality of gas nozzles (19) which are distributed along the underside of the outer tunnel tube (6) and arranged to deliver a continuous gas flow to the annulus (7), thereby forming a continuous flow of gas bubbles (22) in the annulus.

1 PATENT REQUIREMENT

Propeller system according to claim 1, characterized in that the nozzles (19) are arranged to deliver a quantity of gas which produces a gas bubble volume which occupies at least 10% of the volume of the annular gap (7).

Propeller system according to claim 1 or 2, characterized in that the gas is air. 25 30