JPH0658116B2 - Blower - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air blower using a mixed flow impeller used in an air conditioner or the like.

Conventional technology Conventionally, a mixed flow diffuser that discharges in the direction along the inclination of the hub is often used for mixed flow impellers, and the shape of the blades is determined using the diagrams and empirical formulas shown by Stepanov and Fredera. Has been designed. The procedure will be described with reference to the drawings. As shown in FIG. 5, the meridian shape of the blade 1 is determined, and the flow path from the hub 2 to the tip 3 is divided into a plurality of flow paths so that the flow rate becomes equal. The equal flow rate dividing line 4 is used as a generatrix, and a conical surface obtained by rotating around the central axis is considered as a rotating flow surface, and the warp line of the blade is determined based on the two-dimensional flow on this surface. To explain with reference to development of the rotating flow surfaces (Figure 6), when the inlet entrance angle beta ₁ of inflow angle beta _'1 and the blade of air greatly deviate the air does not flow along the blade, it is disturbed It becomes large and the performance deteriorates. Therefore,
It is general to determine β ₁ so as to almost coincide with β ′ ₁ . Normally, beta _'1 is the rotational speed of the impeller, so using the values deduced from the flow rate and inlet radius, beta ₁ is large at the hub side to by that shown in FIG. 7 by the radius r, smaller chip side To change.

On the other hand, the blade outlet angle β ₂ is determined so as to satisfy the required total pressure increase. That is, when the flow shown in FIG. 6 is generated, the total pressure head ΔHt is However, η ... Efficiency g ... Gravitational acceleration (m / sec ² ), Cu2 ... Circumferential component of absolute velocity (m / sec) U _2, ... Here, Cu ₂ is represented by the following equation.

Cu ₂ = U ₂ −Cm ₂ / tan β ₂ However, Cm ₂ ... Radial direction component of absolute velocity (m / sec) Therefore, if flow rate, rotation speed, total pressure head and radial position are determined, η should be properly assumed. Yields β ₂ . Similar to β ₁ described above, β _{2 is} also large on the hub side and small on the tip side in a general mixed flow impeller.

Next, on the developed surface, the inlet side and the outlet side are connected by a single arc so as to satisfy the above β ₁ and β ₂ , and this is used as the warp line of the blade.

As described above, the shape of the blade warp line determined on one rotating flow surface was determined on each rotating flow surface from the hub to the tip, and the blade shape was determined by connecting them smoothly. .

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, when a centrifugal diffuser that discharges a flow in a radial direction is used, the entire flow between blades is more
As the radial component of the flow increases, the mixed flow impeller designed for the mixed flow diffuser as described above could not exhibit sufficient performance. That is, using a centrifugal diffuser reduces the flow rate on the hub side of the impeller,
The flow rate on the tip side tends to increase. Therefore, there is a problem that flow separation is likely to occur on the hub side, and an effective head cannot be obtained on the chip side, resulting in deterioration of performance.

The present invention solves such a conventional problem, and an object of the present invention is to provide a mixed flow impeller that exhibits optimum performance when combined with a centrifugal diffuser.

Means for Solving the Problems In order to solve the above problems, a blower device of the present invention includes a substantially frustoconical hub and a plurality of blades provided on an inclined surface of the hub, and an inlet angle of the blade. Is smaller from the hub side to the tip side, the exit angle is almost constant from the hub side to the tip side, and the flow line from the mixed flow impeller with the curved line from the leading edge to the trailing edge of the blade is a circular arc curve. The centrifugal diffuser which discharges in the radial direction is combined.

Operation In the impeller of the present invention, the outlet angle of the blade is substantially constant from the hub to the tip, so that it is smaller on the hub side and larger on the tip side than the conventional outlet angle. on the other hand,
When a centrifugal diffuser is used, the flow rate distribution between blades tends to be small on the hub side and large on the tip side. Therefore, the outlet angle becomes smaller when the flow rate decreases and becomes larger when the flow rate increases, so that the effective head does not change much and high performance can be obtained.

Embodiments Embodiments of the present invention will be described below with reference to the accompanying drawings. In FIG. 1, 5 is a mixed flow impeller, 6 is a hub, and 7
Is a feather. When the mixed flow impeller is driven by the motor 8, air flows in through the suction port 9 as indicated by the arrow a,
After passing through the mixed flow impeller 5, the centrifugal diffuser portion 10 is bent in the radial direction and discharged to the outside.

FIG. 2 compares the exit angle of the mixed flow impeller of the present invention and the exit angle of the conventional mixed flow impeller with the radius R.
Since the outlet angle in the present invention is almost constant from the hub side to the tip side, it is smaller on the hub side and larger on the tip side as compared with the conventional example. The relationship between these angle changes and the flow rate changes between the blades will be described with reference to FIGS. 3 (a) and 3 (b). First, looking at the hub side, the flow rate is reduced by using a centrifugal diffuser, so Cm ₂ *
Changes to. However, since the outlet angle β _{2 is} also as small as β ₂ *, the circumferential component Cu ₂ of the absolute velocity hardly changes and the optimum flow state is maintained. On the other hand, FIG. 3 (b)
As for the tip side shown in Fig. ₂ , since the flow rate on the tip side is increased by the centrifugal diffuser, Cm ₂ is equal to Cm ₂
Since the outlet angle β ₂ also increases to β ₂ * as it increases with *, Cu ₂ does not change so much, and the optimum flow is maintained.

FIG. 4 shows a graph comparing the characteristics of the solid line of the mixed flow impeller of the present invention and the broken line of the conventional mixed flow impeller. According to this figure, it is understood that the mixed flow impeller of the present invention exhibits the same or higher performance as the conventional one in the entire flow rate range.

Effect of the Invention As described above, in the mixed-flow fan of the present invention, by making the blade outlet angle almost constant, the flow rate on the hub side is reduced by using the centrifugal diffuser, and it is optimal even when the flow rate on the tip side is reduced. Since such a flow state can be maintained, the effect that the performance of the impeller is sufficiently exhibited is obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of an air blower according to an embodiment of the present invention,
FIG. 2 is a characteristic diagram showing a comparison between the exit angle of the mixed flow impeller of the present invention and the exit angle of the conventional example depending on the radius R, and FIG.
(a) is a characteristic diagram of changes in the flow rate and outlet angle on the hub side, FIG. 3 (b) is the same characteristic diagram on the tip side, and FIG. 4 compares the characteristics of the air blower of the present invention and the conventional air blower. Characteristic diagram,
FIG. 5 is a meridian diagram of a mixed flow impeller, FIG. 6 is a development diagram of a rotating flow surface for explaining a method of determining a curved line of a blade, and FIG. 7 is a characteristic diagram showing a change of an inlet angle with a radius R. is there. 5 ... Mixed flow impeller, 6 ... Hub, 7 ... Blade, 9 ... Suction port, 10 ... Centrifugal diffuser part,

Claims (1)

[Claims] 1. A hub having a substantially frusto-conical shape and a plurality of blades provided on the slope of the hub. The inlet angle of the blade is reduced from the hub side toward the tip side, and the outlet angle is measured from the hub side. A suction port is provided on the suction side of the mixed flow impeller with the curvature line from the front edge to the rear edge of the vane being one arc curve, and on the discharge side, the flow that flows in the axial direction. An air blower having a centrifugal diffuser portion that bends and discharges air.