JPH0979178A - Fluid machine with variable guide vanes - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To provide a fluid machine with variable guide vanes capable of operating a fluid machine in a wide flow rate range while avoiding an unstable phenomenon which occurs when the fluid machine is operated in a flow rate range below a design point flow rate. To do. In the fluid machine provided with the A diffuser vane 3a, and the detector S ₁ to S ₁₂ for detecting the state quantity of the fluid machine or prime mover vary based on the change in suction flow rate,
The controller 12 determines and controls the diffuser vane angle based on the relationship between the state quantity and the diffuser vane angle obtained in advance.

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 fluid pump, a blower for gas and a compressor, and more particularly to a fluid machine with an inlet guide vane and a diffuser vane.

[0002]

2. Description of the Related Art Conventionally, when centrifugal and oblique flow pumps are operated in a low flow rate range other than the design point, flow separation occurs in components such as impellers and diffusers, and due to these causes, the pumps Instability phenomenon with the piping system (surging, etc.) due to a decrease in the rate of pressure increase relative to the flow rate that can be generated.
However, there is a drawback that the operation becomes impossible. In order to solve this problem, in addition to the piping connected to the pump, a bypass (air blower in the case of a blower or compressor) piping is installed, and the bypass piping is installed at a flow rate at which the pump causes an unstable phenomenon. By opening the valve, the operation state of the pump is not changed even if the flow rate on the device side is reduced, and the like is adopted to avoid the point where the unstable phenomenon occurs.

[0003]

However, since this method avoids an unstable phenomenon on the device side, the flow rate at which the unstable phenomenon occurs in the pump is determined in advance, and when the flow rate is reached, the bypass Control must be performed to open the valve of the piping for use. Therefore, with this method, the control of the entire device cannot be performed accurately unless the flow rate at the pump instability phenomenon generation point can be accurately determined, and the characteristics when the rotational speed of the pump is changed must also be accurately determined. Since the control of the entire device cannot be performed accurately, there is a drawback in that it cannot follow up in an operating state in which the pump is continuously changed.

Further, even if the point where the unstable phenomenon occurs is avoided by opening the valve of the bypass pipe, the operating state of the pump itself does not change, so that the pump is caused to operate unnecessarily, which is an energy saving point of view. There were many problems. Furthermore, there is a drawback that the cost of the device becomes high because bypass piping and valves are required.

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 range below a design point flow rate. An object of the present invention is to provide a fluid machine with guide vanes.

[0006]

The present invention was made based on the following recognition. FIG. 1 is a schematic diagram showing a state of an impeller outlet of a fluid machine (compressor). Impeller 2
The flow directions of the fluid flowing out from are indicated by arrows a (design flow rate), b (small flow rate), and c (large flow rate). As is apparent from this figure, at flow rates other than the design point, the pressure surface side of the blades 3a of the diffuser 3 at large flow rates, and the diffuser 3 at small flow rates.
The angle of attack of the flow on the suction surface side of the blade 3a becomes excessive.
The flow separates and the loss in the diffuser increases as shown in FIG. 2 (a diagram showing the relationship between the dimensionless flow rate and the diffuser loss). As a result, the overall performance of the compressor is as shown in FIG. 3 (a diagram showing the relationship between the dimensionless flow rate and the dimensionless head coefficient), and a characteristic (unstable) that rises to the right on the small flow rate side from the design point appears. In addition to the above, surging occurs at a certain flow rate, pressure fluctuations in the pipes increase, and operation becomes impossible.

In order to solve this, the diffuser vane angle is made variable, and the diffuser vane loss is obtained by moving the diffuser vane angle so as to adapt to the flow of the impeller when the flow rate is reduced (the flow of b in FIG. 1). Can be reduced as indicated by the dashed line in FIG. As a result, the overall performance of the compressor can be improved as shown by the broken line in FIG. 3, and an unstable phenomenon can be avoided and stable characteristics can be obtained.

The present invention has been made on the basis of the above recognition, and the invention according to claim 1 is a fluid machine equipped with diffuser vanes, in which the state of the fluid machine or the prime mover changes depending on the change of the suction flow rate. A fluid machine with variable guide vanes, comprising: a detection device that detects the amount; and a control device that determines and controls the diffuser vane angle based on the relationship between the state amount and the diffuser vane angle obtained in advance. Is.

According to the study of the diffuser vanes devised by the present inventors, the optimum angle of the diffuser vanes at the impeller outlet with respect to the dimensionless suction flow rate of the pump is represented by a substantially straight line as shown in FIG. It was found that the surging phenomenon can be avoided by controlling the diffuser blades until the flow rate is 0.

In the case of a pump, the optimum angle of the diffuser vane at the impeller outlet with respect to the dimensionless suction flow rate when the rotational speed is changed is represented by almost one straight line (straight line N in FIG. 4).
₁ ) In the case of a compressor, due to the compressibility of gas, the slope of the straight line differs depending on the rotation speed (straight lines N _{1 to} N _{4 in} FIG. ₄ ). This inclination can be calculated by predicting the state of the impeller outlet.

Therefore, in any state, it is possible to operate by making the angle of the diffuser vanes optimally match the impeller outlet flow as long as the dimensionless suction flow rate of the pump is known. Further, the relationship between the state quantity having a certain correspondence relationship with the suction flow rate of the pump and the diffuser blade angle is obtained directly or directly from the relationship with the suction flow rate, and these state quantities are measured. It is also understood that the diffuser vane angle can be controlled.

Examples of such state quantities include input current, rotation speed and torque of the pump motor, suction pressure,
Fluid velocity in piping, fluid temperature difference at suction and discharge ports, noise,
When the heat generated by the compressor is cooled by a gas cooler or the like, there is a valve opening degree, and the amount of heat exchange is also an index.
Each will be described below.

1) Input Current of Electric Motor In the case of driving the electric motor, the intake flow rate can be captured to some extent by detecting the input current of the electric motor as a state quantity related to the intake flow rate. Motor power is L = η _m · η _p · V · A = ρ · g · H · Q / η where η _m : Motor efficiency η _p : Motor power factor V: Motor input voltage A: Motor input current ρ: Fluid Density H: Head Q: Suction flow rate η: Efficiency of driven machine It can be seen that the motor current is a function of suction flow rate. However, in this case, the efficiency of the driven machine decreases with a decrease in the flow rate, and since the electric motor input changes when the density of the fluid to be handled, the head, and the like change, there is a limit to the flow rate that can be captured by the electric motor input.

2) Rotational speed and torque of the electric motor The electric power of the electric motor is expressed as L = Tω. Since it is expressed as T: torque ω: angular velocity, it is possible to capture the suction flow rate to some extent by measuring the rotational angular velocity and torque of the electric motor. When the rotation speed of the electric motor is constant, it is only necessary to measure the torque.

3) Suction pressure The flow rate in the pipe is Q = A · v = A · (ρ · (Pt-Ps) / 2) ^1/2 where A: pipe cross-sectional area v: average velocity of fluid in the pipe Pt : Total pressure Ps: Static pressure. If suction is performed from the atmospheric pressure, the total pressure can be made constant, so that the suction flow rate can be known if the static pressure is known. Therefore, it is possible to capture the suction flow rate by measuring the static pressure at the inlet throttle portion of the compressor. In this case, it is necessary to correctly measure the static pressure of the suction flow except for the flow that flows backward from the impeller when the flow rate is low.

4) Discharge pressure Even if the discharge flow rate is measured, the suction flow rate can be captured. In the case of a machine that handles compressible gas, the method of measuring the density of the fluid must be added in order to obtain the suction flow rate from the discharge flow rate.However, when handling a non-compressed fluid such as a pump, the discharge flow rate is the suction flow rate. Match the flow rate.

5) Fluid velocity in piping If the fluid velocity in piping is measured, the suction flow rate can be captured as in the case of suction pressure. The flow velocity measurement includes a hot-wire anemometer, a laser velocity meter, an ultrasonic velocity meter, and the like.

6) Suction and discharge temperature In the case of a compressor, the temperature difference between the inlet and outlet changes depending on the flow rate. FIG. 5 shows the temperature difference between the inlet and outlet of a compressor along the flow rate along the horizontal axis, and it can be seen that there is a certain relationship between the temperature difference and the suction flow rate. In the case of a compressor, the work coefficient is obtained based on this temperature difference (FIG. 6), but since it shows almost the same tendency as the temperature difference, it is possible to capture the suction flow rate even if this value is measured. FIG. 6 similarly shows the results obtained with two types of rotation speeds N ₁ and N ₂ .

7) Gas cooler cooling water temperature difference When the amount of heat generated in the compressor is cooled by a gas cooler or the like,
The heat exchange amount is L = (T1-T2) · Cp · W where T1: gas cooler inlet fluid temperature T2: gas cooler inlet fluid temperature Cp: specific heat W: fluid amount Since the heat amount of the compressor is related to the suction flow rate, It is possible to capture the suction flow rate to some extent by measuring the amount of cooling heat, that is, the temperature difference between the fluids.

8) Sound It is also possible to capture the flow rate by measuring the noise generated in the compressor or the Strouhal number related to the flow velocity.

9) Valve opening Since there is a relationship between the opening of the suction or discharge valve of a device equipped with a compressor or the like and the flow rate, it is possible to capture the flow rate by measuring the valve opening. is there. As a result, if the diffuser blade angle is determined from the state quantity of the fluid machine or the prime mover that changes based on the change in the suction flow rate of the pump and the diffuser blade is controlled by the control device that can variably control the diffuser blade, the pump becomes unstable It will be possible to drive while avoiding the phenomenon.

When a control device capable of controlling the number of revolutions is provided, the diffuser vanes are controlled in accordance with the diffuser vane angle which can be determined by the state quantity of FIG. 4, and when the head does not satisfy a predetermined value, the number of revolutions is also controlled. And drive while avoiding unstable conditions. The invention according to claim 2 is the fluid machine with variable guide vanes according to claim 1, characterized in that the relationship between the suction flow rate and the diffuser blade angle is substantially linear.

The invention according to claim 3 is the fluid machine with variable guide vanes according to claim 2, wherein the linear relationship has a gradient determined by the rotational speed of the impeller. The invention according to claim 4 is characterized in that the control device controls the rotational speed of the fluid machine when the head does not satisfy a predetermined value when the diffuser blade angle is changed. 3 is a fluid machine with variable guide vanes. According to a fifth aspect of the present invention, the fluid machine has an inlet guide vane, and the controller controls the inlet guide vane of the fluid machine when the head does not satisfy a predetermined value when the diffuser vane angle is changed. The fluid machine with variable guide vanes according to any one of claims 1 to 4, wherein the angle is changed.

In the above description, the relationship between the suction flow rate and the diffuser blade angle was experimentally obtained, but this relationship can also be theoretically obtained. The invention of claim 6 has been made paying attention to this, and in a fluid machine equipped with a diffuser blade, a detection device for detecting the state quantity of the fluid machine or the prime mover which changes based on a change in the suction flow rate,
A fluid machine with variable guide vanes, comprising: a controller that controls the diffuser vane angle from the state quantity detected by the detector based on the following relationship between the suction flow rate and the diffuser vane angle. . α = arctan (Q / (K ₁ N−K ₂ Q)) (1) The symbols here are as follows. alpha: diffuser blades angle Q: intake flow rate ^{_{K 1 = (πD 2) 2}} σb 2 B: constant N: rotational speed K ₂ = cotβ _2: constant sigma: Slip factor beta _2: feathers from the circumferential exit angle D _2: Impeller outer diameter b ₂ : Impeller exit width B: Blockage coefficient

According to a seventh aspect of the present invention, in a fluid machine equipped with diffuser vanes, a detection device for detecting the state quantity of the fluid machine or the prime mover which changes based on the change of the suction flow rate, and the suction flow rate from the state quantity. A variable guide comprising a controller for controlling the diffuser blade angle from the state quantity detected by the detector based on the following relationship between the suction flow rate and the rotation speed and the diffuser blade angle. It is a fluid machine with blades. α = arctan (Q / (K ₁ N−K ₂ Q)) The symbols here are as follows. alpha: diffuser blades angle Q: intake flow rate ^{_{K 1 = (πD 2) 2}} σb 2 B: constant N: rotational speed K ₂ = cotβ _2: constant sigma: Slip factor beta _2: feathers from the circumferential exit angle D _2: Impeller outer diameter b ₂ : Impeller exit width B: Blockage coefficient

According to an eighth aspect of the present invention, in a fluid machine equipped with a diffuser blade, a detection device for detecting a state quantity of a fluid machine or a prime mover that changes based on a change in a suction flow rate and a pressure ratio between an inlet and an outlet, A variable guide comprising a controller for controlling the diffuser blade angle from the state quantity and the pressure ratio detected by the detection device based on the following relationship between the suction flow rate and pressure ratio and the diffuser blade angle. It is a fluid machine with blades.

(Equation 3) The symbols used here are as follows. α: Diffuser blade angle Q: Suction flow rate K ₁ = (πD ₂ ) ² σb ₂ B: Constant N: Rotational speed K ₂ = cot β ₂ : Constant P _r : Compressor inlet / outlet pressure ratio κ: Specific heat ratio σ: Slip coefficient β ₂ : Blade exit angle from the circumferential direction D ₂ : Impeller outer diameter b ₂ : Impeller exit width B: Blockage coefficient

According to a ninth aspect of the present invention, in a fluid machine equipped with a diffuser blade, a detecting device for detecting a state quantity of a fluid machine or a prime mover that changes based on a change in suction flow rate and a pressure ratio between an inlet and an outlet, The suction flow rate is calculated from this state quantity, and based on the following relationship between the suction flow rate, the rotation speed and the pressure ratio and the diffuser blade angle, the diffuser blade angle is detected from the state quantity, the rotation speed and the pressure ratio detected by the detection device. A fluid machine with variable guide vanes, comprising:

(Equation 4) The symbols used here are as follows. α: Diffuser blade angle Q: Suction flow rate K ₁ = (πD ₂ ) ² σb ₂ B: Constant N: Rotational speed K ₂ = cot β ₂ : Constant P _r : Compressor inlet / outlet pressure ratio κ: Specific heat ratio σ: Slip coefficient β ₂ : Blade exit angle from the circumferential direction D ₂ : Impeller outer diameter b ₂ : Impeller exit width B: Blockage coefficient

According to a tenth aspect of the present invention, in a fluid machine equipped with diffuser vanes, a detection device for detecting the state quantity of the fluid machine or the prime mover that changes based on a change in the suction flow rate, and this state quantity and a previously determined quantity. A fluid machine with variable guide vanes, comprising: a controller for controlling the area between the diffuser vanes based on the relationship between the suction flow rate and the area between the diffuser vanes. The configurations of the inventions of claims 6 to 10 are based on the following considerations. Assuming that the flow rate at the impeller outlet is Q ₂ , the impeller outer diameter is D ₂ , the impeller outlet width is b ₂ , and the blockage coefficient of the impeller outlet portion is B, the radial velocity component Cm _{2 at the} impeller outlet is Cm ₂ = Q ₂ / (πD ₂ b ₂ B) (3) Assuming the fluid is incompressible, Q ₂ is equal to the inlet flow rate Q, so Cm ₂ = Q / (πD ₂ b ₂ B) (4).

When the fluid flows in the diffuser, the velocity near the wall surface becomes smaller in the actual flow due to the boundary layer than in the main flow. Assuming that the velocity of the main flow is U and the velocity in the boundary layer is u, and the velocity in the boundary layer is slower than the velocity of the main flow, the insufficient flow rate is

(Equation 5) It is represented by When the excluded thickness is δ ^* and a flow equal to the main flow velocity U flows in this thickness portion, the flow rate is Uδ
Expressed as ^* . Since both are equal, the excluded thickness of the boundary layer is

(Equation 6) It is expressed as (For example, "Fluid mechanics (2)" (Corona Corp.), "Mechanics of internal flow" (Yokendo))

Generally, the average velocity in the channel cross section is calculated in consideration of the reduction of the channel width due to the excluded thickness. In the case of a fluid machine, the flow out of the impeller is in the channel width direction. Not uniform (For example, the Japan Society of Mechanical Engineers, Vol. 44, 38
No. 4, "Study on relative velocity distribution and performance of centrifugal impeller" Fig. 20), the region slower than the velocity of the mainstream becomes even larger than the thickness due to the boundary layer. Therefore, with respect to the geometrical channel width, the velocity in the channel cross section will be underestimated unless the channel width is corrected by the boundary layer and velocity distortion, and the flow angle calculated based on it will also be in error. Grows larger. Therefore, in the present invention, the blockage coefficient is taken into consideration as the correction amount of the flow path width.

On the other hand, the peripheral velocity component Cu _{2 at the} outlet of the impeller
Is the slip coefficient σ and the impeller exit angle from the circumferential direction is β
₂ and U ₂ is the impeller peripheral speed, it can be expressed as Cu ₂ = σU ₂ −Cm ₂ cotβ ₂ (7). Therefore, the flow angle at the impeller outlet, that is, the diffuser blade angle α is α = arctan (Cm ₂ / Cu ₂ ) = arctan (Q / (πσD ₂ U ₂ b ₂ B-Qcotβ ₂ )) (8) . Here, K ₁ = (πD ₂ ) ² σb ₂ b ₂ B, K ₂ = cotβ ₂ (9), and N is the number of revolutions, α = arctan (Q / (K ₁ N−K ₂ Q) ) (10) On the other hand, in the case of a compressible fluid, the impeller outlet flow rate Q _2
Let P _{r be} the pressure ratio at the compressor inlet / outlet and κ be the specific heat ratio.

(Equation 7) Can be expressed as Therefore,

(Equation 8) Therefore, from equations (5) and (10), the impeller outlet flow angle, that is, the diffuser blade angle α is

[Equation 9] Becomes

As described above, the diffuser flow is detected by the detector for detecting the suction flow rate and the rotation speed in the fluid machine handling the incompressible fluid, and the suction flow rate, the rotation speed and the pressure ratio between the inlet and the outlet in the machine handling the compressible fluid. By calculating the angle and controlling the diffuser vanes to match the flow angle, flow separation can be suppressed and surging can be avoided.

According to a tenth aspect of the present invention, in a fluid machine equipped with diffuser vanes, a detecting device for detecting the state quantity of the fluid machine or the prime mover which changes based on a change in the suction flow rate, and this state quantity and a previously determined quantity. A fluid machine with variable guide vanes, comprising: a controller for controlling the area between the diffuser vanes based on the relationship between the suction flow rate and the area between the diffuser vanes.

The basic idea of the present invention is as follows. The area formed between the diffuser blades is A. The velocity passing through this area is expressed as K ₁ C, where C is the absolute velocity of the exit of the impeller, and K ₁ is the deceleration rate in the section from the impeller to the diffuser blade, where K ₁ is the deceleration coefficient. Now C is the impeller outlet radial velocity component Cm _2, a circumferential velocity component and Cu _2,

(Equation 10) It is expressed as Flow rate Q passing between these blades
₂ is represented as Q ₂ = K ₁ CA (15). The circumferential velocity component Cu ₂ is expressed as Cu ₂ = σU ₂ −Cm ₂ cotβ ₂ (16) as in the equation (5).

Therefore, Q ₂ is

[Equation 11] Becomes On the other hand, since Q ₂ is expressed by the equation (3) as Q ₂ = πD ₂ b ₂ B · Cm ₂ (18), the impeller outlet radial velocity component Cm ₂ is Cm ₂ = Q / πD ₂ b ₂ B (19) Therefore,

(Equation 12) Becomes

Here, K ₂ = πD ₂ b ₂ B (21) K ₃ = (K ₂ σπD ₂ ) ² (22) K ₄ = 2K ₂ σπD ₂ cotβ ₂ (23) K ₅ = 1 + cot ² β ₂ ( 24) and the fluid is incompressible, the suction flow rate is Q, and the rotation speed is N, the area A is

(Equation 13) It can be expressed as. In the case of a compressible fluid, if the pressure ratio at the compressor inlet / outlet is Pr and the specific heat ratio is κ, the flow rate at the impeller outlet is simply

[Equation 14] Becomes

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. 7 to 9 are views showing a single-stage centrifugal compressor to which the present invention is applied, FIG. 7 is a longitudinal sectional view thereof, FIG. 8 is a partial side view thereof, and FIG. 9 is a block diagram including a control system. is there. this is,
Kinetic energy is given to the fluid flowing in from the suction pipe 1 by the impeller 2, sent to the diffuser 3 to increase the pressure, and sent out from the scroll 4 to the discharge pipe 5. The main shaft of the impeller is connected to the electric motor M. There is. A plurality of fan-shaped inlet guide vanes 6 are arranged in the suction pipe 1 in the circumferential direction, and an actuator 8 is connected thereto via a transmission mechanism 7. The diffuser vane 3 a is arranged on the diffuser 3 on the downstream side, which is also connected to the actuator 10 via the transmission mechanism 9. These actuators 8 and 10 are provided with a control drive device 11, to which a CPU 12 is connected. This compressor is provided with a gas cooler 13 that cools the fluid.

Sensors are attached to various parts of the main body or attached machine of this compressor. That is, S ₁ is an ammeter that detects the input current of the electric motor, S ₂ and S ₃ are torque sensors and rotation speed sensors that detect the torque of the spindle, and S _2
4 is a suction pressure sensor provided in the suction pipe 1, S ₅ to S ₇ are discharge pressure sensors, a fluid velocity sensor and a fluid temperature sensor provided in the discharge pipe, and S ₈ is a suction pressure provided in the suction pipe 1. temperature sensor, inlet temperature sensor at the outlet of the S ₉ and S ₁₀ is a gas cooler 13, S ₁₁ is a sound sensor, S _{1 2}
Is a valve opening meter. These sensors S ₁ -S ₁₂ are connected to a detector interface 14 via which C
It is input to the PU 12.

FIG. 10 is a flow chart showing the processing procedure of the fluid machine with variable guide vanes of the present invention. First, in step 1, the rotation speed of the impeller 2 is set to an appropriate value that does not exceed a predetermined limit. Next, in step 2, the angle α of the inlet guide vane 6 is determined from the rotational speed N of the impeller 2, the required flow rate Q, the head H and the like. Next, in step 3, the state quantity is measured, and in step 4, the diffuser blade angle is determined based on the relationship shown in FIG. 4 or the calculation formula described above in step 4 ′.

Next, in step 5, the control drive unit and the actuator are operated to control the angle of the inlet guide vane 6. Next, in step 6, it is judged whether or not the head H has a predetermined value, and if it is the predetermined value, the operation is continued there.
When the head is not the predetermined value, the magnitude relationship between the head and the predetermined value is determined in step 7, and when the head is small, the angle of the inlet guide vane 6 is decreased in step 8.

Next, at step 9, it is judged whether or not the angle of the inlet guide vane is the lower limit value, and if NO, the process returns to step 3 and the subsequent steps are repeated. Further, if YES, it is determined in step 10 whether the rotation speed is the limit value, and if YES, the operation is continued as it is.
In this case, the desired head cannot be obtained. If NO, the number of revolutions is increased in step 11 (by a predetermined amount).
Increase and return to step 3 to repeat the subsequent steps.

If it is determined in step 7 that the head is larger than the predetermined value, the inlet guide vane angle is increased in step 12. Next, in step 13, it is determined whether or not the entrance guide vane angle is the upper limit value, and if NO, step 3
Return to and repeat the subsequent steps. Also, YES
If so, the number of revolutions is reduced (by a predetermined amount) in step 14, the process returns to step 3, and the subsequent steps are repeated.

FIG. 11 shows a comparison between the overall performance of the conventional device with the diffuser vanes fixed and the performance of the device according to the present invention. It is understood that the performance of the device according to the present invention can be stably operated up to near the shutoff flow rate as compared with the conventional one.

The relationship between the state quantity and the diffuser vane angle can be obtained from the relationship with the suction flow rate as described above, but it goes without saying that the relationship between the two can be directly obtained and used. is there.

[0044]

As described above, according to the present invention, instability phenomena such as surging that occur when the fluid machine is operated in the flow rate range below the design point flow rate are avoided, and the fluid machine is operated in a wide flow rate range. You can drive in.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a relationship between a dimensionless flow rate and a diffuser loss.

FIG. 3 is a diagram showing a relationship between a dimensionless flow rate and a dimensionless head coefficient.

FIG. 4 is a diagram showing a relationship between a suction flow rate or state quantity and a diffuser blade angle.

FIG. 5 is a graph showing the relationship between the flow rate and the temperature difference between the inlet and the outlet of the compressor.

FIG. 6 is a graph showing the relationship between flow rate and work coefficient.

FIG. 7 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. 8 is a partial side view of FIG.

FIG. 9 is a block diagram including a control system of a fluid machine with variable guide vanes according to the present invention.

FIG. 10 is a flowchart showing a processing procedure of the fluid machine with variable guide vanes of the present invention.

FIG. 11 is a graph illustrating effects of the fluid machine with variable guide vanes according to the embodiment of the present invention.

[Explanation of symbols]

2 the impeller 3 diffuser portion 3a diffuser blades 8,10 actuator S ₁ to S ₁₂ detector 12 control device

Claims (12)

[Claims] 1. A fluid machine including a diffuser blade, a detection device for detecting a state quantity of a fluid machine or a prime mover that changes based on a change in suction flow rate, and a relationship between the state quantity and a diffuser blade angle obtained in advance. And a controller for determining and controlling the diffuser blade angle based on the above. 2. The fluid machine with variable guide vanes according to claim 1, wherein the relationship between the suction flow rate and the diffuser blade angle is a substantially linear relationship. 3. The fluid machine with variable guide vanes according to claim 2, wherein the linear relationship has a gradient determined by the rotational speed of the impeller. 4. The control device controls the rotational speed of a fluid machine when the head does not satisfy a predetermined value when the diffuser blade angle is changed. A fluid machine with variable guide vanes according to. 5. The fluid machine has an inlet guide vane, and the controller changes the inlet guide vane angle of the fluid machine when the head does not satisfy a predetermined value when the diffuser vane angle is changed. A fluid machine with variable guide vanes according to any one of claims 1 to 4. 6. A fluid machine equipped with diffuser vanes, a detection device for detecting a state quantity of a fluid machine or a prime mover that changes based on a change in suction flow rate, and a suction flow rate calculated from the state quantity, and the suction flow rate and the diffuser. A fluid machine with variable guide vanes, comprising: a controller for controlling the diffuser vane angle from the state quantity detected by the detector based on the following relationship with the vane angle. α = arctan (Q / (K ₁ N−K ₂ Q)) The symbols here are as follows. alpha: diffuser blades angle Q: intake flow rate ^{_{K 1 = (πD 2) 2}} σb 2 B: constant N: rotational speed K ₂ = cotβ _2: constant sigma: Slip factor beta _2: feathers from the circumferential exit angle D _2: Impeller outer diameter b ₂ : Impeller exit width B: Blockage coefficient 7. A fluid machine equipped with diffuser vanes, a detection device for detecting a state quantity of a fluid machine or a prime mover that changes based on a change in suction flow rate, and a suction flow rate calculated from the state quantity, and a suction flow rate and a rotation speed. A fluid machine with variable guide vanes, comprising: a controller for controlling the diffuser vane angle from the state quantity detected by the detector based on the following relationship between the number and the diffuser vane angle. α = arctan (Q / (K ₁ N−K ₂ Q)) The symbols here are as follows. alpha: diffuser blades angle Q: intake flow rate ^{_{K 1 = (πD 2) 2}} σb 2 B: constant N: rotational speed K ₂ = cotβ _2: constant sigma: Slip factor beta _2: feathers from the circumferential exit angle D _2: Impeller outer diameter b ₂ : Impeller exit width B: Blockage coefficient 8. A fluid machine equipped with diffuser vanes, a detector for detecting a state quantity of a fluid machine or a prime mover that changes based on a change in suction flow rate and a pressure ratio at an inlet and an outlet, and a suction flow rate, a pressure ratio and a diffuser. A fluid machine with variable guide vanes, comprising: a controller for controlling the diffuser vane angle from the state quantity and the pressure ratio detected by the detector based on the following relationship with the vane angle. [Equation 1] The symbols used here are as follows. α: Diffuser blade angle Q: Suction flow rate K ₁ = (πD ₂ ) ² σb ₂ B: Constant N: Rotational speed K ₂ = cot β ₂ : Constant P _r : Compressor inlet / outlet pressure ratio κ: Specific heat ratio σ: Slip coefficient β ₂ : Blade exit angle from the circumferential direction D ₂ : Impeller outer diameter b ₂ : Impeller exit width B: Blockage coefficient 9. A fluid machine having a diffuser vane, a detector for detecting a state quantity and a pressure ratio of an inlet and an outlet of a fluid machine or a prime mover which changes based on a change in suction flow rate, and a suction flow rate from the state quantity. Based on the following relationship between the suction flow rate, the rotation speed and the pressure ratio, and the diffuser blade angle, the controller for controlling the diffuser blade angle from the state quantity, the rotation speed, and the pressure ratio detected by the detection device. A fluid machine with a variable guide vane, which is provided. [Equation 2] The symbols used here are as follows. α: Diffuser blade angle Q: Suction flow rate K ₁ = (πD ₂ ) ² σb ₂ B: Constant N: Rotational speed K ₂ = cot β ₂ : Constant P _r : Compressor inlet / outlet pressure ratio κ: Specific heat ratio σ: Slip coefficient β ₂ : Blade exit angle from the circumferential direction D ₂ : Impeller outer diameter b ₂ : Impeller exit width B: Blockage coefficient 10. A fluid machine having a diffuser vane, a detection device for detecting a state quantity of a fluid machine or a prime mover that changes based on a change in suction flow rate, the state quantity, and a suction flow rate and a diffuser vane determined in advance. And a controller for controlling the area between the diffuser blades based on the relationship with the area between them. 11. A fluid machine equipped with diffuser vanes, a detector for detecting a state quantity of a fluid machine or a prime mover that changes based on a change in suction flow rate, and a detector for detecting a pressure ratio between an inlet and an outlet, A control device for controlling the area between the diffuser blades based on the relationship between the suction flow rate, the pressure ratio, and the area between the diffuser blades, which are obtained in advance from the state quantity and the pressure ratio detected by the detector. A fluid machine with variable guide vanes, characterized in that 12. A fluid machine equipped with diffuser vanes, a detector for detecting a state quantity and a rotational speed of a fluid machine or a prime mover that changes based on a change in suction flow rate, and a detector for detecting a pressure ratio between an inlet and an outlet. And a controller for controlling the diffuser blade angle and the area between the diffuser blades in parallel from the state quantity, the number of revolutions and the pressure ratio detected by these detectors. Fluid machinery.