阅读说明：本技术 一种减振降噪的混流泵或轴流泵的设计方法 (Design method of vibration and noise reduction mixed flow pump or axial flow pump ) 是由 林坤 陈喜阳 彭玉成 李少斌 张克危 张双全 孙立宾 李彬 吴光焱 陈艳伟 于 2020-06-23 设计创作，主要内容包括：本发明公开了一种减振降噪的混流泵或轴流泵的设计方法,涉及水利发电设备技术领域。本发明的设计方法是将混/轴流泵的叶片从轮毂到轮缘的各个流面上的叶型相对于上一个叶型在圆周方向上同向转动相同角度,叶片在轮缘处的流面上的叶型相对于叶片在轮毂处的流面上的叶型转动角度为25°-50°；增加混流泵的叶片的数量,增加的数量为同类型常规混/轴流泵的叶片数量的50%-100%。本发明提出了一种新型的叶片形状的设计,可以(但不限于)以传统设计方法所得的叶片为基础,将从轮毂到轮缘的各个流面上的叶型依次相对于上一个叶型在圆周方向转动一定角度。使泵的水力振动得到明显较低,产品减振效果明显,噪声低。(The invention discloses a design method of a vibration and noise reduction mixed flow pump or axial flow pump, and relates to the technical field of hydropower equipment. The design method of the invention is that the vane profile on each flow surface of the vane from the hub to the rim of the mixing/axial-flow pump rotates the same angle in the same direction in the circumferential direction relative to the previous vane profile, the rotation angle of the vane profile on the flow surface of the vane at the rim relative to the vane profile on the flow surface of the vane at the hub is 25-50 degrees; the number of the blades of the mixed flow pump is increased, and the increased number is 50% -100% of the number of the blades of the same type of conventional mixed/axial flow pump. The invention provides a novel blade shape design, which can (but is not limited to) rotate blade profiles on each flow surface from a hub to a rim by a certain angle relative to the previous blade profile in the circumferential direction on the basis of the blade obtained by the traditional design method. The hydraulic vibration of the pump is obviously low, the vibration reduction effect of the product is obvious, and the noise is low.)

1. A design method of a mixed flow pump for vibration and noise reduction is characterized in that: the method comprises the following steps:

rotating the blade profile of each flow surface of the blade from the hub to the rim of the mixed flow pump in the same direction by the same angle delta phi relative to the previous blade profile in the circumferential direction, wherein the rotating angle phi of the blade profile of the flow surface of the blade at the rim relative to the blade profile of the flow surface of the blade at the hub is 25-50 degrees;

increasing the number of blades of the mixed flow pump, wherein the increased number is 50-100% of the number of blades of the same type of conventional mixed flow pump;

the blades are impeller blades and/or guide vane blades.

2. A method of designing a vibration and noise reducing mixed flow pump as defined in claim 1, wherein: the vane profile on each flow surface of the impeller blade from the hub to the rim is sequentially rotated in the circumferential direction relative to the previous vane profile in the opposite direction to the vane profile on each flow surface of the guide vane blade from the hub to the rim.

3. A method of designing a vibration and noise reducing mixed flow pump as defined in claim 1, wherein: the impeller blades are arranged in a backswept mode, specifically, the blade profile at the wheel edge rotates backwards by an angle relative to the blade profile at the wheel hub, and the backward rotation specifically refers to a direction opposite to the rotation direction of the impeller.

4. A method for designing a vibration and noise reducing mixed flow pump as defined in claim 1 or 3, wherein: the guide vane blades are arranged in a forward tilting mode, the forward tilting mode specifically means that the blade profile at the wheel edge rotates forwards by an angle relative to the blade profile at the wheel hub, and the forward rotation specifically means the direction the same as the rotation direction of the impeller.

5. A design method of an axial flow pump for vibration and noise reduction is characterized in that: the method comprises the following steps:

rotating the blade profile of each flow surface of the blades of the axial flow pump from the hub to the rim by the same angle delta phi in the same direction in the circumferential direction relative to the previous blade profile, wherein the rotating angle phi of the blade profile on the flow surface of the blades at the rim relative to the blade profile on the flow surface of the blades at the hub is 25-50 degrees;

increasing the number of blades of the axial flow pump, wherein the increased number is 50% -100% of the number of blades of the same type of conventional axial flow pump;

the blades are impeller blades and/or guide vane blades.

6. The design method of the vibration and noise reduction axial flow pump according to claim 5, characterized in that: the vane profile on each flow surface of the impeller blade from the hub to the rim is sequentially rotated in the circumferential direction relative to the previous vane profile in the opposite direction to the vane profile on each flow surface of the guide vane blade from the hub to the rim.

7. The design method of the vibration and noise reduction axial flow pump according to claim 5, characterized in that: the impeller blades are arranged in a backswept mode, specifically, the blade profile at the wheel edge rotates backwards by an angle relative to the blade profile at the wheel hub, and the backward rotation specifically refers to a direction opposite to the rotation direction of the impeller.

8. A method of designing a vibration and noise reducing axial flow pump according to claim 5 or 7, wherein: the guide vane blades are arranged in a forward tilting mode, the forward tilting mode specifically means that the blade profile at the wheel edge rotates forwards by an angle relative to the blade profile at the wheel hub, and the forward rotation specifically means the direction the same as the rotation direction of the impeller.

Technical Field

The invention relates to the technical field of hydroelectric power generation equipment, in particular to a design method of a vibration and noise reduction mixed flow pump or axial flow pump.

Background

The hydraulic design task of the mixing/axial-flow pump is to determine main structural parameters of an impeller, a water suction chamber, a water pressing chamber and other flow passage components, wherein the determination of the hydraulic parameters of blades and guide vanes of the impeller has great influence on the hydraulic efficiency, the cavitation resistance, the noise control of a pump station and the like of the pump. In the design of mixed flow pump and axial flow pump, in order to make the radial component of the acting force of the blade on the water flow smaller and satisfy the assumption that the flow state is close to the independence of the flow surface, the inlet and outlet edges of the blade are always close to the vertical direction of the water flow. It is always endeavored to arrange the blade inlet/outlet edges in one axial plane. Even if the blade wrap angles differ in the flow surfaces from the hub to the rim, it is not possible to arrange the inlet and outlet edges in one axial plane each. Designers also always consider the inlet and outlet sides together so that they are each as close as possible to being in one axial plane. When hydraulic design is carried out by the processing mode, each flow surface can be calculated respectively, the design difficulty is reduced, and good hydraulic performance is easy to obtain. Meanwhile, the blade has better manufacturability, and is convenient to process additionally. However, the blade thus obtained has a poor vibration damping effect. The product with higher requirement on noise cannot be met.

Disclosure of Invention

The invention aims to solve the problems that the design vibration reduction effect of mixed flow pump blades is poor and the product with higher noise requirement cannot be met in the prior art. The invention provides a novel blade shape design, which can (but is not limited to) rotate blade profiles on each flow surface from a hub to a rim by a certain angle relative to the previous blade profile in the circumferential direction on the basis of the blade obtained by the traditional design method. The hydraulic vibration of the pump is obviously low, the vibration reduction effect of the product is obvious, and the noise is low.

In order to solve the problems in the prior art, the invention is realized by the following technical scheme:

a design method of a mixed flow pump for vibration and noise reduction is characterized in that: the method comprises the following steps:

rotating the blade profile of each flow surface of the blade from the hub to the rim of the mixed flow pump in the same direction by the same angle delta phi relative to the previous blade profile in the circumferential direction, wherein the rotating angle phi of the blade profile of the flow surface of the blade at the rim relative to the blade profile of the flow surface of the blade at the hub is 25-50 degrees;

increasing the number of blades of the mixed flow pump, wherein the increased number is 50-100% of the number of blades of the same type of conventional mixed flow pump;

the blades are impeller blades and/or guide vane blades.

The vane profile on each flow surface of the impeller blade from the hub to the rim is sequentially rotated in the circumferential direction relative to the previous vane profile in the opposite direction to the vane profile on each flow surface of the guide vane blade from the hub to the rim.

The impeller blades are arranged in a backswept mode, specifically, the blade profile at the wheel edge rotates backwards by an angle relative to the blade profile at the wheel hub, and the backward rotation specifically refers to a direction opposite to the rotation direction of the impeller.

The guide vane blades are arranged in a forward tilting mode, the forward tilting mode specifically means that the blade profile at the wheel edge rotates forwards by an angle relative to the blade profile at the wheel hub, and the forward rotation specifically means the direction the same as the rotation direction of the impeller.

The invention also provides a design method of the vibration and noise reduction axial flow pump, and solves the problems that the design vibration reduction effect of the axial flow pump blade is poor and the product with higher noise requirement cannot be met in the prior art. The invention provides a novel blade shape design, which can (but is not limited to) rotate blade profiles on each flow surface from a hub to a rim by a certain angle relative to the previous blade profile in the circumferential direction on the basis of the blade obtained by the traditional design method. The hydraulic vibration of the pump is obviously low, the vibration reduction effect of the product is obvious, and the noise is low.

A design method of an axial flow pump for vibration and noise reduction is characterized in that: the method comprises the following steps:

rotating the blade profile of each flow surface of the blades of the axial flow pump from the hub to the rim by the same angle delta phi in the same direction in the circumferential direction relative to the previous blade profile, wherein the rotating angle phi of the blade profile on the flow surface of the blades at the rim relative to the blade profile on the flow surface of the blades at the hub is 25-50 degrees;

increasing the number of blades of the axial flow pump, wherein the increased number is 50% -100% of the number of blades of the same type of conventional axial flow pump;

the blades are impeller blades and/or guide vane blades.

The vane profile on each flow surface of the impeller blade from the hub to the rim is sequentially rotated in the circumferential direction relative to the previous vane profile in the opposite direction to the vane profile on each flow surface of the guide vane blade from the hub to the rim.

The impeller blades are arranged in a backswept mode, specifically, the blade profile at the wheel edge rotates backwards by an angle relative to the blade profile at the wheel hub, and the backward rotation specifically refers to a direction opposite to the rotation direction of the impeller.

The guide vane blades are arranged in a forward tilting mode, the forward tilting mode specifically means that the blade profile at the wheel edge rotates forwards by an angle relative to the blade profile at the wheel hub, and the forward rotation specifically means the direction the same as the rotation direction of the impeller.

Compared with the prior art, the beneficial technical effects brought by the invention are as follows:

1. in the prior art, the shape of the cylindrical blade from the back shroud (hub) to the front shroud (rim) is identical, and the whole blade can be a cylindrical surface, i.e. a twisted blade. In both mixed and axial flow pumps, the blades must be twisted because the blade angle must be different on different streamlines from the hub to the rim. The blade proposed by the patent is based on the traditional twisted blade, and is processed again, the relative position of the blade profile on different flow surfaces from the hub to the rim in the circumferential direction is changed, and the angles of the blade profiles, such as the blade placement angle and the liquid flow angle, are not related. After the relative position of the blade profile in the circumferential direction on different flow surfaces from the hub to the rim is changed, the flow conditions are changed, the mutual influence degree among the flow surfaces is redistributed, the water conservancy vibration of the pump is obviously reduced, the vibration reduction effect of the product is obvious, and the noise is low.

2. In the application, the blade profile on each flow surface of the impeller blade or the guide vane blade from the hub to the rim sequentially rotates at a certain angle relative to the previous blade profile in the circumferential direction, and the optimal value of the blade or the guide vane blade for different design objects can be determined only by performing complex calculation, such as CFD analysis, and comprehensively considering indexes such as efficiency, cavitation, vibration, strength and the like and the limitation of materials and process conditions. In a trend, the larger the angle of sweep back or rake forward, the better the damping effect, but the performance in terms of efficiency, cavitation, etc. is adversely affected, and this effect increases with increasing sweep back or rake angle. This effect is not significant when the sweep angle is not too large, but increases with increasing angle. Meanwhile, the larger the angle is, the greater the processing difficulty is, and the strength and rigidity of the blade are weakened. Therefore, for different engineering projects, due to different requirements on efficiency and cavitation indexes and different adopted processing technologies and equipment, the limitation on the sweepback angle is different. In most cases, the optimum sweep angle is approximately 25 to 50 degrees. And the higher the specific speed of the pump, the greater the optimum sweep angle.

3. The number of blades, as well as the sweep angle, is limited by efficiency, cavitation, intensity and process conditions, which need to be determined for the specific subject's specifications. In conventional designs, the number of vanes is determined based on the specific speed of the pump. In most cases, the blade ratio is increased by 50% to 100% from the conventional value for vibration damping. In hydraulic design, the density of the blade cascade has an optimal value for a certain specific rotating speed. Under the condition of keeping a certain density of the blade cascade, the number of the blades is increased, and the length of the blades is reduced. If blade length is understood to be the distance from the hub to the rim (which depends on the specific speed of the pump), the sweep angle is related to the blade length, the longer the blade the greater the sweep angle.

4. The difference between the impeller blade and the guide vane blade is that the impeller adopts a backswept mode, namely, the blade profile at the wheel edge rotates backwards (by taking the rotation direction of the impeller as the front) by an angle relative to the blade profile at the wheel hub. The guide vane is opposite and is forward-inclined, namely the edge of the guide vane rotates forwards at a certain angle relative to the hub. Of course, if the impeller is forward-inclined and the guide vanes are backward-swept, the damping effect should be the same, but the backward-swept impeller is more suitable from the viewpoint of deformation of the blades after being stressed. Especially for an open impeller, the clearance between the impeller blade and the pump shell is very small, the diameter of the forward-inclined blade is increased after the forward-inclined blade is stressed (including hydrodynamic force and centrifugal force), and the forward-inclined blade is easy to rub the pump shell, so that the safety is influenced.

Drawings

FIG. 1 is a schematic structural view of a conventional impeller blade;

FIG. 2 is a schematic structural view of a conventional guide vane blade;

FIG. 3 is a schematic diagram of the forward pitch of the impeller blades of the present invention;

FIG. 4 is a schematic view of the backswept configuration of the impeller blades of the present invention;

FIG. 5 is a schematic structural view of a guide vane blade of the present invention;

FIG. 6 is a projection of the impeller blades in a plane perpendicular to the pump axis;

FIG. 7 is a comparative isometric view of an impeller blade of the present invention and a conventional impeller blade.

Reference numerals: 1. impeller shaft side picture, 2, impeller blade inlet edge, 3, conventional impeller blade, 4, flow surface, 5, shaft surface streamline, 6, impeller blade outlet edge, 7, conventional impeller blade shaft surface projection, 8, conventional impeller blade plane projection, 9, guide vane shaft side picture, 10, guide vane inlet edge, 11, conventional guide vane blade, 12, conventional guide vane blade shaft surface projection, 13, conventional guide vane plane projection, 14, guide vane outlet edge, 15, impeller blade, 16, impeller blade shaft surface projection, 17, impeller blade plane projection, 18, guide vane blade, 19, guide vane blade shaft surface projection, 20, guide vane blade horizontal projection.

Detailed Description

The technical scheme of the invention is further elaborated in the following by combining the drawings in the specification.