JPH0735091A - Device for preventing swirl in delivery pipe of centrifugal turbo machinery - Google Patents

Abstract

PURPOSE:To enhance the performance of a centrifugal compressor by straightening a pressurized fluid inside a delivery pipe that is delivered from the centrifugal turbo machinery, thus preventing swirl. CONSTITUTION:An inward straightening vane 21 for regulating the swirl of compressed air is provided on the inner peripheral surface of a delivery pipe 2 connected to the swirl-chamber outlet of centrifugal turbo machinery, to constitute a device for preventing swirl in the delivery pipe of the centrifugal compressor. The straightening vane 21 may be provided to partition the inside of the delivery pipe 2 radially.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an eddy current preventive device for a centrifugal turbomachine which regulates an eddy current of a fluid by providing a straightening plate in a discharge pipe of a turbomachine such as a centrifugal compressor or a centrifugal pump.

[0002]

2. Description of the Related Art Conventionally, for example, a centrifugal chamber type centrifugal compressor has been widely used for turbochargers of industrial and automobile engines, and this type of centrifugal compressor is a turbine blade or an electric motor utilizing exhaust air of the engine. It is installed so that the impeller provided coaxially using a drive source such as the above can be rotated at high speed in the casing.

[0003]

However, in a turbomachine such as a centrifugal compressor having a swirl chamber, a swirling flow is generally generated in the swirl chamber (see FIG. 4), and the loss caused by this swirling causes the swirling flow to exceed the design point. The total pressure rise and the maximum flow rate achieved in the large flow range are reduced. In addition, in the conventional centrifugal compressor, at low flow rate during low speed rotation or sudden overload, unsteady phenomena such as rotating stall peculiar to turbomachinery and surging due to pulsation occur, and the centrifugal compressor is Since severe abnormal vibration is generated in the pipeline system including it and stable operation becomes impossible, operation in this area must be avoided and there is a problem that operation in the low flow rate area is restricted. On the other hand, various attempts have been made to improve the shape of the impeller and the spiral chamber of the conventional centrifugal compressor to improve the efficiency, but the total pressure rise over the entire operating range, the maximum flow rate increase, and the surging in the low flow rate region have been attempted. It did not reach the limit.

Therefore, in the present invention, the performance characteristics of the centrifugal compressor and the discharge pipe connecting the centrifugal compressor and the working equipment installed downstream are grasped by an experimental apparatus, and the vortex flow of the fluid compressed in the discharge pipe is grasped. By providing a straightening plate that regulates the above, it is possible to eliminate the above-mentioned conventional problems, enable more effective operation in the entire flow rate range, and improve the performance of a centrifugal turbomachine that can be manufactured at low cost. It is intended to provide an eddy current prevention device.

[0005]

In order to achieve the above object, a vortex flow preventer for a discharge pipe in a centrifugal turbomachine according to the present invention is a discharge pipe 2 connected to an outlet of a spiral chamber 8 of a centrifugal turbomachine 3. On the inner peripheral surface side, inward rectifying plates 21, 22 and 23 for restricting the vortex flow of the compressed fluid are provided. A straightening plate 2 that radially divides the inside of the discharge pipe 2 is provided.
It is also possible to provide 1.

[0006]

The vortex flow preventer for the discharge pipe in the centrifugal turbomachine constructed as described above is provided with a rectifying plate 21 provided in the discharge pipe 2 with a vortex-like fluid sent out while being swirled from the centrifugal turbomachine 3. 22 and 23 are guided so as to be regulated and rectified, and are delivered in a state where eddy currents are prevented. As a result, the internal loss of fluid such as compressed air can be reduced, energy efficiency can be increased, and the surging limit can be set to the lower flow rate side.

[0007]

Embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 is an experimental apparatus for confirming the performance characteristics of the centrifugal turbomachine 3, and the experimental apparatus 1 has a metering valve 6 in a discharge pipe 2 connected to a discharge port 3b of the centrifugal turbomachine 3. Turbine blade 4a that is connected to the discharge pipe 7 and that rotates coaxially with the impeller 3a of the centrifugal turbomachine 3.
An air supply adjusting device 5 to be described later is provided on the suction port 4b side of the turbine 4 in which is installed.

The centrifugal turbomachine 3 used in the experimental apparatus 1 is a turbocharger for an automobile, and is shown in FIGS.
As shown in Fig. 4, the impeller 3a is rotated in the casing 8b that forms the spiral chamber 8 that is continuous with the diffuser 8a, so that the outside air is sucked from the suction pipe 9 connected to the suction port 8c and is pressurized in the spiral chamber 8. The compressed air W is discharged from the discharge port 3b to the discharge pipe 2.

As shown in FIGS. 6 (a) and 6 (b), the discharge pipe 2 has flanges 2a fixed on both sides thereof and a discharge port 3 formed therein.
b and a flange provided at the end of the discharge pipe for measurement 7 are interposed and fastened with a bolt 2b so as to be detachable and replaceable. At each measurement point of the centrifugal turbomachine 3 and the discharge pipe 2, a pressure detector (measurement discharge pipe) A, a pitot pipe P, an anemometer H,
A thermometer T and the like are attached, and the data detected by these sensors are displayed on a monitor device (not shown).

The air supply adjusting device 5 connects the surge tank 10 with a roots-type blower 12 driven by an electric motor 11 via a safety valve 13 through a pipe line 10a, and the surge tank 10 has flow control valves 14, 14a. , 14b are provided, the flow control valve 14 side is connected to the suction port 4b of the turbine 4, and the compressed air in the surge tank 10 is regulated by the flow control valve 14 so that the turbine impeller can be controlled. 4a is rotated, and the impeller 3a of the centrifugal turbomachine 3 provided coaxially can be set and adjusted to an arbitrary rotation speed.

Next, by using the experimental apparatus 1 configured as described above, a hollow cylindrical discharge pipe 2 similar to the conventional one shown in FIG.
An example of an experiment in which the centrifugal turbomachine 3 is mounted will be described. Drive the electric motor 11 and blower 12 to surge tank 1
After storing the compressed air in 0, the flow rate control valve 14 is opened so that the impeller 3a makes a predetermined rotation (in this experiment, the rotation of the impeller 3a is set to 10,000 rpm which is a general-purpose rotation range). As a result, the centrifugal turbomachine 3 has the impeller 3a.
2 rotates in the direction of the arrow in FIG. 2, sucks the outside air from the suction port 8c, compresses it in the spiral chamber 8 while guiding it by the diffuser 8a, and sends the compressed air W from the discharge port 3b to the discharge pipe 2 side.

At this time, the opening of the throttle valve 6 provided at the rear end of the measuring discharge pipe 7 is adjusted to adjust the load on the centrifugal turbomachine 3, and the impeller outlet radius with respect to the peripheral speed U2 of the impeller 3a. Flow coefficient Φ = calculated from the ratio of wind velocity C2r
Change C2r / U2. Then, every time the flow coefficient Φ changes, the total pressure Pt generated in the discharge pipe 2 detected by the pressure detector A mounted on the discharge pipe 2 is measured, and obtained from the ratio of the total pressure Pt and the atmospheric pressure Pa. Fig. 7 shows the total pressure ratio Pt / Pa
As shown in, the horizontal axis is the flow coefficient Φ and the vertical axis is the total pressure ratio P.
Characteristic curve a is obtained by plotting t / Pa on a graph.
was gotten.

According to this, the maximum total pressure ratio Pt / Pa increases from 1.032 to 1.035 with the flow coefficient Φ = 0.10, and the maximum flow range also increases from 0.17 to 0.18. There is. Further, the surging limit (minimum operable flow rate) is such that the flow coefficient Φ is around 0.06, and the total pressure ratio Pt / Pa at this time is about 1.034. If the flow coefficient is less than Φ, abnormal vibration occurs in the centrifugal turbomachine 3 and the pipe system, and the practical operation cannot be performed. Further, it was possible to understand that the compressed air W in the swirl chamber 8 was flowing as shown in FIG. 4 by the sensors provided in the casing 8b and provided in the swirl chamber 8. That is, the white arrow indicates the impeller 3
It is the flow of the compressed air W immediately after being discharged from a, and the black arrow indicates that it is compressed by the rotation of the impeller 3a and is sent out from the discharge port 3b. The compressed compressed air W1 is then sent out.

In order to confirm the flow of the compressed air W in the discharge pipe 2, the discharge pipe 2 was replaced with a transparent hollow cylinder, and oil paint was injected from two points on the windward side. As shown in FIG. 5, the oil paint is drawn by the flow of the compressed air W in a spiral shape on the inner surface of the discharge pipe 2 as a curve K of two lines, and the compressed air W swirls in the discharge pipe 2 while swirling. It could be visualized to be delivered.

Therefore, the discharge pipe 2 has the passage 2c in the discharge pipe 2 as shown in FIG. 6 (e) (excluding the phantom line), and the round bar 2d is interposed in the central portion of the discharge pipe 2 as described above. When the total pressure was measured for each flow coefficient Φ by the same method as the experiment, the characteristic curve b shown in FIG. 7 was obtained. According to this, the total pressure ratio Pt
The maximum value of / Pa is slightly higher than the maximum value of the characteristic curve a due to the cylindrical discharge pipe 2 described above and the efficiency at this point is improved, but the flow coefficient Φ at the surging limit is a small value of 0.08 and is practical. Has been shown to be insufficient. The total pressure ratio Pt / Pa in the vicinity of the flow coefficient Φ0.17 depending on the fully open level of the throttle valve 6 is substantially the same in the above two examples.

From the above-mentioned experiment, the discharge pipe 2 which is a cylindrical pipe with a round rod inside has a round rod 2d in the cylinder, so that although the total pressure in the passage 2c increases, the swirling of the compressed air W is promoted and it becomes a vortex. It is estimated that there is a lot of internal loss of energy. Further, the flow of the compressed air W in the discharge pipe 2 according to the above experimental example swirls as described above, and the axial flow velocity decreases due to the decrease in the flow rate, so that the effect of swirling greatly contributes to the performance characteristics in the low flow rate region. . In the large flow rate region, the axial velocity is large, and the absolute velocity, which is a combination of the swirl and the axial velocity, increases, and in general, it is considered that friction loss proportional to approximately the square of the absolute velocity occurs and the performance characteristics are deteriorated. .

Therefore, from the discharge port 3b of the spiral chamber 8 to the discharge pipe 2
By providing the rectifying device for preventing the swirling flow of the compressed air W, it is possible to solve the problems and improve the performance thereof without adding any special action to the complicated and expensive centrifugal turbomachine 3. Therefore, as shown in FIGS. 6A and 6B, the inward flow straightening plate 21 that restricts the vortex flow of the compressed air to the inner peripheral surface side of the discharge pipe 2 is a cross shape (radial shape) inside.
The performance characteristic curve c shown in FIG. 7 was obtained by performing a test in the same manner as described above by replacing the discharge pipe 2 with the discharge pipe 2 described above. According to this, the surging limit in the low flow rate region is around 0.04, which can be greatly improved from the conventional performance characteristic curve a to the low flow rate region, and the maximum total pressure ratio Pt / Pa from the maximum flow region is around 1.037. It has been confirmed that the total pressure ratio Pt / Pa rises substantially evenly in the entire flow rate range up to and the overall efficiency is remarkably increased.

In order to reconfirm the effect of the current plate, another turbocharger was attached to the apparatus shown in FIG. 1 and the characteristics of the centrifugal compressor were determined. As shown in FIG. Similar results were obtained. However, a ', b'
(Both 50,000 rpm) and a ″, b ″ (both 4
(10,000 rpm) corresponds to the circular pipe a and the cross pipe c in FIG. 7.

Therefore, it has become possible to greatly increase the operating range of the centrifugal turbomachine 3 toward the large flow rate side and further increase the total pressure rise. Although the performance characteristics are slightly degraded on the low flow rate side, the surging start point, which is the most important unsolved problem in this type of turbo compressor, can be shifted to a lower flow rate range. Therefore, the centrifugal turbomachine 3 having the conventional swirl chamber 8 can greatly expand the operating flow rate range and operate with high performance.

As another embodiment in which the discharge pipe 2 is provided with an inward rectifying plate 21 for restricting the vortex flow of the compressed air W, FIG.
As shown in (c), the discharge pipe 2 is provided with four straightening vanes 22 protruding toward the inner surface of the discharge pipe 2 on the inner peripheral surface side of the discharge pipe 2, and the discharge pipe as shown in FIG. It is also possible to obtain a discharge pipe 2 having a rectifying plate 23 that divides the inside of 2 into two chambers along the normal line of the cross section, and these mechanisms also have the same effect as the curve c in the discharge pipe 2 described above. It can be easily inferred that it will be done. Further, the flow straightening plates 21, 22, and 23 are bent in a spiral shape opposite to the fluid swirling direction, and the discharge pipe 2 is provided.
It may be provided in the longitudinal direction of the inside of FIG. 6 (e).
A straightening plate may be installed in the round bar 2d as shown in phantom.

When the discharge pipe 2 with the current plate 21 confirmed by the above-mentioned experiment is used in the centrifugal turbomachine 3 of the turbocharger of the automobile engine, the combustion efficiency of the engine can be improved and the generated heat can be increased. Energy can be increased and the engine can be made highly efficient and compact. Further, since the surging limit can be set to a lower flow rate range, it is possible to suppress the occurrence of abnormal vibration of the centrifugal turbomachine 3 and the pipeline system at the time of low speed rotation of the engine, and it is possible to manufacture the related parts and members of the engine with a simple structure. At the same time, it is possible to reduce the weight. In addition, although the above-mentioned embodiment explained the centrifugal compressor of the engine for automobiles, the eddy current prevention device according to the present invention is not limited to the case of the above-mentioned embodiment, and includes a pump or the like for a fluid other than air, It is applied to all centrifugal turbomachines in which a vortex is generated on the discharge pipe side.

[0022]

Since the present invention is constructed as described above, it has the following effects. (1) The pressurized fluid delivered from the centrifugal turbomachine is delivered in a state in which it is rectified by a rectifying plate provided in the discharge pipe and vortex flow is prevented, so internal loss of the fluid is reduced and energy efficiency is reduced. Can be increased. (2) Further, since the surging limit can be improved to a lower flow rate region, abnormal vibrations of the downstream turbomachines and engines such as engines can be suppressed, the operation can be performed quietly and smoothly, and each related component or member. It is possible to provide a low-cost actuating device and a centrifugal turbomachine that can be reduced in size and weight.

[Brief description of drawings]

FIG. 1 is a plan view showing an experimental device of a centrifugal compressor.

FIG. 2 is a side view showing a centrifugal compressor partially broken away.

3 is a sectional view taken along the line AA of FIG.

FIG. 4 is a schematic diagram showing a flow of compressed air in a centrifugal compressor.

FIG. 5 is a recording diagram of oil paint in a transparent discharge pipe.

FIG. 6A is a front sectional view of a discharge pipe according to an embodiment of the present invention. (B) is the side view. FIG. 7C is a side sectional view of the discharge pipe according to the second embodiment. FIG. 6D is a side sectional view of the discharge pipe according to the third embodiment. (E) is a side sectional view in which a round bar is inserted into a hollow cylindrical discharge pipe.

7 is a graph showing performance characteristic curves of a centrifugal compressor using various discharge pipes by the experimental apparatus of FIG.

FIG. 8 is a graph showing a performance characteristic curve of an experiment using another centrifugal compressor.

[Explanation of symbols]

 1 Experimental Device 2 Discharge Pipe 3 Centrifugal Turbomachine 3a Impeller 3b Discharge Port 4 Turbine 5 Air Supply Control Device 6 Throttle Valve 8 Whirlpool Chamber 8c Suction Port 9 Suction Pipe 21, 22, 23 Rectifier Plate W Compressed Air

Claims (2)

[Claims] 1. A swirl chamber (8) of a centrifugal turbomachine (3)
On the inner peripheral surface side of the discharge pipe (2) connected to the outlet, the inward flow straightening plates (21), (22), (2) that restrict the vortex flow of the fluid.
3) is provided, a device for preventing vortex flow of a discharge pipe in a centrifugal turbomachine. 2. A vortex flow preventer for a discharge pipe in a centrifugal turbomachine according to claim 1, wherein the discharge pipe (2) is provided with a straightening plate (21) for radially partitioning the inside thereof.