KR101444293B1 - Duct for propulsion apparatus - Google Patents

Abstract

A duct for a propulsion device is disclosed. According to the duct for the propulsion device according to the embodiment of the present invention, in the duct having the airfoil section formed around the propeller, the cross-sectional shape of the duct includes a nose which is a front vertex of the airfoil section; A tail that is a rear vertex of the airfoil section; A straight line connecting the nose and the tail; And an outer surface of a duct having a front portion convexly formed above the front end of the choke line and a rear portion formed concavely below the rear end of the choke line.

Description

[0001] DUCT FOR PROPULSION APPARATUS [0002]

The present invention relates to a duct for a propulsion device, and more particularly, to a duct for a propulsion device having a duct section optimized in accordance with a flow characteristic according to a general operating condition, a position control, and a towing condition,

In recent years, interest in maneuvering performance and propulsion efficiency of ships has increased, and interest in main propulsion devices and auxiliary propulsion devices attached to ships has been increasing.

For example, a vessel such as a drill ship has been used with azimuth thrusters that generate thrust when navigating at high speed or low speed, or to precise position control or towing other vessels .

The Ajimus thrusters have an open propeller (eg propeller) which does not have a duct depending on the application, and a duct type propeller with ducts of an airfoil section around the propeller.

These azimuth thrusters are provided with horizontally rotatable gears located inside the hull and capable of producing thrust forces for all azimuths, ie all directions.

In order to drill drill ship, dynamic positioning (DP) is indispensably required against environmental loads such as wave-drift force, wind external force, and algae external force .

In addition, since the drill ship uses the azimuth thrusters as an auxiliary propulsion device for the navigation to the drilling site, the general operating conditions of the azimuth thrusters have become very important, and in particular, Depending on the conditions, it can also be very important to generate large manpower.

Patent documents relating to the background of the invention disclose duct-attached thrusters and ships equipped with the same.

In the patent document, the cross-sectional shape of the duct is provided on the outer periphery of the front end portion to bulge outwardly from the standard airfoil into an arcuate cross-section so as to suppress the pressure change on the outer surface of the front end portion of the duct at high speed voyage. And has an opening angle at which the leading edge direction is widened so as to exert an exemplary attractive force.

However, since the shape of the bulge portion itself is bulged outwardly from the leading edge of the duct to a smooth curve, and is formed so as to extend from the maximum bulged portion to the outer surface of the duct with a smooth curve and to extend toward the trailing edge of the duct, Only wave-drift force, external force due to wind, external force due to algae, etc., due to characteristics of the shape of the end, (DP) performance against the environmental load of the vehicle.

In addition, the patent literature refers only to the outwardly bulging shape and the opening angle in which the leading edge direction is widened, and it is a critical design that satisfies all three conditions such as general operating condition, position control and towing condition The argument value is absent.

For example, in the patent literature, there is no description about the distance from the parallel portion of the duct inner surface parallel to the duct axis (the X axis or the rotation axis of the propeller) to the nose and the tail, (YZ plane: propeller rotation plane), the critical design factor for determining the numerical range of the front region and the rear region of the parallel portion is not known, It can not be known how the overall thrust, the propeller torque and the effect of the entire thruster are exclusively influenced, and the contents of these patent literatures alone can attain high positioning efficiency and high efficiency at the same time, It is not possible to develop a propulsion device that can.

For example, the technology of the patent document shows an effect only in the region where the forward ratio is 0.5 or more, and the efficiency is reduced in the region of 0.5 or less, so that the optimized performance is achieved over all the duct operating conditions such as the general operating condition, It has the disadvantage that it can not be.

Japanese Patent Application Laid-Open No. 10-2012-0098941

Embodiments of the present invention can be used to optimize the distance between the nose or tail from the parallel portion of the inner side of the duct and provide a cross sectional shape defined by the front and rear regions of the optimized propeller reference parallel portion, The present invention provides a duct for a propulsion device that can satisfy both the operational condition, the position control, and the towing condition, thereby improving the operational performance, the position control performance, and the towing performance of the ship.

According to an aspect of the present invention, there is provided a duct in which an airfoil section is formed around a propeller, wherein a cross-sectional shape of the duct includes a nose which is a front vertex of the airfoil section; A tail that is a rear vertex of the airfoil section; A straight line connecting the nose and the tail; And a duct for a propulsion device including a front portion convexly formed above the front end of the chord line and an outer surface of the duct having a rear portion recessed below the rear end of the chord line.

The cross-sectional shape of the duct may include a parallel portion parallel to the rotational axis of the propeller; A duct inner surface front portion curved from a starting point of the parallel portion to the nose within a range corresponding to a first distance in the Y axis direction from the parallel portion to the nose; And an inner surface of a duct made up of a duct inner surface rear portion that is curved from an end point of the parallel portion to a tail within a range that is smaller than the first distance but corresponds to a second distance in the Y axis direction from the parallel portion to the tail can do.

The parallel portion may include a front region of the parallel portion having a range of -4.0% to 14.0% of the total length from the propeller surface position, which is a circular surface drawn when the propeller rotates; And a rear region of the parallel portion having a range of -30.0% to -10.0% with respect to the total length from the propeller surface position.

Also, the cross-sectional shape of the duct may include a first distance ranging from 18.0% to 30.0% of the total length from the parallel portion to the nose; And the second distance ranging from 4.0% to 10.0% of the total length from the parallel portion to the tail.

Further, the duct may have a propeller efficiency that can be obtained by the following equation (1).

The duct for the propulsion device according to the embodiment of the present invention has the effect of improving the performance by improving the flow around the duct.

More specifically, embodiments of the present invention can satisfy both general operating conditions, position control and towing conditions by optimizing the first and second distances from the parallel portion of the duct to the nose or tail, The navigation performance, the position control performance, and the towing performance can be improved.

Further, since the embodiment of the present invention has the parallel portion defined by the front region and the rear region of the parallel portion on the basis of the position (propeller position) of the propeller plane (YZ plane), the thrust at the bollard condition is improved , It is possible to maximize the performance of thrust when starting from a stop state such as an ice jam or the position adjustment performance in a stopped state or the towing performance for towing other vessels trapped in the ice, .

1 is an exemplary view showing a duct for a propulsion device according to an embodiment of the present invention.
FIG. 2 is a view showing a distribution of a wire according to the result of a two-dimensional CFD analysis of the duct shown in FIG. 1; FIG.
FIG. 3 is a graph showing the tendency of the propeller efficiency to vary according to the range of the front region and the rear region of the parallel portion with respect to the electric field with reference to the position of the propeller surface in the duct shown in FIG.
Fig. 4 shows a variation tendency of the propeller efficiency according to the range of the total length to the first distance between the parallel portion and the nose in the duct shown in Fig. 1 and the range of the total length to the second distance between the parallel portion and the tail Graph.
5 is a graph showing a Bollard performance curve (Power-thrust) between the duct shown in FIG. 1 and a comparative example.
FIG. 6 is a graph showing a correlation curve between the duct shown in FIG. 1 and the line speed and required horsepower during the comparative example.
7 is a graph showing the propulsive performance characteristic curves obtained by the water tank test to compare the performance of the duct shown in FIG. 1 and the performance of the comparative example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

Further, the comparative example of the embodiment of the present invention is a standard airfoil, which is excellent in air ducting in a duct of the same kind as the duct type azimuth thrust, and thus has a marine 19A airfoil (hereinafter, ).

FIG. 1 is an exemplary view showing a duct for a propulsion device according to an embodiment of the present invention, and FIG. 2 is a diagram showing a distribution of a duct according to a CFD result of the duct shown in FIG.

1, the present embodiment includes a hub 10 that receives power from a gear case on the side of a hull and a rotating shaft, a propeller 20 comprising a plurality of blades arranged along the circumferential surface of the hub 10, , And a ring-shaped duct (100) around the propeller (20).

The cross-sectional shape of the duct 100 may have the same cross-sectional shape along the entire circumference of the duct 100 with respect to the rotation axis (X axis) of the propeller 20.

For example, the cross-sectional shape of the duct 100 may be determined by considering the operating characteristics of a ship such as a drill ship or an offshore structure, the position control characteristics of the ship, and the towing characteristics of other vessels trapped in ice, (DO) and inner surface (DI) of the duct (100) with optimized design parameters to improve the design of the duct (100).

The cross-sectional shape of the duct 100 is an airfoil cross section in which a lift is generated according to Bernoulli's theorem. The cross-sectional shape of the duct 100 is a nose 104, which is the front vertex of the airfoil section of the duct 100. A tail 108 that is the rear vertex of the airfoil section; And a straight line 105 connecting the nose 104 and the tail 108.

The cross-sectional shape of the duct 100 includes a front portion 113 convexly formed above the front end of the chord line 105; And an outer surface DO of the duct 100 having a rear portion 112 recessed below the rear end of the chord line 105.

The front portion 113 of the outer surface DO of the duct 100 may refer to a curved surface from the point where the chord line 105 meets the outer surface DO of the duct 100 to the nose 104.

The rear portion 112 of the outer surface DO of the duct 100 may refer to a curved surface from the point where the chord line 105 meets the outer surface DO of the duct 100 to the tail 108. [

The front portion 113 and the rear portion 112 can be smoothly transited and connected to each other before and after the point at which the chord line 105 meets the outer surface DO of the duct 100.

The front portion 113 of the outer surface DO of the duct 100 is formed to be convex above the front end of the chord line 105. [

Referring to FIG. 2, in the bollard condition, a flow of the front outer region indicated by reference symbol F1 is shown flowing in the nose direction of the duct. Therefore, it can be seen that the flow entering the propeller accelerates because the front part of the outer surface of the duct is convexly formed above the chord line. This accelerating effect makes it possible to improve the duct thrust and reduce the propeller torque.

1, the rear portion 112 of the outer surface DO of the duct 100 is recessed below the rear end of the chord line 105. As shown in FIG.

Referring back to FIG. 2, in the bollard condition, the flow of the rear outer region indicated by 'F2' smoothly flows in the tail direction of the duct, and the eddy current is formed in the tail to improve the duct thrust .

1, the cross-sectional shape of the duct 100 may have an angle of attack?, Which is an angle formed by the rotation axis (X axis) of the propeller 20 and the chord line 105. Here, the angle of attack [alpha] of the duct 100 may have any angle selected from 5 [deg.] To 20 [deg.].

The cross-sectional shape of the duct 100 is a parallel portion 111 parallel to the rotation axis (X-axis) of the propeller 20; A curved surface gently protruding from the starting point 109 of the parallel portion 111 to the nose 104 within a range corresponding to the first distance C in the Y axis direction from the parallel portion 111 to the nose 104 A duct inner surface front portion 106; Of the parallel portion 111 from the end point 110 of the parallel portion 111 within a range corresponding to the second distance D in the Y-axis direction from the parallel portion 111 to the tail 108 while being smaller than the first distance C, And the inner surface DO of the duct 100, which is a curved surface of the duct inner surface rear portion 107, which is gently protruded to the outer surface 108 of the duct 100.

The parallel portion 111 is formed in the front region A and the rear region B of the parallel portion 111 with reference to the propeller plane (YZ plane) position 103, which is a circular surface drawn when the propeller 20 rotates. (L), which can maximize the thrust performance, based on the results of three-dimensional computational fluid dynamics (CFD) analysis, which is a crucial duct design factor that takes into consideration both ship's flight characteristics, position control characteristics and towing characteristics. / L, B / L).

FIG. 3 is a graph showing the tendency of the propeller efficiency to vary according to the range of the front region and the rear region of the parallel portion with respect to the electric field with reference to the position of the propeller surface in the duct shown in FIG.

1 and 3, a three-dimensional computational fluid analysis (CFD) is used to determine the position control characteristics and the towing characteristics of the ship on which the propeller 10 is mounted. The duct 100 in the bollard condition (A / L) (graph abscissa) of the front region A of the parallel portion 111 with respect to the total length L (graph abscissa) and the total length (L) of the parallel portion 111 with respect to the total length L (B / L) (a plurality of graphs inside the graph) of the front region B of the parallel portion 111 are shown.

Here, the efficiency (η ₀ , Merit coefficient) of the propeller is calculated by using the following equation (1), considering performance as an important design condition, such as duct type propeller and Ajimus type propeller, .

As a comparative example, in the patent literature, the solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid solenoid , Propeller diameter, propeller speed, and density of fluid (eg fresh water) as variables.

In the above Equation 1, η ₀ is the propeller efficiency, T _P is the propeller thrust, T _D is the duct thrust, Q is the propeller torque, D _P is the propeller diameter, n is the propeller rotation speed , and ρ is the density of the fluid (eg fresh water).

1 and 3, the cross-sectional shape of the duct 100 of the present embodiment is a parallel portion (A / L) having a range from -4.0% to 14.0% (A / L) from the propeller surface position 103 to the total length L And a rear region B of the parallel portion 111 having a range of -30.0% to -10.0% (B / L) with respect to the total length L from the propeller surface position 103 can do.

Particularly, efficiency can be improved if the parallel portion 111 adjacent to the propeller 20 in the duct 100 maintains a certain length. Therefore, when the A / L value which is the front region A of the parallel portion 111 with respect to the total length L is less than -4.0% or the B / L value which is the rear region B of the parallel portion 111 with respect to the total length L When the value exceeds -10.0%, the length of the parallel portion 111 is narrow and the efficiency improvement effect may be insignificant.

1, a first distance C between the parallel portion 111 and the nose 104 and a second distance D between the parallel portion 111 and the tail 108 are equal to the distance (C / L, D), which can maximize the thrust performance based on the results of three-dimensional computational fluid analysis (CFD), as an important duct design factor that takes into consideration not only characteristics but also position control characteristics and towing characteristics. / L).

Fig. 4 shows a variation tendency of the propeller efficiency according to the range of the total length to the first distance between the parallel portion and the nose in the duct shown in Fig. 1 and the range of the total length to the second distance between the parallel portion and the tail Graph.

The graph's vertical axis in FIG. 4 represents the propeller efficiency (eta 0, Merit coefficient) in the bollard condition (graph vertical axis). In addition, the abscissa of the graph in Fig. 4 represents the% range (C / L) from the total length (L) to the first distance (C). In the graph of FIG. 4, the% range (D / L) relative to the total length (L) with respect to the second distance D is shown.

1 and 4, the cross-sectional shape of the duct 100 of the present embodiment is such that the sectional shape of the duct 100 from the parallel portion 111 to the nose 104 is in the range of 18.0% to 30.0% (C / L) 1 distance C and a second distance D in the range of 4.0% to 10.0% (D / L) from the parallel portion 111 to the tail 108 relative to the total length L.

5 is a graph showing a Bollard performance curve (Power-thrust) between the duct shown in FIG. 1 and a comparative example.

In order to derive the results of FIG. 5, the airfoil section of the duct described above was used, and for comparison of Bollard performance, a marine 19A airfoil was used as a comparative example. In addition, the Bollard performance curves (Power-thrust) for each airfoil section according to the present embodiment and the comparative example can be obtained through a model test (water tank test).

As a result of examining the Bollard performance curve, it can be seen that the airflow cross section of the duct according to the present embodiment is improved to about 6.0% as compared with the comparative example, and the thrust at the bollard condition is improved.

FIG. 6 is a graph showing a correlation curve between the duct shown in FIG. 1 and the line speed and required horsepower during the comparative example.

As can be seen from the correlation curve between the line speed and the required horsepower between the comparative example of FIG. 6 and the cross-section of the airfoil of this embodiment, the performance improvement is about 4.6% even under the normal operating conditions.

For example, it can be seen that the embodiment can achieve a higher speed compared to the comparative example, or a performance improvement is required by requiring a smaller required horsepower than the comparative example of the same speed, compared to the same required horsepower (DHP).

7 is a graph showing the propulsive performance characteristic curves obtained by the water tank test to compare the performance of the duct shown in FIG. 1 and the performance of the comparative example.

In the graph of Fig. 7, the graph abscissa shows the change tendency with respect to the propeller advance ratio J, and the graph vertical axis shows the thrust Kt, the torque 10Kq, and the efficiency? _O.

Referring to FIG. 7, in the duct of this embodiment, the torque (10Kq) was reduced in all the forward coefficient J regions as compared with the 19A airfoil of the comparative example.

(Kq: about 7% decrease, Kt: about 1% decrease) is calculated by calculating the same engine horsepower using 10Kq and Kt results in the bollard region (J = 0) (Η _O ) of 4.0% to 7.0% in the region of the forward coefficient (J) of 0.4 or more. In other words, the flow rate to the propeller is increased due to the increase of the suction force of the duct, which shows that the propeller torque (10Kq) is reduced and the efficiency is improved in all the forward coefficient (J) range.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, You will understand. For example, a person skilled in the art can change the material, size and the like of each constituent element depending on the application field or can combine or substitute the embodiments in a form not clearly disclosed in the embodiments of the present invention, Of the range. Therefore, it should be understood that the above-described embodiments are to be considered in all respects as illustrative and not restrictive, and that such modified embodiments are included in the technical idea described in the claims of the present invention.

10: hub 20: propeller
100: duct 104: nose
105: Chord line 106: Duct inner front part
107: duct inner surface rear portion 108: tail
111: parallel portion 112: rear portion
113: front portion

Claims (5)

In a duct in which an airfoil section is formed around a propeller,
The cross-sectional shape of the duct,
A nose which is a front vertex of the airfoil section;
A tail that is a rear vertex of the airfoil section;
A straight line connecting the nose and the tail; And
And an outer surface of a duct having a front portion convexly formed above the front end of the choke line and a rear portion recessed below the rear end of the choke line,
A parallel portion parallel to the rotation axis of the propeller;
A duct inner surface front portion curved from a starting point of the parallel portion to the nose within a range corresponding to a first distance in the Y axis direction from the parallel portion to the nose; And
Further comprising an inner surface of the duct made up of a duct inner surface rear portion that is curved from the end point of the parallel portion to the tail within a range that is smaller than the first distance but corresponds to a second distance in the Y axis direction from the parallel portion to the tail Duct for propulsion system. delete The method according to claim 1,
The parallel portion includes:
A front region of the parallel portion having a range of -4.0% to 14.0% with respect to the total length from a propeller surface position which is a circular surface drawn when the propeller rotates; And
And a rear region of the parallel portion having a range of -30.0% to -10.0% from the propeller surface position with respect to the total length of the duct. The method according to claim 1,
The cross-sectional shape of the duct,
The first distance ranging from 18.0% to 30.0% of the total length from the parallel portion to the nose; And
And the second distance in the range from 4.0% to 10.0% of the total length from the parallel portion to the tail. The method according to claim 1,
In the duct,
Wherein the duct has a propeller efficiency obtained by the following equation.
(Equation)

Wherein an equation, η ₀ is the propeller efficiency (Merit coefficient), T _P is a propeller thrust, and T _D is the duct thrust, and Q is the propeller torque, the D _P is the propeller diameter, n can rotate the propeller, ρ is The density of the fluid.

Images