CN103307008A - Design method for inducer with long and short blades of nuclear main pump - Google Patents

Abstract

The invention relates to a design method of an inducer with long and short blades. This design method is based on the general inducer, changing the blades of the inducer to the form of long and short blade intervals, and making the outlets of the long and short blades located on the same interface, thus combining the characteristics of the long and short blades and the inducer to design a A new type of inducer that can improve the velocity distribution of the liquid and improve the anti-cavitation ability of the pump.

Description

Design method of inducer with long and short blades for nuclear main pump

Technical field:

The invention relates to an inducer, in particular to an inducer with long and short blades. the

Background technique:

At present, there are two types of inducers used: one is a cylindrical inducer, and the flow area of the inlet and outlet of the inducer is the same; the other is a conical inducer, and the flow area of the inlet of the inducer is the same. The area is large and the outlet flow area is small. This structure can improve the anti-cavitation ability of the inducer itself, so it is widely used. The main function of the inducer is to improve the anti-cavitation ability of the pump. These two conventional inducers can improve the anti-cavitation ability of the pump to a certain extent, but when the flow rate of the pump is further increased, due to the increase of the flow rate The increase of the outlet velocity of the inducer leads to the decrease of the outlet pressure of the inducer, and when the inlet pressure of the impeller is too low, cavitation may occur. The cavitation phenomenon of the pump has a great impact on the normal operation of the pump. The main hazards are: 1. Changes in the energy characteristics of the machine: after a certain level, the parameters such as the efficiency, power, and flow of the machine will drop sharply. 2. Cause Noise and vibration, 3 Surface damage of wetted parts. the

In order to make the pump work normally without cavitation under a larger flow rate, the blades of the conical inducer are designed in the form of long and short blades spaced apart. the

Invention content:

In order to solve the above problems, the present invention provides a design method of an inducer with long and short blades. The inducer designed by this method can greatly improve the anti-cavitation ability of the pump and make the working range of the pump wider. the

The technical solution adopted to achieve the above purpose:

1 long blade design

1.1 Inlet diameter of inducer:

$\begin{array}{cc}{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\sqrt[\mathrm{<span\; class="notranslate">\; 3</span>}]{\frac{\mathrm{<span\; class="notranslate">\; Q</span>}}{\mathrm{<span\; class="notranslate">\; no</span>}}}& {\mathrm{<span\; class="notranslate">\; K</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; 4.5</span>}<span\; class="notranslate">\; ~</span>\mathrm{<span\; class="notranslate">\; 5.5</span>}\end{array}$

$\mathrm{<span\; class="notranslate">\; Dy</span>}<span\; class="notranslate">\; =</span>\sqrt{{{\mathrm{<span\; class="notranslate">\; D.</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}$

In the formula: D ₀ import equivalent diameter mm

QFlow m ³ /h

nspeed r/min

D _y inlet diameter D ₀ : equivalent inlet diameter

1.2 Select the imported hub ratio and hub cone angle

${\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; d</span>}}_{\mathrm{<span\; class="notranslate">\; h</span>}}}{\mathrm{<span\; class="notranslate">\; Dy</span>}}$

The hub cone angle of the inducer is generally selected from 0.16 to 0.3 The hub cone angle is generally selected from 8° to 12°

In the formula:

d _h : hub radius

d _h1 : import hub ratio

1.3 Determine the inlet and outlet angle of the inducer blade

In the formula:

β _y1 : blade inlet angle

β _y2 : outlet angle of the outer edge streamline blade

v _m1 inlet axial speed

uExit peripheral speed

v _m2 outlet axial speed

u ₂ exit peripheral speed

v _u2 Circumferential velocity

1.3 Calculation of lead, pitch and axial height

Inducer lead: S=3.14D _y tanβcy

Inducer pitch: P=S/Z

轮毂轴向高度： 

Axial height of rim:

Hub axial height:

Z: generally choose 2 (priority) or 3 a ₁ and a ₂ are the hub wrap angle and the rim wrap angle respectively

βcy: Airfoil setting angle of the rim section

1.4 blade rim wrap angle, hub wrap angle

${\mathrm{\&alpha;}}_1=360\frac{1}{t}\frac{\cos {\mathrm{\&beta;}}_{\mathrm{cy}}}{z}$ a ₂ =Δa+a ₁

In the formula:

a ₁ : Wrap angle of blade rim

a ₂ : blade hub wrap angle

Δa: blade sweep angle (60°～180°)

翼型叶栅密度(1.5～3) 

Airfoil Cascade Density (1.5～3)

2 short blade design

The number of the short blades is equal to the number of the long blades, and the short blades are placed between the long blades so that the long and short blades are arranged alternately. the

2.1 The hub height h of the short blade

h=(1/2～1/3) _h The height of the h hub is the inlet position of the blade

2.2 The inlet and outlet diameters of short blades

The design method of the inlet and outlet diameter is the same as that of the long blade, and the outlet diameter and the outlet diameter of the long blade are located on the same section

2.3 Calculation of inlet and outlet angles of short blades

D _y1 tanβ _y1 = D _h tanβ _h1 $\mathrm{the\; tan}{\mathrm{\&beta;}}_{h2}=\frac{v_{m2}}{u_2-v_{u2}}$

In the formula:

D _y1 : Long blade inlet diameter

β _y1 : Long blade inlet angle

D _h : hub diameter at the inlet position of the short blade D _h :

β _h1 : short blade inlet angle

β _h2 : short blade exit angle

2.4 Pitch and lead of short blades

The lead of the short blades is the same as that of the long blades, and the pitch becomes half of that of the long blades at the alternate arrangement. the

The beneficial effects of the invention are: further improving the anti-cavitation ability of the pump, so that the pump does not have cavitation when it works under the condition of large flow. the

Description of drawings

Fig. 1 is the axial plane projection diagram of the inducer of an embodiment of the present invention

Fig. 2 is the structure diagram of the inducer of the same embodiment

Figure 3 is a structural diagram of a nuclear main pump

In the figure: 2. inducer, 3. impeller, 4. guide vane, 5. suction steel pipe, 6. pump casing, 7. long blade, 8. long blade, 9. short blade, 10. short blade; d _h : Hub diameter at the inlet position of the short blade, d _h1 : hub diameter at the inlet position of the short blade, D _y : inlet diameter of the inducer, d _h2 : hub diameter at the outlet

Detailed ways

Figure 1 and Figure 2 together determine the shape of the inducer of this embodiment. It, like most conical inducers, has a hub (1), which is conical. The blades of the inducer are divided into two types: long blades (7), (8) and short blades (9), (10). The long and short blades are arranged alternately. The middle part of the inducer continues to the outlet, and its main purpose is to scour the wake, improve the flow of the liquid, and then improve the anti-cavitation ability of the pump. Fig. 3 is a schematic diagram of a nuclear main pump, which shows the installation position of the inducer in the nuclear main pump, and its fixing method is screw fixing. As shown in the figure below: (2) is the inducer, (3) is the impeller, (4) is the guide vane, (5) is the suction steel pipe, and (6) is the pump casing. the

Claims (2)

1. A design method of a nuclear main pump (nuclear reactor coolant pump) inducer, mainly comprising the design of the inlet and outlet angles of long and short blades, the design of the inlet and outlet diameters, the design of hub height and diameter; it is characterized in that: after the inducer Half-section long and short blades are arranged alternately, and the height of the hub of the short blades satisfies the following relationship h＝(0.3～0.5)h _h In the formula: h _h : the hub height of the long blade, in mm. 2. As stated in claim 1, the determination method of the inlet angle of the short blade is as follows: D _y1 tanβ _y1 = D _h tanβ _h1 In the formula: D _y1 : Inlet diameter of the long blade, in mm β _y1 : long blade inlet angle unit degree D _h : the diameter of the hub at the inlet position of the short blade D _h in mm β _h1 : short blade inlet angle unit degree.

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