Impeller radial-axial turbines
(57) Abstract:The impeller is designed to work with your device, protecting his blades from cavitation erosion during turbine operation with a significant deviation of the head from the settlement. This device has an intake channel passing through the impeller shaft connected therewith, the collector, the branching tubes that run along each blade and bring the air to the means for entering air flow part. These tools are made in the form of hollow ribs, each of which extends from the inlet edges of the blades in the direction of the streamlines in the flow part at the design mode and the rear edge has at least one hole for air release. When this edge on each blade is located with its front edge at a distance from the hub, equal to 0.2 and 0.8 of the length of the projection of the input edge of the blade to the axis of the impeller, and the edge length of 0.05 to 0.2 from the nominal diameter of the impeller. Such a device provides active suppression of cavitation during turbine operation in modes that differ significantly from those estimated. 3 Il. The invention relates to hydromelioration and Mauro hydro or during operation in the starting period at lowered pressures.The main cavitation destruction radial-axial wheels happen on the rear surfaces of the blades. During turbine operation at rated pressure zone of cavitation damage may appear directly behind the entrance edges of the blades of the wheel rim, when working at higher pressures the cavitation process in this area intensified, moreover, there is a zone of cavitation damage, displaced along the rim in the direction of the output edges, and when working on low pressure area is formed cavitation damage near the output edges of the blades .Known means of protection against cavitation damage in the form of pairs of edges that are installed in the zone of occurrence of cavitation  or along the boundaries of the zone of cavitation destruction . However, given the operational data, the effectiveness of such solutions is not high enough, especially during turbine operation in modes different from the calculation.Known protection against cavitation damage in the form of a device for supplying air to the zone of cavitation. Impeller radial-axial turbines with a device containing intake channel passing through the shaft, the manifold on the wheel hub and sauasage of the invention . In this known wheel cavitation erosion is most significantly decreased in area, located directly applied by means of the input air flow part, and in areas downstream, reducing erosion was observed to a lesser extent  . The last is particularly adversely manifests itself when the turbine at higher or lower pressures.The present invention is the task of creating the impeller radial-axial turbines with a device for supplying air in a flow path, which would be significantly more active than the known impellers, the effect on the cavitation process, suppressing them when the modes of operation of the turbine, which differs from the calculation.This problem is solved in the impeller radial-axial turbines, which contains the air intake channel, passing through the shaft, the manifold on the wheel hub and United with him means input air flow part on each blade and in which, in accordance with the invention, the input means of the air on each blade made in the form of hollow ribs extending from the inlet edges of the blades in the direction lineatella input edge of the blade, performed at least one opening for release of the air flow part. When this hollow edge on each blade is located with its front edge at the same distance from the hub of 0.2 - 0.8 times the length of the projection of the input edge of the blade to the axis of the impeller, and the length of each hollow rib is 0.05 to 0.2 from the nominal diameter of the impeller.This decision created and grounded in the three-dimensional mathematical modeling of current flow in radial-axial the impeller, which has allowed to establish that the modes of operation of the turbine, which differ from the estimates, the cavitation process intensifies additional vortex flow in the stream, which originates in the area of the inlet edges of the blades at the hub. At higher pressures this eddy current occurs on the back surface of the blade and extends along the inlet edges of the blades to the rim, then turns and runs along it, leading to additional pressure drop in the zones exposed to cavitation. When working at low pressures additional eddy current occurs on the working surface of the blades and extending from the hub to the rim, the implementation of the Asti, and then passes it to the output edge.To neutralize the negative impact of additional eddy currents was proposed to establish on the blades of the barrier ribs, preventing the passage of this vortex flow in the zone exposed to cavitation . Installing the separation of edges in the path of movement of the additional eddy currents, changing their trajectory, can significantly reduce cavitation erosion, which exposed the impellers when the turbines with large seasonal deviation of the head from the settlement. However, as shown by additional experimental study on cavitation stand, also known development zones of cavitation erosion, the installation of these barrier ribs in the form of a continuous vent any further development zone of cavitation erosion on the blades at the rear ends of these ribs.When performing in accordance with the present invention separation ribs hollow, the input of air flowing through them in part for the trailing edge of the ribs allows to eliminate the appearance of these additional development zones of cavitation erosion and even more to reduce erosion in known areas, typical modes of operation , the AK and ribs to reject the trajectory of the additional eddy currents generated by the input edges of the blades of the impeller. However, to achieve the effect ejection air supply hollow edge, according to the invention, should be set a little further from the hub.The essence of the present invention is illustrated following example, illustrated by the drawings, in which:
Fig.1 shows the impeller radial-axial turbines in longitudinal section;
Fig. 2 is a fragment of the blade at the location of the hollow ribs according to the invention, in section along a-a in Fig. 1 in an enlarged scale;
Fig. 3 - hollow edge, according to the invention, in cross-section B-B in Fig. 2
Impeller radial-axial turbines shown in the drawings, includes a wheel hub 1, the rim 2 and associated blade 3.To suppress cavitation impeller is equipped with an air supply system in flow part. This system includes the air intake channel 4, passing through the impeller shaft connected to the collector 5 for air distribution on the blades 3, United with him inlet tube 6, which the mouth of the input air according to the invention is made in the form of hollow ribs 8, located in the direction of flow of the main flow of water through the impeller on the current mode of operation and having in this direction streamlined hydrodynamic shape of the wing. On the rear edge of each rib is made a slot 9 for the release of the air flow part.The rib 8 for reliable shutoff and deflect additional eddy currents must have a length l of 0.05 - 0.2 of the diameter D1the impeller and the height of t within 0,010 - 0,012 D1. While the rib 8 on each blade 3 its front edge should be located directly behind the entrance edge of the blade and defend at a distance h from the hub 1 of 0.2 - 0.8 times the length of b0the projection of the input edge of the blade to the axis of the impeller. This arrangement of the ribs 8 is determined by the results of mathematical modeling conducted in connection with the problem of eliminating additional vortex motion, emerging from the inlet edges of the blades, and due to the need for safe ejection effect for air flow in the flow part.As it was previously installed on the edges with the corresponding functional purpose, they, with the forecast in the forecast mode of operation for seasonal low pressure should be placed on the working surface of the blades.The invention was tested for two years on one of the HPP with radial-axial turbine is operated with a significant seasonal increase in pressure. Two blades of the impeller of this turbine D1= 4.1 m was installed hollow rib in the wing directly behind the entrance edge of the blade at a distance h from the hub, amounting to 0.72 of length b0the projection of the input edge of the blade to the axis of the impeller. The edge length l was equal to 0.05 D1and its height t was 0,01 D1. The results of the examination of these blades has shown:
to install the edge intensity of cavitation damage on the blades during operation of the turbine at higher pressures was Iv= 0,23 cm3per hour;
when applying only air the intensity of cavitation damage is Iv= 0,07 cm3per hour;
when installed on the blade edges with the air inlet of the cavitation damage is not detected.Sources of information
1. Hydropower and auxiliary equipment of hydropower plants, so 1. M., 1988, S. 35-36, figure 4.7.2. Hydropower and auxiliary equipment of hydropower plants, so 1. M., 1988, S. 40.6. Patent RF N 99.100253 from 11.01.99. Impeller radial-axial turbines, containing the intake channel passing through the shaft, the manifold on the wheel hub and United with him means input air flow part on each blade, characterized in that the input means of the air flow part made in the form of hollow ribs extending from the inlet edges of the blades in the direction of the line current flowing in part on the current mode of operation, and the rear edge of the fin is made of at least one opening for release of the air flow part, when this edge on each blade is located with its front edge at a distance from the hub, equal to 0.2 and 0.8 of the length of the projection of the input edge of the blade to the axis of the impeller, and its length is 0.05 to 0.2 from the nominal diameter of the impeller.
FIELD: mechanical engineering.
SUBSTANCE: invention relates to devices aimed at reduction of cavitation in hydraulic machines. Method precludes break of liquid flow at striking of liquid against parts of hydraulic machines by forming controllable flow in near the boundary areas of hydraulic machines and increasing kinetic energy owing to imparting rotating component to flow in direction of movement of pump impeller. Plasticity is imparted to liquid flow by delivering air in amount of 2-5% of amount of supplied water. Device to reduce cavitation includes section of hydraulic machine pipeline made straight and eccentrically narrowing with profiled resistance elements in form of fragments of Archimedean spiral installed on its walls along passage part with inclination in flow. Section is arranged before centrifugal pump. Ratio of larger diameter of pipeline section to its smaller diameter is 1.8-1.5, and ratio of length of section to larger diameter is 1.5-2.0. Section is furnished with cylindrical rarefaction chamber installed before pump and with device to feed air into rarefaction chamber.
EFFECT: provision of reduction of cavitation in hydraulic machines.
3 cl, 1 dwg
FIELD: machine building.
SUBSTANCE: device in curved hydraulic path 1 consists of bypass channels 2 in wall of path 1 for liquid supply from increased pressure area I to decreased pressure area II. Inlet holes of channels 2 are located in the section before the flow turn, and outlet ones are located after flow turn in cavitation zone. Arc-shaped element 4 made from plastic material is installed above outlet holes of channels 2. At least one hole into which ring of constant diameter can be installed can be made in element 4. Element 4 can be made from porous material.
EFFECT: enlarging functional capabilities of anticavitation device in curved hydraulic path, which operates effectively irrespective of the change in capacity.
4 cl, 3 dwg
FIELD: engines and pumps.
SUBSTANCE: invention relates to hydraulic machinery and may be used in suction tubes of radial-axial hydraulic turbines at hydroelectric power stations. Proposed device comprises nozzle 1 for fluid feed to suction tube 2 beyond outlet edge of wheel 3. Nozzle 1 is made in the wall of tube 2 beyond outlet edge of wheel 3 to communicate via, at least, one bypass line 4 with downstream tube section 2. Nozzle outflow face represents annular slit or holes on tube 2 that make skewed face of nozzle 1 and ledge on tube wall. Ledge edge nearby wheel 3 extends beyond ledge edge, further from wheel 3.
EFFECT: reduced flow pulsations, stable operation.
11 cl, 9 dwg
FIELD: machine building.
SUBSTANCE: device for improvement of operating stability of a radial-axial hydraulic turbine includes bypass channel 3 made along the axis of impeller 1 of radial-axial hydraulic turbine 2 and interconnected at the outlet with space after outlet section of blades 4 of impeller 1 of hydraulic turbine 2. Impeller 1 is equipped with axisymmetrical fairing 7 fixed on sleeve 5 of impeller 1 and located in the space behind trailing edges of blades 4 of impeller 1 coaxially to the latter and converging in the direction of suction pipe 6. Outlet section of fairing 7 is located in the zone of inlet section of pipe 6. Channel 3 is made in fairing 7 and interconnected with pipe 6 on its inlet side. On its outlet side channel 3 is interconnected with the space behind outlet section of blades 4 of impeller 1 of hydraulic turbine 2 through outlet channels 8 made in fairing 7 in radial direction.
EFFECT: reduction of intensity of flow pulsations in a flow part of a radial-axial hydraulic turbine in the zone after the impeller outlet section.
9 cl, 10 dwg
FIELD: machine building.
SUBSTANCE: invention relates to testing of high-speed bladed machines equipped with hydraulic brakes. Hydraulic brake control method consists in feeding into braking chamber of working medium consisting of water preliminary saturated with carbon dioxide. Water saturation with carbon dioxide is carried out during turbine testing at various speeds of rotation and various degrees of hydraulic brake loading.
EFFECT: higher reliability of hydraulic brake owing to creation of controlled cavitation on working surface of hydraulic brake disk.
1 cl, 1 dwg
FIELD: machine engineering.
SUBSTANCE: shaftless straight-flow hydraulic turbine includes an impeller, a rim enclosing the ends of impeller blades, a rotor of generator with poles comprising one unit with the rim, a generator stator, a seal on the two sides of the rim. The rim with the rotor and the generator stator are enclosed in a chamber. The chamber has an inlet for compressed air supply with possibility of its feed adjustment, an inlet for pressure sensor in the chamber, a water flow pressure sensor located on the generator chamber. Ends of the rim are provided with circular concentric ridges. An air channel between the impeller rim and the turbine flow part is filled with porous material in form of cellular seals.
EFFECT: improved reliability of shaftless straight-flow hydraulic turbine design.
FIELD: turbine engineering.
SUBSTANCE: blade system comprises blades whose inlet and outlet edges are made so that the working section of the inlet blade edge adjacent to the hub prevents against cavitation.
EFFECT: enhanced efficiency and reliability.
2 cl, 5 dwg
FIELD: engines and pumps.
SUBSTANCE: hydraulic unit contains hydro generator, working blades rotating around a horizontal axis and having a shape formed with one parabola or with a cross of two parabolas, and a shaft running inside a bar to transfer a torque to the generator. The unit is equipped with a hollow drum with supports providing its floatation ability, and with a rotary table whereon the hydro generator is assembled. Also the hydro generator has inertial wheels with massive rims secured to both sides of the drum, and the second bar. The working blades are fastened flexibly with loops to the drum and pressed to the supports by flat springs. The shaft is made flexible and runs through both rods by means of which the axis of the unit is held and directed.
EFFECT: increased efficiency of a hydro unit.
FIELD: engines and pumps.
SUBSTANCE: centrifugal reaction impeller can be used in non-pressure devices, for example in centrifugal pumps and turbines. The impeller if made up of two plates with a circular belt rigidly fitted there between and furnished with closed discharge channels made therein. The aforesaid impeller is fitted on the shaft and has a hole to receive working medium. The discharge channels are arranged along the axial component perpendicular to the impeller radius, their outlets being directed towards the direction opposite to the impeller rotation. The impeller inner space features toroidal shape with a golden cross section.
EFFECT: reduced mechanical friction losses and higher efficiency.
FIELD: engines and pumps.
SUBSTANCE: invention is related to hydropower engineering, namely to design of turbine impellers. Tubular impeller comprises blades and shaft with upper and lower bearing disks. Tubular blades bent in the shape of elbow are installed between disks. Outlets of tubular blades are oriented horizontally along tangents to circumference of lower disk. Blades are arranged in the form of pipe sections, inlet upper sections of which are installed vertically. All pressure flow passes only inside tubular blades, which excludes non-power flow of water passing through turbine, improves cavitation characteristic of turbine and flow laminarity. External surfaces of tubular blades and surfaces of other impeller parts remain dry, which reduces losses for friction.
EFFECT: higher efficiency of impeller.