Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D29/00—Details, component parts, or accessories
  • F04D29/40—Casings; Connections of working fluid
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
  • F04D17/00—Radial-flow pumps, e.g. centrifugal pumps; Helico-centrifugal pumps
  • F04D17/08—Centrifugal pumps
  • F04D17/16—Centrifugal pumps for displacing without appreciable compression
  • F04D17/161—Shear force pumps

Definitions

• the present invention relates to a multiblade centrifugal fan.
• a multi-blade centrifugal fan having a large number of blades arranged at intervals in the circumferential direction such as a sirocco fan, a turbo fan, and a radial alpha fan, is known.
• noise due to the separation of fluid at the leading edge of the blade due to the difference between the inflow angle of the fluid into the leading edge of the blade (the inner diameter of the impeller) and the mounting angle of the blade
• Noise due to the separation of fluid in the flow path between the blades of the impeller noise due to the difference between the outflow angle of the fluid from the impeller and the spread angle of the casing, and interference noise between the tongue of the casing and the blade.
• Fig. 18 (a) The separation of the fluid at the leading edge of the wing is as shown in Fig. 18 (a). Because the wing is rotating with respect to the fluid flowing into the leading edge of the wing almost in the absolute coordinate system in the radial direction. As shown in Fig. 18 (b), in the relative coordinate system viewed from the wing, the fluid is at an angle to the extension direction of the leading edge of the wing, This is caused by the difference between the inlet angle and the blade mounting angle.
• the present invention has been made in view of the above problems, and has an angle of wing attachment.
• the difference between the inflow angle of the fluid into the leading edge of the wing and the mounting angle of the wing can be reduced without any change in the wing leading edge, and the noise due to the separation of the fluid at the leading edge of the wing can be reduced.
• the purpose is to provide a multi-blade centrifugal fan.
• a multi-blade centrifugal fan having a large number of blades arranged at intervals in a circumferential direction
• a multi-blade centrifugal fan comprising: a large number of annular plates laminated at a small interval in the axial direction of the centrifugal fan.
• a flow path formed between a number of annular plates that are arranged radially inward of the blade and that are stacked at a minute interval from each other in the axial direction of the multiblade centrifugal fan, During the passage of the fluid radially outward, the fluid is accelerated by tangential shearing forces from the rotating toroidal plate and is imparted with tangential velocity. Fluid with tangential velocity flows into the flow path formed between adjacent wings.
• the tangential velocity of the fluid is imparted by the annular plates that are arranged radially inside the wing, and the difference between the circumferential velocity of the leading edge of the wing and the tangential velocity of the fluid is As a result, the difference between the inflow angle of the fluid to the leading edge of the blade and the mounting angle of the blade is smaller than that of the multi-blade centrifugal fan without the circular plate. Reduced compared to centrifugal fan.
• the multiple blade centrifugal centrifugal centrifugal centrifugal fan according to the present invention can be provided by incorporating the annular plate into an existing multiblade centrifugal fan. There is an advantage that fans can be easily created.
• the outer surface of the annular plate is spaced radially inward from the leading edge of the blade.
• the outer edge of the annular plate abuts the leading edge of the wing.
• the outer edge of the annular plate overlaps the leading edge of the wing.
• the outer edge of the annular plate abuts the leading edge of the wing, or if the outer edge of the annular plate overlaps the leading edge of the wing, it flows radially outward from the flow path between the annular plates. Fluid flows into the leading edge of the wing without losing the tangential velocity component, which reduces the difference between the angle of fluid flow into the leading edge of the wing and the mounting angle of the wing.
• the outer edge of the plate abuts on the leading edge of the wing. Or, the outer edge of the annular plate overlaps the leading edge of the wing, which has the advantage of increasing the strength of the multi-blade centrifugal fan.
• the wing is a radial wing.
• the wing is a swept wing.
• the wing is a forward wing.
• the wing is a radial wing (radial), a swept wing (evening-bofan) or a forward wing (sirocco fan)
• radial radial
• swept wing evening-bofan
• forward wing forward wing
• FIG. 1 is a cross-sectional view of a multi-blade radial fan according to an embodiment of the present invention
• FIG. 2 is a cross-sectional view taken along line II-II of FIG.
• Fig. 3 is a cross-sectional view of a multi-blade radial alphan illustrating the difference between the air inflow angle to the leading edge of the blade and the mounting angle of the blade.
• Fig. 4 shows the outline of the experimental device for measuring air volume and static pressure.
• Fig. 5 shows the outline of the experimental device for noise measurement.
• Fig. 6 (a) is a plan view showing the configuration of a trial impeller (radial fan) having no laminated annular plate
• Fig. 6 (b) is a view taken along the line bb in Fig. 6 (a)
• FIG. 7 (a) is a plan view showing a configuration of a trial impeller (radial alpha) having a laminated annular plate
• FIG. 7 (b) is a view taken along the line b_b in FIG. 7 (a)
• FIG. 8 is a plan view of the trial casing (Rajiarufu ⁇ down) in FIG. 9 is a minimum specific noise Ks mi n obtained by the noise measurement, the mounting angle of the inflow angle and airfoil of air to the wing leading edge
• FIG. 10 (a) is a cross-sectional view showing the configuration of a sample impeller (silicon fan) having no laminated annular plate
• Fig. 11 (a) is a cross-sectional view showing the configuration of a trial impeller (silicon fan) having a laminated annular plate
• Fig. 11 (b) is a trial impeller having a laminated annular plate. Sectional view showing the configuration of
• Fig. 12 is a plan view of a sample casing (silicon fan)
• Fig. 13 is a plan view of a sample casing (turbo fan)
• Fig. 14 is a silicon casing having a laminated annular plate. Figure comparing the noise of the fan with the noise of the sirocco fan without the laminated annular plate (impeller rotation speed 5100 rpm)
• Figure 15 compares the noise of a sirocco fan with a laminated annular plate with the noise of a sirocco fan without a laminated annular plate (the impeller rotation speed of 6120 rpm :).
• Fig. 16 compares the noise of a turbofan with a laminated circular plate and the noise of a turbofan without a laminated circular plate. Number 5 100 rpm),
• Fig. 17 compares the noise of a turbofan with a laminated circular plate with the noise of a sunset fan without a laminated circular plate (the rotational speed of the impeller is 6120 rpm).
• Fig. 18 (a) and Fig. 18 (b) are cross-sectional views of a multi-blade centrifugal fan explaining the reason for the difference between the inflow angle of fluid to the leading edge of the blade and the mounting angle of the blade. is there.
• reference numeral 1 denotes a disk-shaped base plate.
• annular top plate 2 is provided above the base plate 1 in parallel with the base plate 1. Located concentric with Spray 1.
• the base plate 1 and the top plate 2 are connected by a large number of radial wings 3 arranged at intervals in the circumferential direction.
• a plurality of annular plates 4 are arranged in a radially inward direction of the radial wings 3 at a small interval from each other, in parallel with the base plate 1 and concentrically with the base plate 1. ing.
• the outer edge of the annular plate 4 fits tightly into a horizontal slit formed on the inner edge of the radial wing 3.
• An impeller 5 is formed by the base plate 1, the top plate 2, the radial wings 3, and the annular plate 4.
• the central opening 5a of the impeller 5 is formed by the central opening of the stacked annular plates 4. Circles between base plate 1 and lowermost annular plate 4, between top plate 2 and uppermost annular plate 4, and between adjacent annular plates 4.
• An inter-plate flow path 5b is formed, and an inter-blade flow path 5c is formed between adjacent radial blades 3.
• the impeller 5 is housed in a casing 6 having a scroll-shaped flat cross section.
• a suction port 6a is formed in the top plate of the casing 6 so as to face the central opening 5a of the impeller.
• a discharge channel 7 is formed between a side edge of the impeller 5 and a side wall of the casing 6.
• a motor 8 is provided below the casing 6.
• the motor 8 is fixed to the bottom plate of the casing 6.
• the output shaft of the motor 8 extends upward through the bottom plate of the casing 6 and is fixed to the center of the lower surface of the base plate 1
• the fluid When the motor 8 starts, the fluid is sucked into the casing 6 through the suction port 6 a of the casing 6.
• the fluid sucked into the casing 6 flows into the flow path 5b between the annular plates.
• the fluid that has flowed into the inter-plate flow path 5b is passed radially outward through the inter-plate flow path 5b.
• the rotating base plate 1, the top plate 2, and the ring As shown by the double arrow in FIG. 2, the plate 4 is accelerated by receiving a tangential shear force, is given a tangential speed, and is provided with a centrifugal force.
• the fluid that has passed through 5b flows into interblade flow path 5c.
• the fluid flowing into the inter-blade flow path 5c passes through the inter-blade flow path 5c in a radially outward direction from the rotating radial blade 3 as shown by an arrow in FIG. It is further accelerated by receiving a force in the direction normal to the facing wing 3. A larger centrifugal force is applied.
• the fluid that has passed through the inter-blade channel 5 c flows into the discharge channel 7 from the outer edge of the inter-blade channel 5 c, that is, from the outer edge of the impeller 5.
• Discharge channel The fluid flowing into the inside 7 flows in the circumferential direction in the discharge channel 7 ⁇ , and is discharged from the casing 6 through the discharge port 6b.
• the fluid in the flow path 5b between the annular plates is accelerated tangentially by the base plate 1, the top plate 2, and the annular plate 4, and the tangential velocity is given.
• the difference between the circumferential velocity of the leading edge of the radial blade 3 and the tangential velocity of the fluid is increased. It is reduced compared to a multi-blade radial fan without the annular plate 4 arranged.
• the difference between the angle of fluid inflow to the leading edge of the radial wing 3 and the mounting angle of the wing is smaller than that of a multi-blade radial fan without the circularly arranged annular plate 4. Therefore, noise due to fluid separation at the leading edge of the radial wing 3 is reduced.
• the outer edge of the annular plate 4 is tightly fitted in a horizontal slit formed on the inner edge of the radial wing 3, so that the multi-blade radial alpha has high strength.
• the comparative measurement of noise was carried out for the multi-blade radial fan according to the present example and the multi-blade radial fan that does not have the annular plate arranged in a stack.
• the radial direction of the fan is at an angle of 0 °
• the mounting angle of the leading edge of the multi-blade centrifugal fan is ⁇
• the fluid inflow angle to the leading edge of the blade is yS. .
• Equation (2) The difference 0 between the inflow angle / 8 of the fluid into the leading edge of the blade of the multiblade centrifugal fan and the mounting angle of the leading edge of the blade of the multiblade centrifugal fan is given by Equation (2).
• the tangential velocity of the fluid between the stacked annular plates to the annular plate is derived by Hasinger (Hasinger, S. and Kehrt. L., Trans. ASME. J. Eng. Power, 85 (1 963). 201)). According to Hasinger, the tangential velocity v k of the fluid with respect to the annular plate at the outer edge of the annular plate is given by the formula 2.
• a circular plate is arranged radially inward of the leading edge of the wing, and if the outer edge of the circular plate is in contact with the leading edge of the wing, The angle difference 0 is given by equation (3).
• the multi-blade radial alphan according to the present embodiment and the stacked circles The noise was compared and measured for a multi-blade radialphan without a ring plate, and the relationship between the minimum specific noise and the angle difference of 0 was obtained.
• FIG. 4 shows the experimental setup.
• a suction nozzle is installed on the suction side of the fan body that includes the impeller 5, the scroll casing 6 that houses the impeller 5, and the motor 8, and a double chamber air flow meter (Rika Seiki) is installed on the discharge side of the fan body.
• Model F-401 was installed.
• the airflow measuring device was provided with a damper for adjusting the airflow and an auxiliary fan to control the static pressure at the fan outlet.
• the air flow from the fan was rectified by the rectifying grid.
• the air flow rate of the fan discharge air was measured with an orifice installed in accordance with the AMCA standard, and the static pressure at the fan outlet was measured with a static pressure hole located near the fan outlet.
• Figure 5 shows the experimental setup.
• a suction nozzle was installed on the suction side of the fan body, and a static pressure adjustment box approximately the same size and shape as the air flow measurement device was installed on the discharge side of the fan body.
• the static pressure adjustment box is lined with sound absorbing material.
• the static pressure adjustment box was equipped with a damper for adjusting the air flow, and the static pressure at the fan outlet was controlled.
• the static pressure at the fan outlet was measured by a static pressure hole arranged near the fan outlet, and the noise at a predetermined fan outlet static pressure was measured.
• the motor 8 was housed in a soundproof box lined with sound absorbing material, and the noise of the motor 8 was cut off.
• the noise was measured in the anechoic room at a point 1 m upstream from the upper surface of the casing, on the center line of the fan shaft, and the A-weighted noise level was measured.
• the outer diameter (diameter at the trailing edge of the radial wing 3) is 10 O mm.
• the impeller height is fixed at 24 mm, and the plate thickness of the base plate 1 and the top plate 2 is 2 mm.
• the three types of impellers 5 without the laminated annular plate 4 were created, where the ratio between the inner diameter (diameter at the leading edge position of the radial wing 3) and the outer diameter and the number of radial wings 3 were different.
• Table 1 and Figs. 6 (a) and 6 (b) show the specifications of the above three types of impellers 5 (impellers N O. 1, 2, 3).
• Inner diameter Leading edge of radial wing 3 with outer diameter fixed to 100 mm and impeller height fixed to 24 mm, and base plate 1 and top plate 2 set to 2 mm thickness
• Three types of impellers 5 having a laminated annular plate 4 having different ratios of the diameter at the position) to the outer diameter, the inner diameter of the annular plate 4, and the number of the annular plates 4 were created.
• the height of the casing 6 was set to 27 mm, the spreading shape of the casing 6 was set to a logarithmic spiral shape given by the following equation, and the spreading angle 7 e was set to 4.5 °.
• Sample casing 6 is shown in FIG.
• the six types of impellers 5 shown in Table 1 and the rotation speeds shown in Table 1 are used.
• the air flow is adjusted in various ways by a damper for air flow adjustment to change the air flow of the fan discharge air and the static pressure at the fan outlet. And noise.
• the specific noise k was calculated based on the following equation from the measured values of the fan discharge air volume, the fan outlet static pressure, and noise.
• Ks SPL (A)-1 0 logjo Q (P,) 2
• SPL (A) A characteristic (: up to 20 KHz), 1 Z 3 octaves
• the relationship between the specific noise Ks and the air volume is that the air volume, the air volume obtained by the static pressure measurement, and the static pressure at the fan outlet are 1 respectively, and the specific noise obtained by the noise measurement and the static air at the fan outlet are 1.
• the pressure is
• the specific noise Ks of each sample impeller 5 changes according to the change in the airflow. This change in the specific noise Ks is caused by the influence of the casing, and the lowest value of the specific noise Ks, that is, the lowest specific noise Ks min, is the sample impeller from which the influence of casing is removed. 5 It is considered to indicate its own noise characteristics.
• That minimum specific noise Ks mi n is considered to be free of noise caused by the difference between the spread Ri corner of outflow angle and Ke one single fluid from the impeller.
• the relationship with Z, is in the silent region proposed in the above application for all the sample impellers 5 (the dimensionless number Z! Of Kalman-Milican is shown in Table 1). Therefore, it is considered that the lowest specific noise Ksw does not include noise due to fluid separation in the flow path between the blades of the impeller.
• the minimum specific noise Ks Bi n is considered to represent the noise characteristic that by the ⁇ of air at the blade leading edge due to the difference between the inflow angle and the blade attaching angle of the air into the blade leading edge portion Can be
• each trial impellers minimum ratio of 5 noise Ks ffli "and shows the relationship between the angle difference of 0 in FIG. 9.
• the angle difference 0 the inner diameter (diameter of the outer diameter of the annular plate 4 (2 r k) is an impeller At the leading edge position of facing wing 3 Diameter).
• the angle difference 6 »of the trial impeller 5 (NO 4, 5, 6) having the laminated annular plate is the difference between the sample impeller 5 (NO. 1, 2) without the laminated annular plate. , 3) is smaller than the angle difference of 0, and it can be seen that a reduction in the minimum specific noise Ks mi n with decreasing angular difference 0, the above-mentioned noise measurement results, the present invention is, vane leading edge It was confirmed that it was effective in reducing the noise of the multi-blade centrifugal fan due to the separation of the fluid at the leading edge of the blade due to the difference between the flow angle of the fluid into the blade and the mounting angle of the blade.
• the same apparatus as the experimental apparatus of the first embodiment was used for both the experimental apparatus for measuring air volume and static pressure and the experimental apparatus for measuring noise.
• the height of the casing is defined as the impeller height (height between blades + base plate thickness + top plate thickness) + 9 mm.
• the height of the impeller is (height between the blades + base plate thickness + top plate thickness) + 8 mm, and the casing spreading shape is the logarithm given by the following equation. The shape was helical and the divergence angle was 4.5 °.
• rc radius r of the casing side wall measured from the center of impeller 5. : Outer radius of impeller 5
• T Angle from the reference line 0 ⁇ 7 ⁇ 2 7:
• Fig. 12 shows a trial casing for impellers N O.1 and N.O. 3 (Sirocco fan), and a trial casing for impellers NO. 2 and NO. 4 (Evening-Bofan).
• the casing is shown in FIG. 4 Impeller rotation speed
• the number of revolutions of the impeller was set at 5100 rpm and 6120 rpm.
• the relationship between the specific noise Ks and the flow coefficient ⁇ was determined from the relationship between the specific noise Ks and the air volume Q and the flow coefficient 0 obtained from the air volume Q.
• Fig. 14 to Fig. 17 show the relationship between the specific noise Ks and the flow coefficient ⁇ .
• the turbocharger can be used for sirocco fans. Also in the fan, it can be seen that the noise is reduced over a wide range of flow coefficient by arranging the laminated annular plate inside the impeller.
• the above-mentioned noise reduction is achieved by suppressing the separation of fluid at the leading edge of the wing, reducing the noise, and suppressing the separation of fluid at the leading edge of the wing.
• the leading edge of the blade, the suppression of the separation of fluid in the inter-blade flow path, and the uniform velocity distribution in the circumferential direction of the outflow air at the inter-blade flow path outlet make the tongue of the casing and the wing It is considered that reduction of interference noise was achieved by superimposition. O.
• the present invention is also effective for sirocco fan and evening bofan.
• the outer edge of the annular plate 4 of the multi-blade radial fan impeller according to the first embodiment may be spaced radially inward from the leading edge of the radial wing 3, or It may be in contact with the edge.
• the existing multi-blade radial By incorporating the annular plate into the fan, there is an advantage that the multiblade radial fan according to the present invention can be easily produced.
• the annular shape is the same as when the outer edge of the annular plate 4 overlaps the leading edge of the radial wing 3.
• the fluid flowing radially outward from the flow path between the plates 4 flows into the leading edge of the radial wing 3 without losing the tangential velocity component, so that the leading edge of the radial wing 3
• the abutment between the outer edge of the annular plate 4 and the leading edge of the radial wings 3 is soldered or bonded.
• the advantage of being fixed by such a method is that a high-strength multi-blade radialphan can be obtained, as in the case where the outer edge of the annular plate 4 overlaps the leading edge of the radial wing 3. .
• annular plates 4 may be laminated and provided only on the portion closer to the base plate 1 or only on the portion closer to the top plate 2 or at the intermediate portion.
• the difference between the inflow angle of the fluid to the leading edge of the blade and the mounting angle of the blade can be reduced without changing the mounting angle of the blade, and the fluid at the leading edge of the blade can be reduced.
• a multi-blade centrifugal fan with reduced noise due to separation is provided.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Structures Of Non-Positive Displacement Pumps (AREA)

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Citations (1)

• 1995
  • 1995-06-30 WO PCT/JP1995/001307 patent/WO1996000854A1/ja not_active Application Discontinuation
  • 1995-06-30 CA CA002168551A patent/CA2168551A1/en not_active Abandoned
  • 1995-06-30 EP EP95923554A patent/EP0717194A1/en not_active Withdrawn
  • 1995-06-30 KR KR1019960700637A patent/KR960704162A/ko not_active Abandoned
  • 1995-07-04 TW TW084106891A patent/TW268078B/zh active

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