JPH085431B2 - Marine propulsion device - Google Patents

Description

The present invention relates to a marine propulsion device.

(Prior Art) As a marine propulsion device, a tandem propeller (Japanese Patent Laid-Open No. 57-205297) in which at least two sets of propellers are attached to the propulsion shaft with the front and rear sets separated from each other, and the ratio of front and rear propeller diameters is changed. A tandem propeller (Shokai 56-30195
JP-A-57-139500) and a propeller boss cap with fin (JP-A-63-154494).

(Problems to be Solved by the Invention) In the above-mentioned tandem propeller, large and small propeller blades are mounted on the front and rear of the propeller shaft, and in this case, the direction of the induced velocity induced by the front propeller is rearward of the propeller shaft. Since the flow is accelerated to the same direction, and because it is in the same direction as the rotating direction, the efficiency of the rear propeller operating in the wake of this front propeller is unavoidable.

This will be described with reference to FIGS. 17 to 21.
The figure shows a view of one blade of a propeller from the rudder side. Let R be the propeller radius and r the arbitrary radial position.

FIG. 18 shows a view in which the propeller blade is cut by a cylinder having a radius r and the cut end is extended in a plane. The propeller blade has a pitch like a screw, and has a pitch angle θ with respect to the rotating direction (a pitch surface is defined by a so-called Nose-Tail Line connecting the leading edge and the trailing edge of the blade). A camber is attached to the front of the propeller on the cross section of the wing (see Fig. 19).

When the propeller rotates and moves forward, water enters from the direction of β _i with respect to the rotation direction as shown in Fig. 18 (Note that in Fig. 18, the propeller induction speed is the rotation and forward movement of the propeller. The flow of water induced by motion, sucked into the propeller, and sways in the direction of propeller rotation). The lift L acting on the blade increases as the difference between θ and β _i , that is, the angle of attack θ−β _i increases, and the camber of the blade cross section increases.

Further, the lift force L acts at right angles to the inflow direction of water, and the forward direction component thereof becomes the thrust force T and the rotation direction component thereof becomes the rotation resistance force F.

The pitch and camber are determined so that the rotational torque transmitted from the engine and the rotational resistance torque Q = F × r are balanced.

The propeller efficiency η _o is expressed by the following equation (2).

η _o = υ _a / 2πn) ・ (T / Q) ∽T / Q∽T / F = cotβ
_i (2) Formula υ _a is a propeller forward speed, n is a propeller rotation speed, and Q is a rotation torque.

From this equation (2), it is understood that the propeller efficiency is better as the ratio T / Q of the thrust T and the rotational torque Q or the ratio T / F of the thrust T and the rotational resistance force F is larger, and as the β _i is smaller.

Next, as shown in FIGS. 20 and 21, consider a tandem propeller in which propeller blades are mounted in front of and behind the propeller shaft. In the case of the tandem propeller, since the front propeller blade is placed in front of the rear propeller blade, the induced velocity by the rear propeller blade is added, and β _i becomes a little larger and becomes β _i ′, as shown in FIG. . As a result, as can be seen from the equation (2), η _o becomes small and the propeller efficiency becomes poor.

Similarly, for the rear propeller blades, the guide velocity by the front propeller blades is added because they are placed in the wake of the front propeller blades (the propeller guide velocity is accelerated and becomes faster toward the rear). As shown in FIG. 21, β _i is greatly increased by the induction velocity by itself, and β _i ″
Becomes

That is, in the conventional marine propulsion device in which large and small propeller blades are mounted on the front and rear of the propeller shaft, the guide velocities of the front and rear propeller blades adversely affect each other, and it is difficult to improve the propeller efficiency.

The present invention has been devised to solve the above-mentioned problems of the prior art, and a first object thereof is to mount a turbine blade behind a propeller blade to improve the propeller efficiency of the entire apparatus.

That is, the basic difference between the propeller blade and the turbine blade in the present invention is that the former gives energy to the fluid to generate a propulsive force by its reaction force, whereas the latter obtains rotational torque from the energy of the fluid. Therefore, the first object was achieved by paying attention to the fundamental difference that the induction velocities also occur in completely opposite directions.

(Means for Solving the Problem) The present invention takes the following technical means in order to achieve the above-described first object.

That is, in the present invention according to claim 1, the propeller shaft 1
In a marine propulsion device equipped with a propeller blade 2, a turbine blade 3 having a diameter smaller than that of the propeller blade 2 is mounted behind the propeller blade 2 with the same axial center as the propeller blade 2. 3 is characterized in that the flow velocity of the water discharged backward from the propeller blade 2 is suppressed.

Further, in the present invention according to claim 2, the propeller blades 2 are mounted with the same axial center in the front and rear with a distance in the axial direction.
And the axial distance l of the turbine blade 3 is 6% or more, the number of blades of the turbine blade 3 is an integral multiple of the number of blades of the propeller blade 2, and the diameter of the turbine blade 3 is the diameter of the propeller blade 2. It is characterized by being 33% to 60% of. However, the distance 1 is a value (%) obtained by dividing the distance between the center lines of both blades 2 and 3 by the propeller diameter.

Further, in the present invention according to claim 3, the pitch angle θ _P of the propeller blade 2 and the pitch angle θ _T of the turbine blade 3 are 0.3 ≦ r / R.
At the position of ≦ 0.6, θ _T ≦ θ _P + 20 °. However, R is a propeller blade radius, and r is an arbitrary radial position.

(Operation) The fundamental difference between a propeller blade and a turbine blade is that the former gives energy to the fluid to generate propulsive force by its reaction force, while the latter obtains rotational torque from the energy of the fluid. .

Therefore, in the marine propulsion device according to the present invention in which the propeller blades 2 are mounted on the front side of the propeller shaft 1 and the turbine blades 3 having a diameter smaller than that of the propeller blades 2 are mounted on the rear side of the propeller blades 1, as shown in FIG. While the thrust T _P ′ is obtained by applying the rotation torque Q _P ′ corresponding to the rotation resistance F _P ′, in the turbine blade, the thrust is the backward resistance −
Instead of T _T ″, the rotational resistance is the force that reduces it −
F _T ″.

The rotational torque corresponding to -F _T ″ is −Q _T ″. Thrust the T _P in the case of the propeller alone, when the rotational torque represented by Q _P, propeller efficiency of the propeller alone _{(υ a / 2πn) · (} T P /
Whereas the Q _P), a propeller efficiency of marine propulsion device according to the present invention, in the front side of the propeller, (υ _{a /} 2π
n) · (T _P ′ / Q ′ _P ), and the overall propeller efficiency changes as (υ _a / 2πn) · {(T _P ′ −T _T ) / (Q _P ′ −Q _T )} .

The induced velocity of the turbine blade pushes the water expelled rearward from the propeller blade forward and rotates it in the direction opposite to the propeller rotation. Since the flow due to this turbine blade is smaller than the wake behind the propeller, the wake behind the propeller does not flow in the opposite direction, and the flow velocity of the wake behind the propeller is suppressed.

Therefore, in the present invention, for the propeller blade mounted on the front side, β _Pi becomes as small as _{β'Pi due} to the induced velocity of the turbine blade as shown in FIG. As a result, T _P ′ ＞
T _P , Q _P ′ <Q _P , and the efficiency of the front propeller blade is improved compared to the single propeller blade. On the other hand, with respect to the rear turbine blade, since the direction of the generated force is opposite to that of the propeller blade, the larger β _i is, the more advantageous the efficiency is. Overall propeller efficiency by as compared to the beta _Pi propeller vane beta _Ti of the turbine blade is designed turbine blade so as to satisfy the beta _Pi <beta _Ti becomes better. Β _Ti is small on the front side of the propeller blade, but if the turbine blade is placed on the rear side of the propeller blade, the propeller induction speed is accelerated and β _Ti becomes large, which is effective.

When viewed as a whole of the marine propulsion device according to the present invention, the thrust is almost the same as that of the propeller alone. The reason for this is that thrust increases on the front side propeller blades, but it cancels out on the rear side turbine blades because the thrust acts in the opposite direction. On the other hand, since the rotating torque decreases, the propeller efficiency increases.

Further, when the wake of the propeller collides with the surface of the turbine blade, the turbine blade becomes a solid wall, and the effect of blocking the wake of the propeller can be considered. In particular, if the turbine blade is placed in the wake of the propeller while the propeller induction speed is being accelerated, the damming effect is also increased.

(Embodiment) An embodiment and operation of the present invention will be described below with reference to the drawings.

In FIG. 1 and FIG. 2, a propeller blade 2 is attached to a propeller shaft 1 on the front side (traveling side or hull side) and a turbine blade 3 is mounted on the rear side, and the axial length L of both blades 2 and 3 is shown.
(See FIG. 3) is 6% or more, the number of blades of the turbine blades 3 is an integral multiple of the number of blades of the propeller blades 2, and the diameter of the turbine blades 3 is 33 to 33 times the diameter of the propeller blades 2. The marine propulsion device set to 60% is shown, and in FIG.
Indicates propeller boss and 4 indicates a cap.

However, the axial length L is a value (%) obtained by dividing the distance between the center lines of both blades 2 and 3 by the propeller diameter (see FIG. 3).

The propeller blade 2 and the turbine blade 3 have geometrical shapes such that the pitch and the camber are designed as θ + α _o −β _i > 0 (3) in the propeller blade, whereas θ + α _o −β _i <0 ( Designed according to equation 4). Note that α _o is the zero lift angle of the blade cross section (the angle between the inflow direction of water when the lift is zero and the pitch surface), which is positive when the camber is forward, negative when the camber is backward, and zero when the camber is zero. Become.

The fundamental difference between a propeller blade and a turbine blade is that the former (propeller) gives energy to the fluid to generate propulsive force by its reaction force, while the latter (turbine) rotates from the energy of the fluid. It is a device that obtains torque.

The flow fields of the front and rear turbine blade cross sections of the propeller with turbine blades are shown in Figs. 12 and 13. In the propeller blade as shown in Fig. 12, the thrust T _P ′ is obtained by giving the rotating torque corresponding to the rotational resistance force F _P ′, whereas in the turbine blade, the thrust is backward as shown in Fig. 13. Resistance- _{T T} ″
Instead, the rotational resistance becomes a force that reduces it −F _T ″. The thrust is generated by the propeller, and the turbine blade functions as an auxiliary blade that receives energy from the wake of the propeller and reduces the rotational resistance torque. In other words, the turbine blade propeller is a completely different device from the tandem propeller.

The induced velocity of the turbine blade is generated in the direction opposite to that of the propeller induced velocity. Whereas the propeller induced velocity is sucked into the propeller and circulates in the propeller rotational direction, the turbine vane induced velocity pushes the flow forward and rotates in the opposite direction to the propeller rotational direction.

The propeller efficiency of the propulsion device according to the present invention in which a propeller blade is mounted on the front side of the propeller shaft and a turbine blade having a smaller diameter than the propeller blade is mounted on the rear side of the propeller shaft will be described below.

For the front side propeller blade, β _Pi becomes as small as _{β'Pi due} to the induced velocity of the rear side turbine blade. As a result, the efficiency of the propeller blades is improved. On the other hand, for the rear turbine blade, since the direction of the generated force is opposite to that of the propeller blade, the larger β _{i, the} better the efficiency. If it is possible to beta _Ti of the turbine blade as compared to the beta _Pi propeller vane to design the turbine blades so as to satisfy the β _Pi <β _Ti (5) expression efficiency is better. Β _Ti is small on the front side of the propeller blade, but if the turbine blade is placed on the rear side of the propeller blade, the propeller induction speed is accelerated and β _Ti becomes large, which is effective.
Further, when the wake of the propeller collides with the surface of the turbine blade, the turbine blade becomes a solid wall, and the effect of blocking the wake of the propeller can be considered. In particular, if the turbine blade is placed in the wake of the propeller while the propeller induction speed is being accelerated, it is considered that this damming effect is also increased.

Further, from the relationship between the propeller induction speed and the propeller efficiency in the stern wake, the effect of the propulsion device according to the present invention is large in the wake, and the diameter of the turbine blade may be selected within a range where the wake is large. I think that the.

Based on the above consideration, targeting a four-blade propeller for a high-speed ship, the number and diameter of the turbine blades located behind the propeller are changed to improve the efficiency of the propulsion device according to the present invention in the wake. Calculated by theory. Regarding the front and rear positions of the turbine blade, a value 1 obtained by dividing the distance from the propeller center line to the turbine blade center line on the boss surface by the propeller diameter.
It is expressed as (%) and is positive when the turbine blade is placed behind the propeller (see FIG. 3). The turbine blade diameter is expressed as a percentage of the propeller diameter.

The number of turbine blades is 4 and the diameter is the propeller diameter.
Table 1 and Fig. 14 show the calculation results when the turbine blade position was changed to 0%, 13% and 20% assuming 45%. In the table, K _T is the thrust coefficient (= T / ρ n ² D _P ⁴ , T: thrust, ρ: water density, n: propeller speed, D _P : propeller diameter), and K _Q is the torque coefficient (=
Q /; ρ n ² D _P ⁵ , Q = torque), Δη _O is the efficiency improvement amount (%) compared with the efficiency of the propeller alone. From these figures, if the turbine blade is placed behind the propeller from 1 = 1%, the propeller efficiency will be improved, and efficiency will be increased to 1.8% or more considering the cost of turbine blade design and manufacturing. Then, L becomes l> 6% (6) formula.

The turbine blade position is l = 13%, the diameter of the turbine blade is 45% of the propeller diameter, and the number of turbine blades is 4,
Table 2 and Fig. 15 show the results when 8 blades and 12 blades were changed. From these figures, it can be seen that if the number of turbine blades is an integral multiple (1 to 3 times) of the number of propeller blades, the efficiency will increase by 1.8% or more.

The turbine blade position is l = 13%, the number of turbine blades is 4, and the diameters of the turbine blades are 25%, 35%, 45%, 55%,
The results when changing to 65% are shown in Table 3 and FIG. From these figures, increasing the diameter of the turbine blade increases the efficiency improvement amount, but if it increases too much, it decreases conversely, and the efficiency is 1.8% within the range of 33% D _P <turbine blade diameter <60% D _P (7). It turns out that it is possible to increase by more than%.

Next, the correlation between the pitch angle of the front propeller and the pitch angle of the rear turbine blade was investigated. Basically, if the pitch and camber of the rear blades are determined so as to satisfy equation (4), a turbine blade will be obtained, but if equation (4) is rewritten using the symbols in FIG. 13, the following equation is obtained.

θ _T + α _To −β ′ _Ti <0 (4) ′ where α _{To is} the zero lift angle of the rear turbine blade, where α _To is zero if the camber of the rear blade is zero, that is, a flat plate. Therefore, the equation (4) ′ becomes the equation θ _T −β ′ _Ti <0 (8).

Further, if the pitch angle θ _T of the rear blade is made to coincide with the propeller wake direction β _Ti , the induced velocity by the rear blade becomes zero and β ′ _Ti becomes equal to β _Ti . That is, if the pitch angle of the flat blade on the rear side is θ _T <β _Ti (9), the rear blade is a turbine blade.

Empirically, in the range of the expressions (6) and (7), β _Ti and θ _P (the pitch angle of the front propeller blade) are approximately equal.
By substituting this relationship into the equation (9) and considering the zero lift angle α _To due to the camber of the rear blade, the equation (9) becomes θ _T <θ _P −α _To (10).

Furthermore, if the camber is not made extremely large, the zero lift angle due to the camber is considered to be in the range of 0 ° to -20 °, so equation (10) becomes equation (11) below.

When the _{θ T ≦ θ P + 20 °} (11) Equation 4 FIG. Referring to FIG. 11, some embodiments of the mounting of the turbine blade 3 (attachment) means is illustrated.

4 and 5, the ring 3A provided at the base of the turbine blade 3 is interposed between the propeller boss 2A and the propeller cap 4 at the rear of the boss to cover the propeller shaft 1, and the bolts 5, 6, In this case, Fig. 4 shows an embodiment in which propeller boss 2A, ring 3A and cap 4 are fastened together by bolts 5, and Fig. 5 shows propeller boss. 2A shows that the ring 3A is fastened to the ring 3A with bolts 6, and the cap 4 is fastened to the ring 3A with bolts 7. Bolts formed axially in a radial arrangement on the ring 3A as shown in FIGS. 6 to 8. Each bolt using the insertion hole 3C
5,6,7 are concluded.

9 to 11 show the turbine blade 3 with the propeller boss 2A.
In this embodiment, the turbine blade 3 is detachably fixed to the outer peripheral surface of the turbine blade by means of screw fastening means.
It has a flat flange 13A having B, and this flange 13
Overlap A on the outer peripheral surface of Propella Boss 2A and bolt 13C.
Is inserted into each fastening hole 13B, and each bolt 13C is fastened to a female screw formed on the boss.

6 to 8 show the relationship between the ring 3A and the turbine blade 3, and FIG. 6 shows that the dovetail groove 3B is formed in the axial radial position of the ring 3A in the axial direction and the base portion of the turbine blade 3 is formed. A dovetail-shaped projection 3D formed on the base of the turbine blade 3 with its end surface superposed on the outer peripheral surface of the ring 3A is fitted in the dovetail groove 3B in the axial direction. In this embodiment, the projection is formed.
3D axial regulation is propeller boss 2A and propeller cap 4
Made in.

FIG. 7 shows an embodiment in which the turbine blade 3 and the ring 3A are integrally formed by casting or welding. In addition, 9th
Also in the embodiment shown in FIG. 11, the turbine blade 3 and the flange 13A are integrally formed as described above.

FIG. 8 shows an embodiment in which mounting holes 3E are formed in the ring 3A in a radial arrangement, a projection 3D having a threaded portion is inserted into the mounting holes 3E, and a nut 8 is screw-fastened.

In addition, in each of the above-described embodiments, the ring 3A may be a split ring, and the turbine blade 3 may have a mounting angle adjusting means.

The turbine blade 3 and the ring 3A or the flange 13A can be made of the same material as the propeller (for example, copper alloy) or a composite material such as FRP.

(Advantages of the Invention) The present invention is as described above, and since the turbine blade is provided behind the propeller blade, the higher the propeller guide speed, that is, the faster the flow behind the propeller shaft, and the rotation direction. The larger the flow around, the more effective it is, and the propeller efficiency can be improved.

In addition, since the torque decreases, the rotation of the propeller that has become heavier (decreased in rotation) due to ship hull contamination and deterioration of the main engine on the in-service ships can also reduce the rotation. it can.

[Brief description of drawings]

FIG. 1 is a front view showing an embodiment of the present invention, FIG. 2 is a side view of the same, FIG. 3 is an explanatory view showing a front-rear positional relationship between a propeller blade and a turbine blade, and FIGS. 4 and 5 are turbines. FIG. 6 is a front view showing a third embodiment of a turbine blade attached to a ring, and FIG. 6 to FIG. 8 are side views of essential parts showing two embodiments of the present invention in which a blade is interposed between a propeller boss and a propeller cap. Fig. 9, Fig. 9 is a side view of a main part where a turbine blade is attached to a propeller boss via a flange, Fig. 10 is a side view of a turbine blade with a flange, Fig. 11 is a plan view of the same, and Fig. 12 is an embodiment of the present invention. A cross-sectional flow field diagram of the front and rear propeller blades according to an example, FIG. 13 shows a cross-sectional flow field diagram of the rear turbine blade in the same manner, and FIG. 14 is a graph showing the relationship between the propeller efficiency increase amount and the turbine blade position, Fig. 15 shows the amount of increase in propeller efficiency and the number of turbine blades. Fig. 16 is a graph showing the relationship between the propeller efficiency increase amount and the diameter of the turbine blade, Fig. 17 is a front view of one propeller blade, Fig. 18 is a sectional flow field diagram of the propeller blade, and Fig. 19 Shows a camber of a propeller blade cross section, FIG. 20 is a blade cross section flow field diagram of a front side propeller in a tandem propeller which is a conventional example, and FIG. 21 is a blade cross section flow field diagram of the same rear propeller. 1 ... propeller shaft, 2 ... propeller blades, 2A ... propeller boss,
3 ... Turbine blade

Front page continued (72) Inventor Isao Sasada 1486-290 Umezawa, Ishizaka, Hatoyama-cho, Hiki-gun, Saitama Prefecture Inventor Hatsuno Uemori 2-6-1, Nakajima, Takasago-shi, Hyogo Univ. (72) Dai Nishimoto Tsukasa, Takasago, Hyogo 2-6-1, Nakajima (56) References JP 62-12495 (JP, A) JP 53-11490 (JP, A)

Claims (3)

[Claims] 1. A marine propulsion device in which a propeller blade (2) is mounted on a propeller shaft (1), wherein a turbine blade (3) having a smaller diameter than the propeller blade (2) is provided behind the propeller blade (2). ) Is mounted as the same axis as the propeller blade (2), and the turbine blade (3) is shaped so as to suppress the flow velocity of water discharged backward from the propeller blade (2). And a marine propulsion device. 2. A propeller blade (2) and a turbine blade (3) mounted on the front and rear with the same axial center with a distance in the axial direction.
Is 6% or more, the number of blades of the turbine blade (3) is an integral multiple of the number of blades of the propeller blade (2), and the diameter of the turbine blade (3) is The marine propulsion device according to claim 1, characterized in that the diameter is 33 to 60% of the diameter of the blade (2). However, the distance (l) is a value (%) obtained by dividing the distance between the center lines of the blades (2) and (3) by the propeller diameter. Pitch angle theta _T of 3. A pitch angle theta _P and the turbine blades of the propeller blades (2) (3), at the position of 0.3 ≦ r / R ≦ 0.6, that is θ _T ≦ θ _{P +} 20 ° The marine propulsion device according to claim 1, which is characterized in that. However, R is a propeller blade radius, and r is an arbitrary radial position.