JP2003254293A - Jet fan - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a jet fan wherein efficiency is remarkably improved and noise is reduced in conformance to a large air quantity without using a structurally complicating rotor blade reversing mechanism and the like. <P>SOLUTION: Rotor blades 5 of fans 6 have a streamline profile. At air current generation, the rotor blades 5 of the fan 6 that is positioned in a front stage bear a 100% workload rate, and the rotor blades 5 of the fan 6 that is positioned in a back stage bear a 0% workload rate. Support legs of a double shaft motor have a flat plate form and a mounting angle conformed to an outlet angle of an air current from a trailing edge of the tip of the rotor blades 5 of the fan 6 positioned in the front stage. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial-flow type jet fan provided on a ceiling portion of a tunnel and for ventilating the inside of the tunnel. 2. Description of the Related Art Generally, in a tunnel in which a car travels, a driver's visual environment is ensured, harmful substances such as carbon monoxide and sulfur dioxide discharged from the car are diluted, and an evacuation route in the event of a fire is established. Ventilation needs to be performed for the purpose of securing or the like. For this reason, an axial flow type jet fan is provided on the ceiling of the tunnel. FIG. 9 is a perspective view showing an example of a general jet fan. Reference numeral 1 denotes a jet fan. The jet fan 1 is supported in a cylindrical casing 2 attached to a ceiling of a tunnel. A dual-axis motor 4 is provided so as to be concentric with the legs 3, and a fan 6 having a plurality of moving blades 5 is fitted to each axis of the dual-axis motor 4. When the two-axis motor 4 is rotated forward, a forward airflow 7 is generated.
Is reversed, an airflow 8 in the opposite direction is generated. Conventionally, in order to realize the function of bidirectional air blowing with the same specifications by reverse rotation, the airfoil of the moving blade 5 of the fan 6 has a symmetrical shape in which the back and front surfaces are circular and have no warpage. Was used. [0005] However, as described above, if the blades of the rotor blades 5 of the fan 6 are of a symmetrical shape in which the back surface and the front surface are circular and have no warpage, the aerodynamic ,
The noise characteristics were poor, and it was difficult to achieve a significant increase in efficiency and a reduction in noise in response to a large air volume. For this reason, it has been considered to improve the aerodynamic and noise characteristics by making the airfoil of the rotor blade 5 of the fan 6 streamlined. In this case, the function of bidirectional air blowing with the same specifications by reverse rotation is considered. In order to realize this, a blade reversing mechanism is indispensable. However, providing the moving blade reversing mechanism in the jet fan has a disadvantage that the entire structure becomes complicated and leads to an increase in cost. The present invention has been made in view of the above circumstances, and provides a jet fan capable of significantly increasing efficiency and reducing noise corresponding to a large air flow without providing a moving blade reversing mechanism having a complicated structure. What you are trying to do. According to the present invention, there is provided a cylindrical casing mounted on a ceiling of a tunnel, a double-shaft motor disposed concentrically by supporting legs in the casing, and A fan fitted to each shaft of the dual-shaft motor and having a moving blade, wherein the dual-shaft motor rotates forward or reverse to generate a forward or reverse airflow; And the work load of the rotor blade of the fan located at the front stage at the time of airflow generation is set to 100%, and the work load ratio of the rotor blade of the fan located at the rear stage is set to 0%, The present invention relates to a jet fan, wherein the support legs of the double-shaft motor are formed in a flat plate shape, and the mounting angle thereof is made to coincide with the outflow angle of the airflow from the trailing edge of the leading edge of the rotor blade of the fan located at the front stage. You. According to the above means, the following effects can be obtained. The airfoil shape of the moving blade of the fan is made streamlined, and the work load of the moving blade of the fan located at the front stage is set to 100% when the air flow is generated, and the work load of the moving blade of the fan located at the rear stage is reduced. If it is set to 0%, the aerodynamic and noise characteristics are good and the wind is large unlike the conventional case where the back and front shapes of the fan blades are symmetrical with no arc and no warp. Significantly higher efficiency and lower noise can be achieved in response to the quantity increase, and there is no need to provide a rotating blade reversing mechanism to realize the function of bidirectional air blowing with the same specifications by reversing, making the overall structure complicated If the support legs of the two-axis motor are made flat and the mounting angle is made to match the outflow angle of the airflow from the trailing edge of the tip of the rotor blade of the fan located at the front stage. Minimizes drag without twisting the support legs It can be suppressed to become. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of an embodiment of the present invention. In FIG. 1, portions denoted by the same reference numerals as those in FIG. 9 represent the same components. As shown in FIG. 1, the blades 5 of the fan 6 have a streamlined airfoil shape, and the work load of the rotor blades 5 of the fan 6 located at the front stage at the time of airflow generation is set to 100% and the work load ratio at the rear stage is determined. The work load rate of the rotor blades 5 of the fan 6 to be performed is set to 0%.
When the rotation direction is the direction of the arrow (right direction in FIG. 1),
The rotor blades 5 of the fan 6 located at the front stage have a normal blade shape with a round front edge and a sharp rear edge, whereas the rotor blades 5 of the fan 6 located at the rear stage have a sharp front edge and a round rear edge. The shape is opposite to the normal blade shape, and the rotor blade 5 of the fan 6 located at the subsequent stage does not give energy to the airflow. To explain the speed triangle, when energy is given by the fan 6 located at the preceding stage at the time of airflow generation, the relative phase is W1 at the entrance of the moving blade 5 due to the lift of the moving blade 5, but W at the exit of the moving blade 5.
The absolute speed is C1 at the entrance of the moving blade 5, but becomes C2 at the exit of the moving blade 5. In the subsequent fan 6, the relative speed remains at W2 and the absolute speed also remains at C2. still,
In FIG. 1, U is a peripheral speed. The fan 6 located at the preceding stage when the air flow is generated
FIG. 2 shows the inflow direction and outflow direction of the airflow with respect to one blade 5. That is, when the fan 6 is rotating at the rotation speed N in the flow of the velocity V in the axial direction, the cross section of the tip, the center, and the root of the rotor blade 5 has an axial flow component V _i (V ₁ , V ₂ , V ₃ ) and the flow in the combined vector direction of the flow components T _i (T ₁ , T ₂ , T ₃ ) in the direction opposite to the rotation flow in from the leading edge of the bucket 5. In FIG. 2,
X ₁ -X ₂ is a reference line connecting the leading edge and the trailing edge of the section at the tip of the bucket 5, Y ₁ -Y ₂ is a reference line connecting the leading edge and the trailing edge of the section at the center of the bucket 5, Z ₁ -Z ₂ is a reference line connecting the leading edge and the trailing edge of the cross section at the root of the rotor blade 5. Here, for the velocity V in the axial direction, there is a relation of V = V ₁ = V ₂ = V ₃ , and for the flow component T _{i in the} direction opposite to the rotation, the moving blade 5 Assuming that the distance (radius) from the axis at each of the cross-section of the tip, center, and root of the blade is R _i , T _i = 2 × π × R _i × N. 5 has the following relationship: T ₁ > T ₂ > T ₃ . The airflow that has flowed in from the leading edge of the rotor blade 5 has the reference lines X ₁ -X ₂ , Y ₁ -Y ₂ ,
The fluid flows out in the direction of the outflow angle θ _i (θ ₁ , θ ₂ , θ ₃ ) with respect to Z ₁ -Z ₂ , and the outflow angle θ _i depends on the work (or the generated lift) performed by the rotor blade 5 at each sectional position. ), The angle is generally large at the tip of the moving blade 5 and decreases toward the root, and θ _i = 0 when no work is performed like the root of the moving blade 5. ## EQU4 ## There is a relationship of θ ₁ > θ ₂ > θ ₃ (≒ 0). [0017] That is, uniform flow flowing along the axial direction (flow velocity V) is past the rotor blade 5 is changed the direction of the flow by the work of the animal blade 5, it flows out in the direction of the outflow angle theta _i Go. That is, due to the work performed by the rotor blades 5, the flow turns in the direction of the outflow angle θ _i and flows out. The relationship between the radius R _{i of the} rotor blade 5 and the outflow angle θ _i is as shown in FIG. In FIG. 3, θ _TIP is
Shows the outflow angle at the tip end. For this reason, for example, as shown in FIG. 4 (a), if the support leg 3 arranged behind the fan 6 is a curved plate having a twist, as shown in FIG. 4 (b),
Since each cross section of the support leg 3 is placed in accordance with the direction of the airflow flowing out from the cross section of the tip, the center, and the root of the rotor blade 5, the resistance is theoretically zero and the ideal. However, the support leg 3 needs a curved surface processing, which leads to an increase in cost, which is not preferable. On the other hand, for example, FIG.
As shown in FIG. 5 (b), when the support leg 3 disposed behind the fan 6 is a flat plate without twist and the mounting angle matches the outflow angle of the tip of the rotor blade 5, as shown in FIG.
Has a large angle of attack on the side of the shaft center (both shaft motor 4), but in this case, the resistance is suppressed to a small value without being so large because the flow velocity of the air flow is slow. Incidentally, for example, as shown in FIG. 6A, when the support leg 3 arranged behind the fan 6 is a flat plate without twist and the mounting angle matches the outflow angle of the root of the rotor blade 5, FIG. As shown in (b), the support leg 3 has a large angle of attack on the inner surface side of the casing 2, but in this case, the resistance is also increased due to the high flow velocity of the air flow. Therefore, in terms of hydrodynamics, it is most ideal that the support leg 3 is a curved plate having a twist as shown in FIG. 4, but in the embodiment of the present invention, the manufacturing cost is also reduced. As shown in FIG. 5, the support leg 3 of the two-axis motor 4 is formed in a flat plate shape, and its mounting angle matches the outflow angle of the airflow from the trailing edge of the tip of the rotor blade 5 of the fan 6 located at the front stage. Let it do. Next, the operation of the illustrated example will be described. As described above, the airfoil of the rotor blade 5 of the fan 6 has a streamlined shape, the work load of the rotor blade 5 of the fan 6 located at the front stage is 100%, and the fan located at the rear stage is located at the time of airflow generation. Assuming that the work load ratio of the moving blades 5 of the fan 6 is 0%, as in the conventional case, the wings of the moving blades 5 of the fan 6 use a symmetrical shape in which the back and front surfaces are circular and have no warpage. In contrast, the aerodynamic and noise characteristics are good, and it is possible to significantly increase efficiency and reduce noise in response to large air volume, and also to perform rotor reversal to realize the function of bidirectional air blowing with the same specifications by reverse rotation. There is no need to provide a mechanism, the overall structure is not complicated,
It is also possible to avoid an increase in cost, and furthermore, to make the support leg 3 of the two-axis motor 4 flat, and to make its mounting angle coincide with the outflow angle of the airflow from the trailing edge of the tip of the rotor blade 5 of the fan 6 located at the front stage. In addition, the resistance can be minimized without twisting the support leg 3. The jet fan 1 constructed as described above
In FIG. 7, when the angle of the rotor blade 5 is changed from the design value, the performance test results obtained by plotting the data at the time of normal rotation and reverse rotation are as shown in FIGS. 7A, 7B, and 7C. When the declination from the rotor blade angle is 0.0, that is, the rotor blade angle is a design value, the discharge air volume does not become lower than the lower limit of the specification value, and the shaft power does not exceed the upper limit of the specification value. , About 82 above the lower limit of its specification.
%. Further, as shown in FIG. 8, it was confirmed that the noise level could be reduced as compared with the conventional type. In this way, it is possible to achieve a significant increase in efficiency and a reduction in noise corresponding to a large air volume without providing a moving blade reversing mechanism or the like having a complicated structure. It should be noted that the jet fan of the present invention is not limited to the illustrated example described above, and it is needless to say that various changes can be made without departing from the spirit of the present invention. As described above, according to the jet fan of the present invention, it is possible to greatly increase the efficiency corresponding to a large air flow without providing a moving blade reversing mechanism or the like having a complicated structure. An excellent effect of reducing noise can be achieved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an airfoil arrangement and a speed triangle of front and rear rotor blades in an example of an embodiment of the present invention. FIG. 2 is a perspective view showing an inflow direction and an outflow direction of an airflow to one blade in an example of an embodiment of the present invention. FIG. 3 is a diagram showing a relationship between a radius of a moving blade and an outflow angle in an example of an embodiment of the present invention. FIG. 4 (a) is a view showing a case where a support leg arranged behind the fan is a curved plate with a twist, and FIG. 4 (b) is a view showing a case where the support leg arranged behind the fan is a curved plate with a twist. It is a figure which shows each cross section. FIG. 5 (a) is a view showing a case where a support leg disposed behind the fan is a flat plate having no twist and an attachment angle is made equal to an outflow angle of a blade tip, and FIG. 5 (b) is disposed behind the fan. FIG. 6 is a view showing each cross section when the supporting legs to be formed are flat plates without twist and the mounting angle is made to coincide with the outflow angle of the blade tip. FIG. 6 (a) is a view showing a case where the support legs arranged behind the fan are flat plates without twist and the mounting angle is matched to the outflow angle of the blade root, and FIG. 6 (b) is arranged behind the fan. FIG. 7 is a view showing each cross section when the supporting legs to be formed are flat plates without twist and the mounting angle is made to coincide with the outflow angle of the blade root portion. 7A and 7B are diagrams showing performance test results of an example of an embodiment of the present invention, in which FIG. 7A is a diagram showing a change in a discharge air amount with respect to a change in blade angle of a moving blade, and FIG. FIG. 7C is a diagram illustrating a change in shaft power with respect to a change in blade angle of the rotor blade, and FIG. 7C is a diagram illustrating a change in fan efficiency with respect to a change in blade angle of the rotor blade. FIG. 8 is a diagram showing a result of comparing a noise level of an example of an embodiment of the present invention with a conventional noise level. FIG. 9 is a perspective view showing an example of a general jet fan. [Description of Signs] 1 Jet fan 2 Casing 3 Support leg 4 Double shaft motor 5 Moving blade 6 Fan 7 Air flow 8 Air flow

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F04D 29/52 F04D 29/52 D F24F 7/06 F24F 7/06 FF Term (Reference) 3H032 AA04 CA02 CA08 NA05 3H033 AA02 BB02 BB08 BB20 CC01 CC07 DD03 EE06 EE14 EE19 3H034 AA02 BB02 BB08 CC01 CC07 DD27 DD28 EE06 EE12 EE18 3L058 BD01 BE08

Claims (1)

Claims: 1. A cylindrical casing attached to a ceiling of a tunnel, a two-axis motor disposed concentrically by supporting legs in the casing, and a A fan fitted to each shaft and having a rotor blade, by rotating the dual-axis motor forward or reverse,
In a jet fan that generates airflow in the forward or reverse direction, the airfoil of the blade of the fan is made streamlined, and the work load of the rotor blade of the fan located at the preceding stage when the airflow is generated is 100%.
And the work load ratio of the rotor blade of the fan
A jet fan, wherein the support legs of the two-axis motor are formed in a flat plate shape, and the mounting angle thereof is made to coincide with the outflow angle of the airflow from the trailing edge of the tip of the rotor blade of the fan located at the front stage.