JPH1010004A - Circulating water tank with low noise ring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize the bad effect on acoustic measurement by a fluid noise as much as possible by providing a low noise ring having a radius smaller than an impeller on the upstream side of the impeller so as to be concentrically adjacent thereto SOLUTION: In a circulating water tank 1, a circulating passage of water producing a flow within a measuring part 1a is formed by an inlet pipe line 1b, a discharge pipe line 1c, a communicating pipe line 1d and each corner part 1e. An impeller 2 for producing a water flow is mounted on the inner part of the pipe line 1e, and the impeller shaft 2b of the impeller 2 is extended to the outside of the pipe line 1d, and connected to a motor 2a set on the outside lower part of the pipe line 1c. A low noise ring 3 is provided adjacently on the upstream side of the impeller 2, and the ring 3 is arranged concentrically to the impeller 2. Thus, the circulating water is rectified by the ring 3 and entered into the impeller 2, by which the resistance with the impeller 2 in rotation is reduced to reduce the water flow noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the measurement of sound caused by an object placed in a water flow of a measuring unit by forcibly circulating water in a water tank with an impeller to generate a water flow in a fixed direction in the measuring unit. In particular, the fluid noise generated by the impeller when the water is forcibly circulated is reduced as much as possible by a low-noise ring provided near the impeller upstream side, and the fluid noise is reduced. The present invention relates to a circulating water tank provided with a low-noise ring that minimizes an adverse effect on sound measured by a measuring unit.

[0002]

2. Description of the Related Art Conventionally, water in a water tank is forcibly circulated using, for example, an impeller or the like to generate a water flow in a fixed direction in a measurement unit, and a sound caused by an object placed in the water flow of the measurement unit is measured. A circulating water tank used to perform the water circulation is known.

The circulating water tank has a structure in which water in the water tank is forcibly circulated to generate a water flow in a fixed direction in the measuring section. That is, the circulation water tank is provided with a communication pipe for circulation, for example, below the bottom of the measurement unit, and both ends of the communication pipe are bent upward and connected to both side surfaces of the measurement unit, and the communication pipe is connected to the communication pipe. For example, an impeller for forcibly circulating water is provided inside the pipe.

In the circulating water tank, the impeller is driven to force water to flow into the measuring section from one side of the measuring section, and to flow out of water from the other side of the measuring section. The water is circulated and flown again into the measuring section to generate a water flow in a fixed direction in the measuring section.

[0005]

By the way, in an experiment in which a sound caused by an object placed in the water flow of the measuring unit is measured using a circulating water tank, noise is generated. There are the following causes. (1) Noise generated by axial flow pumps (impeller and stator) for generating water flow (2) Fluid noise generated by guide vanes (guide vanes) (3) Turbulent noise generated in water tank (including boundary layer noise) (4) Noise generated by mechanical vibrations of guide vanes, tank outer plates, etc. (5) Noise generated by drive motor and drive shaft system Among these, (1), (2) and (3) are fluid noise, and (4),
(5) is mechanical noise. The largest noise level in the fluid noise is the fluid noise generated by the impeller in (1).

The sound wave of the noise generated by the impeller (also in the case of the stator) reaches the measuring section while mainly reflecting each corner of the circulating water tank, and adversely affects the evaluation of acoustic measurement in the measuring section. there were.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made in order to solve the problems. It is an object of the present invention to reduce fluid noise generated by an impeller when water is forcedly circulated. Circulation with a low-noise ring that can minimize the adverse effect of fluid noise on the evaluation of acoustic measurement in the measurement unit by reducing the noise as much as possible by a low-noise ring provided close to the upstream side To provide an aquarium.

[0008]

In order to achieve the above object, the present invention forcibly circulates water in a water tank with an impeller to generate a water flow in a fixed direction in a measuring section, and In a circulating water tank for measuring a sound caused by an object placed in a water flow, a circulating water tank is provided with a low noise ring having a radius smaller than the impeller and provided concentrically close to the impeller upstream.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically based on embodiments of the invention shown in the drawings. Here, FIG. 1 is a schematic overall sectional side view of the circulating water tank, and FIG. 2 is an enlarged sectional side view of an upper half of a main part.

In the figure, a circulating water tank provided with a low-noise ring is a device for forcibly circulating the water in the water tank to generate a water flow in a certain direction in the water tank, and forcibly circulating the water in the water tank. And a low-noise ring 3 provided concentrically adjacent to the upstream side of the impeller.

The circulating water tank 1 is, for example, a vertical type, that is, a circulating water tank that circulates up and down. On the upper side of the circulating water tank, an acoustic object caused by an object placed in a water flow with an experimental object floating or submerged. Is provided.

An inlet for water circulating into the measuring section 1a is opened on one side in the longitudinal direction of the measuring section 1a.
Further, a discharge port for discharging water flowing through the inside of the measuring section 1a is opened on a side opposite to the inflow port. The inflow pipe 1 is located outside both ends of the measuring section 1a where the inlet and outlet are formed.
b and a discharge line 1c are provided respectively.

The inflow conduit 1b and the discharge conduit 1c are formed with corner portions 1e, 1e, each of which has a distal end curved downward by about 90 degrees, and are curved downward. Are formed at the corners 1e, 1e, which are curved by about 90 degrees toward the inward horizontal direction, and are connected to the end of a communication pipe 1d provided below the measuring section 1a.

The circulating water tank 1 forms a circulation path of water for causing a flow in the measuring section 1a by the inflow pipe 1b, the discharge pipe 1c, the communication pipe 1d, and each corner 1e. Is done.

An impeller 2 for generating a water flow is mounted inside the communication pipe 1d. The impeller shaft 2b of the impeller 2 extends outside the communication pipe 1d,
The motor 2a is operatively connected to a motor 2a installed at a lower portion of the outside of the discharge pipe 1c. The impeller 2 is one of the major causes of fluid noise.

Therefore, in order to reduce the fluid noise generated in the impeller 2, a low noise ring 3 is provided upstream of the impeller 2.
Are provided close to each other. That is, they are provided with a slight gap that does not contact the upstream side of the impeller 2. The low noise ring 3 is provided concentrically with the impeller 2.

The impeller 2 is mounted such that the gap between the tip of the impeller and the inner peripheral surface of the communication pipe 1d is very small. The low noise ring 3 has a radius smaller than that of the impeller 2. Consists of The low noise ring 3 is formed with a small thickness.

Further, the dimensions of the gap C _r of the axial length L _s of the low noise ring 3, and the ring inner peripheral surface to the inner circumferential surface of the communication duct 1d, the table in relation such as: Is done. _{L s / S = 2.1~ 4.0 C} r /S=0.19 here, S: the length of the blades of the impeller 2

By providing the low noise ring 3 upstream of the impeller 2, water entering the impeller 2 is rectified by the low noise ring 3, and the noise generated by the impeller 2 can be reduced. it can.

A guide vane 4 is provided at each corner 1e of the circulating water tank 1. The guide vane 4 functions to smoothly change the flow direction of water at the corner 1e. The guide vanes 4 have been subjected to a sound absorbing process so that sound waves are not reflected. A stator 5 is provided on the downstream side of the impeller 2 in close proximity.

Next, the operation based on the configuration of the above embodiment of the present invention will be described below. Measuring part 1a of circulating water tank 1
The motor 2a is driven to generate a water flow. When the motor 2a is driven, the impeller 2 in the communication pipe 1d rotates to pump water in the communication pipe 1d to the inflow pipe 1b through the corner 1e. The water pressure-fed from the communication pipe 1d to the inflow pipe 1b via the corner 1e flows through the inflow pipe 1b, and flows into the measuring section 1a from the downstream inlet of the inflow pipe 1b.

The water that has flowed into the measuring section 1a flows at a constant flow rate toward the discharge port on the opposite side. Therefore, the measuring unit 1
A water flow in a certain direction is generated in a. In the measurement unit 1a, acoustic measurement caused by an object placed in a water flow is performed in a state where the object for experiment is floating or submerged.

The water that has caused a constant water flow in the measuring section 1a is discharged from the discharge port into the discharge pipe 1c, and is discharged from the discharge pipe 1c.
c into the communication conduit 1d, where the impeller 2
Thus, it is circulated and pumped to the inflow pipe 1b via the corner 1e.

By the way, since the low noise ring 3 is provided close to the upstream of the impeller 2 for forcibly circulating the water in the circulation water tank 1, the circulating water is rectified by the low noise ring 3 and Therefore, the resistance to the rotating impeller 2 is reduced, and the water flow noise generated by the impeller 2 is greatly reduced.

The reduced fluid noise proceeds toward the downstream side of the impeller 2, and the corners 1e provided on the way are provided.
The guide vane 4 travels while being reflected, but since the reflected guide vane 4 is subjected to sound absorption processing, the sound is absorbed, weakened, and attenuated each time it is reflected.

It should be noted that the present invention is not limited to the above embodiment of the present invention, and it is needless to say that various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, the case where the circulating water tank 1 is composed of a vertical type, that is, a circulating water tank that circulates vertically is described. However, the present invention is not limited to this, and the circulating water tank 1 circulates horizontally. A circulating water tank may be used.

[0027]

As is apparent from the above description, according to the circulating water tank provided with the low-noise ring according to the present invention, the water in the water tank is forcibly circulated by the impeller, so that the water in the fixed direction in the measuring section. In the circulating water tank that generates a water flow and measures the sound caused by an object placed in the water flow of the measurement unit, a low noise ring with a radius smaller than the impeller is provided concentrically close to the impeller upstream side, so that water The fluid noise generated by the impeller when forced circulation is reduced as much as possible by the rectification function of the low-noise ring provided close to the impeller upstream side. The adverse effect on the evaluation of can be minimized.

[Brief description of the drawings]

FIG. 1 is a schematic overall sectional side view of a circulating water tank showing an embodiment of the present invention.

FIG. 2 is an enlarged side sectional view of an upper half of a main part showing the embodiment of the present invention.

[Explanation of symbols]

 1 water tank 1a measuring unit 1b inflow line 1c discharge line 1d communication line 1e corner 2 impeller 2a motor 2b impeller shaft 3 low noise ring 4 guide vane 5 stator

Claims (1)

[Claims] 1. A circulating water tank for forcibly circulating water in a water tank with an impeller to generate a water flow in a fixed direction in the measurement unit and to measure a sound caused by an object placed in the water flow in the measurement unit. A circulating water tank having a low-noise ring, wherein a low-noise ring having a radius smaller than the impeller is provided concentrically close to the impeller upstream.