DOUBLE NOZZLE

Description

[0001] The invention relates to the propulsion of water-borne vessels employing a double nozzle according to the preamble of the claim 1.

[0002] Such a double nozzle is known by GB-A-1,324,356 in which it is described that the propulsion of ships can be improved by fitting a first ring surrounding the propeller along with a second ring coaxial with the first one such that a slot is formed between the two rings which together form a single foil shape. So in any axial section the inner surfaces of the two rings are lying approximately on a common smooth curve and the slot extends inwardly and rearwardly and is shaped such that, in use, the lift produced by the foil is larger than without the slot.

[0003] The object of the invention is to further improve the working of said double nozzle and according to the invention this is obtained by applying the features according to the characterizing portion of the main claim.

[0004] By applying the indicated features the inner surfaces of the two rings are no longer lying on a common smooth curve but a jump is formed between said surfaces. From tests it has appeared that by applying said jump an improvement of the propulsive efficiency is obtained.

[0005] The invention will now be illustrated by way of example with reference to the accompanying drawings, wherein:

Figure 1 shows a longitudinal section of a double nozzle according to the invention; and

Figure 2 shows a similar section in more detail.

[0006] Figure 1 shows the double nozzle, consisting of a main nozzle 1 and a flap nozzle 2, which are connected to a hull 3 of a ship by appropriate means (not shown). Inside the main nozzle operates a propeller, having blades 4 mounted on a hub 5, driven by a shaft (not shown) in a known manner. Seen in the axial direction, the main nozzle has a circular shape. The thickness of the profile of main nozzle 1 is reduced towards its rear end and its thinner part overlaps in part the front part of flap nozzle 2, the opening 6 between the two nozzle profiles extending rearwardly and inwardly.

[0007] Further detail of the latter is shown in Figure 2, wherein main nozzle 1 and flap nozzle 2 are shown (without applied connecting parts) and the opening 6 between the two nozzle profiles. Said opening is formed by the thin part 1a of main nozzle 1 and front part 2a of flap nozzle 2.

[0008] The double nozzle according to the invention can be applied in various combinations with the propeller. The most usual one is to locate the propeller inside main nozzle 1, but in special cases the propeller may be located aft of main nozzle 1.

[0009] It will be obvious that the propeller can be fixed pitch or of controllable pitch type. In the case of a propeller with fixed pitch, the double nozzle may be attached to the blade tips so that both rings will rotate with the propeller.

Claims

1. A double nozzle, consisting of a main nozzle (1) and a flap nozzle (2), coaxially located and operating in conjunction with the main nozzle, a propeller having blades (4) on a hub (5) operating in one of the nozzles, an opening (6) being formed between the two nozzles by the rearward thin part (1a) of the main nozzle (1) and the front part (2a) of the flap nozle (2), said opening (6) extending rearwardly and inwardly, characterized in that the thickness of the profile of the main nozzle (1) is reduced towards its rear end such that the inner and outer wall surfaces of this thinner part (1a) are substantially parallel, said thinner part overlapping the front part (2a) of the flap nozzle (2).

2. A double nozzle according to claim 1, characterized in that said thinner part (1a) of the main nozzle (1) is substantially cylindrical.

3. A double nozzle according to claim 1 or 2, characterized in that said main nozzle (1) and said flap nozzle (2) are connected by extended parts of the nozzle construction.

4. A double nozzle according to one of the preceding claims, characterized in that the connection consists of radial stiffening plates.

5. A double nozzle according to one of the preceding claims, characterized in that it is connected to the fixed pitch propeller blade tips.

Ansprüche

1. Doppeldüse, bestehend aus einer Hauptdüse (1) und einer Ansatzdüse (2) die koaxial zu der Hauptdüse angeordnet ist und in Verbindung mit dieser wirkt, einem Propeller, welcher Blätter (4) auf einer Nabe (5) hat und in einer der Düsen betrieben wird, einer Öffnung (6), welche zwischen den beiden Düsen durch den hinteren dünnen Abschnitt (1a) in der Hauptdüse (1) und den vorderen Abschnitt (2a) der Ansatzdüse (2) gebildet wird, wobei sich die Öffnung (6) nach hinten und innen erstreckt, dadurch gekennzeichnet, daß die Profildicke der Hauptdüse (1) in Richtung auf ihr hinteres Ende verringert ist, so daß die inneren und äußeren Wandflächen dieses dünneren Abschnittes (1a) im wesentlichen parallel verlaufen, wobei der dünnere Abschnitt den vorderen Teil (2a) der Ansatzdüse (2) überlappt.

2. Doppeldüse nach Anspruch 1, dadurch gekennnzeichnet, daß der dünnere Abschnitt (1 a) der Hauptdüse (1) im wesentlichen zylindrisch ist.

3. Doppeldüse nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Hauptdüse (1) und die Ansatzdüse (2) durch Verlängerungsteilen des Düsenaufbaues miteinander verbunden sind.

4. Doppeldüse nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß die Verbindung aus radialen Versteifungsplatten besteht.

5. Doppeldüse nach einem der vorstehenden Ansprüche, dadurch gekennzeichnet, daß sie mit den in festem Abstand vorgesehenen Spitzen der Propellerblätter verbunden ist.

Revendications

1. Double ajutage comprenant un ajutage principal (1) et un ajutage auxiliaire (2), placé coaxialement et fonctionnant concurremment avec l'ajutage principal, une hélice comportant des pales (4) montées sur un moyeu (5) fonctionnant dans l'un des ajutages, une ouverture (6) étant formée entre les deux ajutages par la partie arrière mince (1a) de l'ajutage principal (1) et par la partie avant (2a) de l'ajutage auxiliaire (2), ladite ouverture (6) s'étendant vers l'arrière et vers l'intérieur, caractérisé en ce que l'épaisseur du profil de l'ajutage principal (1) est réduite vers son extrémité arrière de façon que les surfaces des parois intérieure et extérieure de cette partie plus mince (1a) soient sensiblement parallèles, ladite partie plus mince chevauchant la partie avant (2a) de l'ajutage auxiliaire (2).

2. Double ajutage selon la revendication 1, caractérisé en ce que la partie plus mince (1a) de l'ajutage principal (1) est sensiblement cylindrique.

3. Double ajutage selon la revendication 1 ou 2, caractérisé en ce que ledit ajutage principal (1) et ledit ajutage auxiliaire (2) sont reliés par des parties prolongées de la structure des ajutages.

4. Double ajutage selon l'une quelconque des revendications précédentes, caractérisé en ce que la liaison est formée de plaques radiales servant de raidisseurs.

5. Double ajutage selon l'une quelconque des revendications précédentes, caractérisé en ce qu'il est relié aux extrémités des pales de l'hélice à pas fixe.

Drawing