JPH0842494A - Fluid machine with variable guide vane - Google Patents

Abstract

PURPOSE:To enable a fluid machine to be operated in a wide flow range by avoiding any unstable phenomenon generated at operating the fluid machine in the flow range except the design point flow. CONSTITUTION:In a fluid machine provided with diffuser vanes 4, it is provided with an input device 3 for inputting the required operating condition of the fluid machine, a pressure detecting device for detecting the pressure on the diffuser vane pressure face side on the disc having the diffuser vanes 4, fitted thereon, pressure on the negative pressure face side, and pressure on the other inlet side position, a computation processing device U for computing the operating condition of the fluid machine so as to exhibit the required performance input by the input device, consequently deciding the direction of flow from an impeller 8 based on the pressure detected by the pressure detecting device so as to decide the angle of the diffuser vane, and a first control drive device 5 for driving and controlling the diffuser vane into its decided angle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid machine such as a centrifugal and mixed flow type liquid pump, a blower for gas and a compressor, and more particularly to a fluid machine with an inlet guide vane and a diffuser vane. In the present specification, the above fluid machines are generically called pumps.

[0002]

2. Description of the Related Art Conventionally, when centrifugal and mixed flow pumps are operated in a flow rate range other than the design point, flow separation occurs in each constituent element such as an impeller and a diffuser. There is a drawback that the efficiency of the pump is lower than that of the design point flow rate. In order to solve this, a method has been adopted in which a variable inlet guide vane or a diffuser vane is attached to a pump, and this is operated by moving the vane so as to match the flow.

As a typical example thereof, Japanese Patent Publication No. 4-18
No. 158, Japanese Examined Patent Publication No. 4-18159, JP-A-63-23
9398, JP-A-63-230999, JP-A-55
-107097 and the like.

By the way, in order to optimally control the diffuser blades so as to match the operating state of the pump, it is necessary to accurately grasp the flow out of the impeller in advance. Furthermore, in a pump with inlet guide vanes, if the angle of the inlet guide vanes is changed, the flow out of the impeller will change for each angle of the guide vanes, so the performance of the pump will be different for each angle of the inlet guide vanes. You need to know in advance.

In the conventional technique as described above, it is necessary to determine the diffuser vane angle for each angle of the inlet guide vane and conduct the test, and to control the guide vane based on this data. There is a drawback that it becomes complicated, and the apparatus and control software are very expensive.
Further, there are many drawbacks such that it takes time to automatically select the optimum value in order to operate the pump at the most suitable guide vane angle by incorporating the pump into the device.

As a method for calculating the flow angle at the outlet of the impeller, there is Japanese Patent Laid-Open No. 4-81598. However, in this method, some assumptions are made in the method for calculating the flow angle, and in general, the flow at the outlet of the impeller is Since it is distorted, it is impossible to calculate the flow angle from the static pressure of the wall surface, and in the region where the flow becomes unstable, there are many drawbacks such as accuracy problems.

Further, pressure holes are provided in the diffuser blades,
Japanese Patent Laid-Open No. 57-56699 discloses a method for measuring the pressure and calculating the flow direction outflowing from the impeller, but this method cannot be adopted for a diffuser blade having a small blade thickness, and is also processed. There were many drawbacks such as the above cost.

As a method of measuring the wall surface pressure on the pressure surface side and the negative pressure surface side of the diffuser blade, Japanese Patent Laid-Open No. 62-5179.
Although there is No. 4, when the diffuser blade is rotated because there is a pressure hole in the wall of the diffuser, the relative position of the pressure hole changes depending on the angle, and in some cases the pressure hole is hidden behind the diffuser blade. However, there was a drawback that measurement became impossible.

Further, if the angle of the inlet guide vanes or diffuser vanes is changed, the characteristics of the pump will change drastically. Therefore, unless a means for grasping the angle of the flow flowing out from the impeller is used, each guide vane A method has been taken in which a performance test is carried out in advance for each angle, and the angles of the inlet guide vanes and diffuser vanes are determined based on the test results.

Further, when the pump operation is automatically controlled by using this method, the angles of the inlet guide vanes and diffuser vanes are changed at least three times (Japanese Patent Publication No. 4-1815).
No. 8 and Japanese Examined Patent Publication No. 4-18159) Since it is necessary to take a method to determine the angles of the inlet guide vanes and diffuser vanes by grasping the operating state of the pump at that time, it takes a long time to set, especially There were many problems at the driving point where the state must be determined instantaneously, such as driving near the surging point.

Further, in the control in which the number of revolutions is changed, these controls become more difficult, and the control device becomes high-grade.
There is a drawback that the cost of the device and the cost of the control software are high.

As a method for determining a blade angle by providing a pressure hole on the diffuser blade and measuring the pressure,
No. 7-56699 exists, but the flow out of the impeller greatly changes in the width direction depending on the operating state of the pump. Therefore, if it is measured only near the center of the diffuser blade, the flow angle error is large. .

Further, since there is a pressure hole on the surface of the diffuser blade, the total pressure of the flow may be measured. In the case of handling a high-speed flow, the pressure level becomes larger than the static pressure, and the pressure detecting device is used. It is necessary to use an excessively large measurement range, which causes a problem in measurement accuracy. Further, this method cannot be adopted for diffuser blades having a thin blade, and there is a problem in that the cost is high.

The present invention has been made in view of the above circumstances, and is capable of operating a fluid machine in a wide flow rate range while avoiding an unstable phenomenon that occurs when the fluid machine is operated in a flow rate area other than the design point flow rate. An object of the present invention is to provide a fluid machine with guide vanes.

[0015]

FIG. 1 is a schematic view showing the state of the outlet of the impeller 8 for explaining the concept leading to the present invention. The flow directions of the fluid flowing out from the impeller 8 are indicated by arrows of a (design flow rate), b (small flow rate), and c (large flow rate). As is clear from this figure, at flow rates other than the design point, the angle of attack of the flow on the pressure surface side of the diffuser blade 4 at a large flow rate and the flow angle on the suction surface side of the diffuser blade 4 at a small flow rate become excessive, and the flow is separated. Will end up. As a result, the loss in the diffuser increases as shown in the relationship between the dimensionless suction flow rate and the dimensionless diffuser loss in FIG. As a result, the overall performance of the pump is
As shown in (b) as the relationship between the dimensionless suction flow rate and the pump efficiency, the efficiency decreases on the small flow rate side and the large flow rate side from the design point.

In order to solve this, when the diffuser vanes are made variable and the flow rate deviates from the design flow rate, the diffuser vanes can be moved by moving the diffuser vanes so as to match the impeller outlet flow (flows b and c in FIG. 1). Can be made as shown by the broken line in FIG. As a result, the overall performance of the compressor can be set as shown by the broken line in FIG. 2B, and highly efficient operation can be performed in a wide flow rate range.

The present invention has been made on the basis of the above consideration, and the invention according to claim 1 is a fluid machine equipped with diffuser blades, wherein the pressure surface side and the suction surface side of the diffuser blade and the diffuser portion. Pressure detecting device for detecting the pressure at a predetermined position, an arithmetic processing device for determining the angle of the diffuser blade based on the pressure detected by the pressure detecting device, and drive control of the diffuser blade to the determined angle. A fluid machine with variable guide vanes, comprising: a first control drive device.

The invention according to claim 2 is further provided with an input device for inputting a required operating state of the fluid machine, and the arithmetic processing device is capable of exhibiting the required performance input by the input device. The fluid machine with variable guide vanes according to claim 1, wherein the operating state of the fluid machine is calculated. The invention according to claim 3 is the fluid machine with variable guide vanes according to claim 1 or 2, wherein the pressure detecting device is provided on a board to which the diffuser vanes are attached. . The invention according to claim 4 further comprises: an inlet guide vane; and a second control drive device for driving and controlling the inlet guide vane to an angle calculated based on a predetermined arithmetic expression. The fluid machine with variable guide vanes according to any one of claims 1 to 3. The invention according to claim 5 further comprises a third control drive device for controlling the rotational speed of the fluid machine, wherein the fluid machine with variable guide vanes according to any one of claims 1 to 4 is provided. is there.

The inventors also conducted an experiment in which a pressure sensor was attached to each of the suction pipe, the diffuser and the discharge pipe of the pump to change the flow rate of the compressor. FIG.
(A) shows the waveform signal of the output of the above sensor, the left side shows the pressure fluctuation measured at two positions in the circumferential direction of the diffuser, and the right side shows the measurement result of the pressure fluctuation measured at the suction pipe and the discharge pipe. It is a thing. As is clear from this figure, when the flow rate is less than the design point flow rate, the fluctuation value of the pressure in the diffuser becomes large first (left figure), and when the flow rate is further decreased, the fluctuation in the pipe becomes large (right side). (Fig.), It can be seen that surging occurs.

FIG. 3 (b) is a diagram showing the relationship between the dimensionless flow rate based on the design flow rate and the dimensionless head coefficient obtained by making the head of the compressor dimensionless based on the head at the design flow rate. In FIG. 3 (b), and are respectively shown in FIG.
It corresponds to the three flow rates of (a). Therefore, by quantitatively grasping such a change in the state quantity, it is possible to perform stable operation while avoiding the occurrence of surging based on an appropriate threshold value.

The invention according to claim 6 is based on such consideration, and in a fluid machine equipped with a diffuser blade, a pressure for detecting at least the pressure surface side and the suction surface side pressure of the diffuser blade. A detector and a reference flow rate are set, and at a flow rate higher than this reference flow rate, the direction of the flow out of the impeller is determined based on the pressure detected by the pressure detection apparatus to control the angle of the diffuser blade. However, at the reference flow rate or less, calculate the fluctuation value of the pressure value detected by the pressure detection device,
A fluid machine with variable guide vanes, comprising: a control device for controlling a diffuser angle so that the variation value is equal to or less than a predetermined threshold value.

[0022]

In the invention described in claim 1, the pressure detecting device detects the pressure at the pressure surface side and the negative pressure surface side of the diffuser blade and at a predetermined position of the diffuser portion, and the arithmetic processing device is the pressure detecting device. The angle of the diffuser vane is determined based on the detected pressure, and the first control drive device drives and controls the diffuser vane at the determined angle to directly output a pressure signal from a position sensitive to surging. And the diffuser vane angle is controlled based on this, and as a result, the fluid machine with variable guide vanes operates stably.

In a sixth aspect of the present invention, the controller determines the direction of the flow out of the impeller based on the pressure detected by the pressure detection device at a flow rate higher than the reference flow rate. The blade angle is controlled, and when the flow rate is equal to or lower than the reference flow rate, the fluctuation value of the pressure value detected by the pressure detection device is calculated, and the diffuser angle is controlled so that the fluctuation value is equal to or lower than a predetermined threshold value. Therefore, appropriate control is performed in each flow rate range according to the characteristics of the fluid machine.

If there is an inlet guide vane, a processor is used to calculate the angle of the inlet guide vane based on an arithmetic expression, and the second control drive unit automatically controls the inlet guide vane. The rotation speed of the fluid machine is controlled by the third control drive device. When both the diffuser vane and the inlet guide vane are present, the rotation speeds of both the diffuser vane and the inlet guide vane and the third control drive unit are automatically adjusted by the above method by the first and second control drive units. So that it can be operated by controlling it dynamically.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a fluid machine with variable guide vanes according to the present invention will be described below with reference to FIGS.

4 and 5 are views showing a single-stage centrifugal compressor to which the present invention is applied, FIG. 4 is a longitudinal sectional view thereof, and FIG. 5 is a partial side view thereof. As shown in these figures,
The diffuser vane 4 is connected via a plurality of gears 11 to an actuator 12 forming a part of the first control drive device, and the vane angle is variable. Also, the entrance guide blade 6
Is connected to an actuator 14 forming a part of the second control drive device via a plurality of gears 13, and the blade angle is variable.

FIG. 6 is a block diagram for explaining the control mechanism of the fluid machine with variable guide vanes according to the present invention. As shown in FIG. 6, in the pump with variable guide vanes, an arithmetic processing unit U including an arithmetic unit 1 and a storage unit 2, an input device 3 capable of inputting a required operating state of the pump, and a diffuser vane 4 are variable. It is provided with a controllable first control drive device 5, a second control drive device 7 capable of variably controlling the inlet guide vanes 6, and a third control drive device 9 capable of controlling the rotation speed of the impeller 8, that is, the rotation speed of the pump. .

7 (a) and 7 (b) are front views and FIG. 7 (b) is a sectional view, respectively. These holes may be on one board or one on another board. As shown in FIG. 7, the disc 1 to which the diffuser vane 4 is attached
0 is provided with a pressure hole 11. Reference numeral 11-1 is a pressure detecting pressure hole on the diffuser blade pressure surface, 11-2 is a pressure detecting pressure hole on the diffuser blade negative pressure surface, and 11-3 is a reference pressure detecting pressure hole provided on the inlet side. A pressure detector is provided in each of the three pressure holes, so that the pressure at each position is detected.

The output of the pressure detector is input to the arithmetic processing unit U of the control mechanism as shown in FIG. 6, where the dynamic pressure ΔPd of the flow is calculated by the pressure of the pressure hole 11-3. The arithmetic processing unit U further calculates the pressure difference (P ₁ -P ₂ ) between the pressure hole 11-1 and the pressure hole 11-2, and the calculated pressure difference ΔP
The ratio of d, ξ = (P ₁ −P ₂ ) / ΔPd, is obtained, and the blade angle of the diffuser is calculated from this value. This is done, for example, according to the graph shown in FIG. This figure summarizes the data obtained by the inventor using the compressor, and the horizontal axis is
The dimensionless flow rate in which the flow rate at each operating point is made dimensionless by the flow rate at the design point, and the vertical axis indicates the angle of the diffuser blade according to the present invention.

In FIG. 8, when the dimensionless flow rate is larger than 0.6, the dynamic pressure ΔPd of the flow is calculated by the pressure in 11-3 shown in FIG. 7, and the pressure holes 11-1 and 1-1 are calculated.
Ratio with pressure difference (P ₁ −P ₂ ) in 1-2 ξ = (P ₁
−P ₂ ) / ΔPd is obtained, the blade angle of the diffuser is calculated from this value by the arithmetic processing unit U, and the blade angle determined by variably controlling the diffuser blade 4 by the first drive unit 5 is shown.

The dynamic pressure ΔPd is obtained as follows. The radial velocity component Cm _{2 at the} impeller exit is P _r
The pressure P _i of the impeller inlet and the ratio of the pressure P ₃ in the pressure hole _{11-3 (Pr = P 3 / P} i), the suction flow Q, When the blockage of the impeller outlet B, Cm ₂ = (1 / P _r ) ^{(1 / k)} Q / (πD ₂ b ₂ B) Cu ₂ = σU ₂ −Cm ₂ cotβ, where Cu ₂ is the slip coefficient of the impeller, U _{2 is} the peripheral speed of the impeller, and β ₂ is the blade angle at the exit of the impeller. Expressed as ₂ . Therefore, the absolute velocity C at the impeller outlet is expressed as C ² = Cm ₂ ² + Cu ₂ ² . The density ρ _{2 at the} impeller outlet is expressed as ρ ₂ = ρ ₁ (P _r ) ^{(1 / k)} , where ρ ₁ is the density at the impeller inlet. Therefore, the dynamic pressure ΔPd at the impeller outlet is ΔPd = It can be obtained from C ² / 2ρ ₂ . Therefore, ξ is obtained from ξ = (P ₁ −P ₂ ) / ΔPd.

The value of ξ with respect to the flow angle is obtained in advance by a verification wind tunnel. FIG. 9 shows an example thereof, in which the horizontal axis indicates the blade angle with respect to the flow and the vertical axis indicates 11-1 and 11 at the time of verification.
The ratio between the -2 differential pressure and the dynamic pressure ΔPd (this is obtained by measuring the difference between the total flow pressure Pt and the static pressure Ps. This is a general method different from the above method). The value of ξ obtained from By storing this curve in a storage device, the angle of the flow with respect to the blade can be obtained from ξ at the compressor outlet obtained by the above method. On the other hand, the flow angle α at the outlet of the impeller is obtained from α = arctan (Cm ₂ / Cu ₂ ), so if the difference between the two is calculated, the deviation angle from the flow angle of the diffuser blade can be obtained. it can. If the angle of the diffuser blade is corrected by this deviation angle, the angle of the diffuser blade can be matched with the flow flowing out from the impeller. If you cannot match at once, you can repeat this step several times to get a perfect match.

Further, in FIG. 8, the dimensionless flow rate is 0.6.
In a smaller flow rate range, the pressure hole 11-3 shown in FIG. 7 is connected to a fluctuating pressure measuring device to obtain a fluctuating value Fp of the amplitude for each minute time, and compare this with a threshold value Fp ^*. Shows the blade angle determined by variably controlling the diffuser blade 4 by the first drive device 5 so that the variation value of the amplitude for each minute time becomes equal to or less than the threshold value. How to obtain the variation value Fp will be described with reference to FIG. In this figure, T is a minute time for calculating the fluctuation value once,
δt is the pressure value P _i (Q, t) that is the basis for calculating the fluctuation value
Is the sampling pitch of. The fluctuation values Fp and Fp ^* are
It is the standard deviation per unit time of the state quantity measured at the pitch of δt during the time T and is given by the following equation. Fp (Q) = [1 / TΣ {Pi (Q, t) −Mi
(Q)} ² ] ^1/2 However, Mi (Q) = 1 / TΣPi (Q, t) Both so-called DC data having a constant bias and AC data not having such a bias can be handled by the above equation.

The measurement time T needs to be a short time so that the index value of the variation of the state quantity can be accurately calculated and a quick response can be taken. In this embodiment, 60 / ZN (second) is used as a standard for setting such time T. Here, N is the number of rotations of the impeller 8 (times / minute), and Z
Is the number Z of blades of the impeller 8, and therefore 60 / ZN
Is a cycle of fluctuations in state quantities such as pressure that are essentially generated by the rotation of the impeller 8. T needs to be set large enough not to be affected by such an essential variation, and therefore the following conditions are imposed. T ≧ K ₁ · 60 / ZN Therefore, in practice, T should be set to this lower limit value.
Here, K ₁ is a constant determined by the fluid machine, and when the machine is tested, or if it is a mass-produced product, the performance of its representative product is checked in advance and set by the constant input device 3.

Next, a method of setting the sampling pitch δt will be described. Such a sampling period δ
From the viewpoint of calculating an accurate index value, t is preferably as small as possible. However, it is rather undesirable that the computer is overloaded due to excessive sampling and the calculation takes time. In this embodiment, 60 / ZN (seconds) is also used as a standard for setting such time δt. That is, it is necessary to set δt small enough not to be affected by the fluctuation of the state quantity such as the pressure that is essentially generated by the rotation of the impeller 2. Therefore, the following conditions are imposed. δt ≦ K ・ 60 / ZN

Further, in this embodiment, as described with reference to FIG. 3, the setting is changed in view of the fact that the amplitude period is different between the design point and the case where the operation becomes unstable at a lower flow rate. I am trying. That is, the sampling period δt for detecting an unstable region in which the head rises to the right is K ₂ · 60 / ZN, and the sampling period δt for detecting the surging phenomenon is K ₃ · 60 / ZN. . Where K ₂ and K ₃
Is a constant determined by the fluid machine, and similarly to the case of K ₁ , the performance of the representative machine is examined in advance during the test of the machine or in the case of a mass-produced product, and is set by the input device 3.

The fluctuation value during the operation of the fluid machine is calculated as described above each time, and the method for obtaining the fluctuation value (threshold value γ) as a criterion for determining the occurrence of surging will be shown below. FIG.
1 is the data obtained by the research of the present inventor, the horizontal axis is a dimensionless flow rate in which the flow rate at each operating point is made dimensionless by the flow rate at the design point, and the vertical axis is the fluctuation value of the pressure at the design point. Value (= F
p ^* ) indicates a dimensionless variation value. The circles in the figure indicate those obtained from the measurement results of the pressure on the diffuser wall surface. The conditions here are as follows. N = 9000 rpm, Z = 17 K ₁ = 2000, K ₂ = 5, K ₃ = 20

From this result, it is understood that the dimensionless fluctuation value 8 increases from the flow rate region where the dimensionless flow rate is smaller than 0.6. Here, a limit value with which the pump can be operated stably can be set appropriately and used as a threshold value. In this example, F
It is determined that 1.5 is the limit for p / Fp ^* , and 1.5Fp ^* is used as the threshold γ. Next, by rotating the diffuser vanes so that this value becomes equal to or less than the threshold value shown in this graph at each flow rate, the relationship in the region of the dimensionless flow rate of 0.6 or less shown in FIG. 8 is obtained. To be From this figure, it can be seen that the diffuser vane angle changes in proportion to the flow rate when the dimensionless flow rate is smaller than 0.6. By calculating this, the suction flow rate of the pump, and the head rise by the arithmetic processing unit U, and further variably controlling the diffuser blade 4 by the first control drive unit 5, the diffuser blade 4 can be optimally controlled.

Furthermore, the present inventors also devised a method of setting the inlet guide vanes so as to exhibit the required performance of the pump. FIG. 12 shows a flowchart in that case. First,
In the case of a fluid machine whose rotation speed can be changed, an appropriate rotation speed is set in advance. In step 1, the requested flow rate Q and head H are input, and in step 2, the flow rate coefficient φ and the pressure coefficient ψ are calculated. Next, in step 3, the flow coefficient φ,
The quadratic curve coefficient passing through the pressure coefficient ψ is calculated, and the intersection points φ ′, ψ ′ with the characteristics when the inlet guide vane is 0 degrees are calculated in step 4, and the angle of the inlet guide vane is calculated from the following equation in step 5. Calculate (k is a constant). α = arctan (k (φ′−φ) / φ ′) Next, in step 6, the inlet guide vane angle control is performed, and in step 7, it is determined whether or not α is 0 (fully open). If it is not 0, the head and flow rate are measured in step 9 to obtain φ ″,
ψ ″ is calculated. Next, in step 10, it is determined whether or not the head H is an appropriate value, and if it is an appropriate value, the control ends, and if it is not an appropriate value, α ′ is calculated in step 11, and In step 12, (α-α ') is calculated, and then the process returns to step 6.

If α is 0 in step 6, such a request cannot be achieved if the number of rotations cannot be changed. Therefore, the process returns to step 1 and the setting is changed. If the number of revolutions can be changed, the number of revolutions is changed in step 8 and the process proceeds to step 9.

Next, the basis of the above equation will be described. FIG.
[Fig. 3] is an explanatory diagram of a characteristic curve and a resistance curve of the pump. As a first condition, the performance when the inlet guide vanes are 0 degrees is known. First, the flow rate Q of the optional requirement (given requirement)
From the head H, the flow coefficient φ (4 ・ Q / (π ・ D ₂ ²・
U ₂ )) and pressure coefficient ψ (g · H / (U ₂ ² )). This resistance curve is assumed to be a quadratic curve that passes through this arbitrary essential point (φ, ψ) and the origin (if there is a fixed resistance, the value is known and the intercept value of the ψ axis is determined). Find the coefficient of. Coordinates (φ ', ψ') of the intersection of this resistance curve and the characteristic curve when the known inlet guide vane is 0 degree
Is calculated by numerical calculation. From the coordinate value φ ′, the flow rate Q ′ is calculated by the following formula. When Q '= φ' · π · D a _{² 2} · U _2/4 impeller inlet area and A _1, it is obtained the impeller inlet axial velocity Cm ₁ from the following equation. Cm ₁ = Q '/ A ₁ = φ' ・ π ・ D ₂ ²・ U ₂ / (4 ・
A ₁ )

The head H'of the pump has a peripheral speed U of the impeller outlet.
_{From the difference} between the product U ₂ · Cu _{2 of 2} and the circumferential component Cu ₂ of the absolute velocity and the product U ₁ · Cu ₁ of the impeller inlet circumferential velocity U ₁ and the circumferential component Cu ₁ of the absolute velocity, Desired. H ′ = (U ₂ · Cu ₂ −U ₁ · Cu ₁ ) / g where ψ ′ = (g · H ′ / U ₂ ² ), then ψ ′ = (U ₂ · Cu ₂ −U ₁・ Cu ₁ ) / U ₂ ² . Since the angle of the inlet guide vanes is now 0 degree, the circumferential direction component C _U1 of the absolute velocity is 0. Therefore, the circumferential velocity component Cu ₂ of the absolute velocity at the impeller exit is obtained by the following equation. Cu ₂ = U ₂ · ψ ′ According to the research by the present inventor, it was found that the circumferential velocity component Cu ₂ of the absolute velocity at the impeller outlet depends only on the flow rate and does not change depending on the inlet guide vane angle. . Using this result, ψ of an arbitrary element (given element) is ψ = (U ₂ ² · φ′−U ₁ · Cu ₁ ) / U ₂ ² = φ′−U ₁ · Cu ₁ / U ₂ ² , the circumferential velocity component Cu ₁ of the absolute velocity at the impeller inlet is Cu ₁ = (φ′−φ) · U ₂ ² / U ₁ .

The angle of the inlet guide vane to satisfy any essential point is, when the root mean square diameter at the impeller inlet and _{D 1 rms, α 1 = arctan} (Cu 1 / Cm 1) = arctan (A 1 · ( ψ'-ψ) ・ U ₂ / (D ₂ ²・ φ '・
U ₁ )) = arctan (A ₁ · (ψ′−ψ) / (D ₂ · D ₁ rms ·
φ ′)) Here, when the constant k is k = A ₁ / (D ₂ · D ₁ rms), α ₁ = arctan (k (φ′−φ) / φ ′) can be obtained.

In this way, the arithmetic processing unit U calculates the angle of the inlet guide vanes 6 so that the required performance input by the input unit 3 can be exerted, and the second control drive unit 7 controls the inlet guide vanes 6 to operate. It became possible to operate by controlling automatically. Changing the angle of the inlet guide vanes 6 changes the flow condition in the impeller and therefore also the impeller exit flow condition. When there is the diffuser vane 4, the optimum angle for the flow can be calculated by the arithmetic processing unit.

Since this is the same even when the rotation speed of the pump changes, the rotation speed changes and the angle of the inlet guide blades changes, so that it is possible to operate the diffuser blade angle at the optimum state at any operating point. Become.

Depending on the angles of the inlet guide vanes 6 and the diffuser vanes 4, the flow rate and head specified by the input device 3 may not be satisfied. In that case, the second control drive device 7 moves the inlet guide vanes 6 to slightly Adjust.

In FIG. 14, as an example, the abscissa represents the dimensionless flow rate of the centrifugal compressor equipped with this device, and the ordinate represents the pressure coefficient and efficiency from the top to show the performance of the centrifugal compressor equipped with this device. As shown, it was confirmed that highly efficient operation can be performed in a wide operating range.

In FIG. 15, with the diffuser blade fixed,
The overall performance of the centrifugal compressor when only the inlet guide vanes are variable is shown. The performance of the apparatus according to the present invention shown in FIG. 14 is significantly improved compared to this figure at both large and small flow rates. That is, the effect of the present invention is clear. In the case of the pump, the same result is obtained as the dimensionless characteristic even when the rotation speed is changed.

In the embodiments shown in FIGS. 4 to 14, the example in which one unit of the arithmetic processing unit U is installed is shown, but the arithmetic processing unit may be divided into plural units according to their functions. Further, although the control drive device is divided into the first, second, and third control drive devices according to their functions, one control drive device may be used.

[0050]

As described above, according to the present invention, the unstable phenomenon that occurs when the fluid machine is operated in a flow rate range other than the design point flow rate is avoided, and the fluid machine is operated in a wide flow rate range. be able to.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a state of fluid at an outlet of an impeller.

FIG. 2 (a) is a diagram showing a relationship between a dimensionless suction flow rate and a dimensionless diffuser loss, and FIG. 2 (b) is a view showing a relationship between a dimensionless suction flow rate and a pump efficiency. is there.

FIG. 3 is a diagram showing a pressure fluctuation state in various parts of the pump.

FIG. 4 is a vertical sectional view showing a single-stage centrifugal compressor which is an example of a fluid machine with variable guide vanes according to the present invention.

FIG. 5 is a partial side view showing a single-stage centrifugal compressor which is an example of a fluid machine with variable guide vanes according to the present invention.

FIG. 6 is a block diagram showing an embodiment of a fluid machine with variable guide vanes according to the present invention.

7A and 7B are views showing a pressure hole provided on a board to which a diffuser blade is attached, where FIG. 7A is a front view and FIG. 7B is a sectional view.

FIG. 8 is a graph showing the relationship between the dimensionless flow rate and the diffuser blade angle.

FIG. 9 is a graph showing the relationship of ξ with respect to the flow angle previously obtained by the test wind tunnel.

FIG. 10 is a graph illustrating how to obtain a variation value in the fluid machine with variable guide vanes according to the present invention.

FIG. 11 is a graph showing how to obtain a threshold value in the fluid machine with variable guide vanes of the present invention.

FIG. 12 is a flowchart showing a processing procedure of the fluid machine with variable guide vanes of the present invention.

FIG. 13 is an explanatory diagram of a characteristic curve and a resistance curve of the pump.

FIG. 14 is a diagram showing the relationship between the dimensionless flow rate, efficiency and head coefficient of the present invention.

FIG. 15 is a diagram showing a relationship between a dimensionless flow rate, efficiency, and a head coefficient in the conventional technique.

[Explanation of symbols]

 DESCRIPTION OF REFERENCE NUMERALS 1 arithmetic unit 2 storage unit U arithmetic processing device 3 input device 4 diffuser blade 5 first control drive device 6 inlet guide vane 7 second control drive device 8 impeller 9 third control drive device 10 disk 11 (11-1, 11) -2, 11-3) Pressure hole

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[Procedure amendment]

[Submission date] August 7, 1995

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 6

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

The invention according to claim 6 is based on such consideration, and in a fluid machine equipped with a diffuser blade, a pressure for detecting at least the pressure surface side and the suction surface side pressure of the diffuser blade. a detection device, to set the reference flow rate, in the larger flow rate than the reference rate, and control the angle of the upper Symbol diffuser blades based on the detected pressure by the pressure detection device, in the following the reference flow rate, the pressure A variable guide vane, comprising: a control device that calculates a fluctuation value of the pressure value detected by the detection device, and controls the diffuser angle so that the fluctuation value is equal to or less than a predetermined threshold value. It is a fluid machine with.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

[0023] In the invention of claim 6, the control device, in the larger flow rate than the reference rate, and control the angle of the upper Symbol diffuser blades based on the pressure detected by the pressure detecting device, the reference flow rate or less Calculates the fluctuation value of the pressure value detected by the pressure detection device, and controls the diffuser angle so that this fluctuation value is equal to or less than a predetermined threshold value. Appropriate control is performed in the flow rate range.

Claims (6)

[Claims] 1. A fluid machine including a diffuser blade, a pressure detecting device for detecting pressure at a pressure surface side and a negative pressure surface side of the diffuser blade, and a predetermined position of the diffuser portion, and a pressure detected by the pressure detecting device. A fluid machine with variable guide vanes, comprising: an arithmetic processing unit that determines the angle of the diffuser vane based on the above; and a first control drive device that drives and controls the diffuser vane to the determined angle. 2. An input device for inputting a required operating state of the fluid machine is further provided, and the arithmetic processing unit calculates the operating state of the fluid machine so that the required performance input by the input device can be exhibited. The fluid machine with variable guide vanes according to claim 1, wherein 3. The fluid machine with variable guide vanes according to claim 1, wherein the pressure detecting device is provided on a board to which the diffuser vanes are attached. 4. An inlet guide vane and a second control drive device for driving and controlling the inlet guide vane to an angle calculated based on a predetermined arithmetic expression. 4. A fluid machine with variable guide vanes according to any one of 3 to 3. 5. The fluid machine with variable guide vanes according to claim 1, further comprising a third control drive device for controlling the rotation speed of the fluid machine. 6. A fluid machine having a diffuser vane, wherein a pressure detecting device for detecting pressure on at least a pressure surface side and a negative pressure surface side of the diffuser vane, a reference flow rate is set, and at a flow rate higher than this reference flow rate, Based on the pressure detected by the pressure detection device, the direction of the flow flowing out of the impeller is determined to control the angle of the diffuser blade, and at the reference flow rate or less, the pressure value detected by the pressure detection device is set. And a control device for controlling the diffuser angle so that the variation value becomes equal to or less than a predetermined threshold value.