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416 results about "Specific speed" patented technology

Specific speed Nₛ, is used to characterize turbomachinery speed. Common commercial and industrial practices use dimensioned versions which are of equal utility. Specific speed is most commonly used in pump applications to define the suction specific speed —a quasi non-dimensional number that categorizes pump impellers as to their type and proportions. In Imperial units it is defined as the speed in revolutions per minute at which a geometrically similar impeller would operate if it were of such a size as to deliver one gallon per minute against one foot of hydraulic head. In metric units flow may be in l/s or m³/s and head in m, and care must be taken to state the units used.

Low-noise hydraulic design method of centrifugal pump with low specific speed

The invention discloses a low-noise design method of a centrifugal pump with low specific speed, and relates to an active control method of flow noise of turbomachinery. The design method comprises the steps that firstly, main structural dimensions of a centrifugal pump impeller and a helical pumping chamber (volute) are obtained by the traditional low-specific-speed pump design method; secondly, an internal flow field of the pump is computed by a computational fluid mechanics method; the performance of the pump is predicted whether to meet a design requirement; an optimum design improvement is performed by analyzing a stationary flow field; thirdly, flow induction noise of the pump with low specific speed is predicted by a computational acoustics method; if a flow noise index is qualified, the design is accomplished; if the flow noise index is disqualified, subsequent steps are performed; fourthly, the diameter of the impeller basically meeting a performance requirement in the design is adjusted to allow a gap between the impeller and a volute tongue to be increased continuously to 20%; splitter blades are added in the middles of blades to increase the lift, control the flow situation, and ensure the efficiency; and finally, the pump subjected to the impeller improvement design is subjected to noise prediction; if the flow noise index is qualified, the design is accomplished; and if the flow noise index is disqualified, the beginning step is repeated. The design method shortens the research and development period, saves the development cost, effectively improves the design quality of the centrifugal pump, can simultaneously meet low-noise requirements of the lift and the efficiency, and realizes optimization of the performance of the complete centrifugal pump with low specific speed.
Owner:JIANGSU UNIV

Unmanned surface vehicle trajectory tracking control device and method based on nonlinear control theory

The invention provides an under-actuated unmanned surface vehicle self-adaptive trajectory tracking control device and method. The device comprises a reference path generator, a state sensor, a differential converter, a parameter estimator, a virtual controller and a longitudinal thrust and bow steering torque controller. According to the unmanned surface vehicle actual position and course angle collected by the state sensor (2) and the reference position and reference course angle information generated by the reference path generator (1), the new state variable is obtained through the differential converter (5), the new state variable and the speed and angle speed information collected by a sensor (4) are transmitted to the parameter estimator (8) and the longitudinal thrust and bow steering torque controller (12), a control instruction is obtained through calculation to drive an execution mechanism, and the longitudinal thrust and bow steering torque of an unmanned surface vehicle are adjusted. According to the device and method, the unmanned surface vehicle can reach the specific position within specific time at specific speed. Due to the under-actuated unmanned surface vehicle, energy consumption and manufacturing cost of a system can be lowered, and the weight of the system is reduced.
Owner:精海智能装备有限公司

Method for hydraulically optimizing centrifugal pump under working conditions based on loss

The invention discloses a method for hydraulically optimizing a centrifugal pump under a plurality of working conditions based on loss, which comprises the following steps of: establishing a multi-working condition hydraulic optimization model of the centrifugal pump based on various loss formulae; establishing relationships among various loss coefficients, specific speeds and flows of the centrifugal pump at different specific speeds under the different working conditions by external characteristic experiments; compiling multi-working condition hydraulic optimization programs PCC.exe of the centrifugal pump by adopting Visual C++; integrating the PCC.exe by adopting iSIGHT, taking parameter values of single-point design as initial values, taking heads and power under the plurality of working conditions as constraint conditions, taking maximum efficiency under the plurality of working conditions as a target, and optimizing the centrifugal pump by adopting a global optimization algorithm or combination; and designing a multi-working condition hydraulic model by adopting PCAD according to an optimal solution set obtained in the optimization. The method has the advantages of not only performing multi-working condition hydraulic design on the centrifugal pump according to performance requirements under the plurality of working conditions, but also performing energy-saving alternation on the conventional centrifugal pump.
Owner:JIANGSU UNIV

Control method of low-speed stage starting of static frequency conversion starting of pumped storage power station

ActiveCN101621271ARealize frequency conversion startEasy to debugPolyphase induction motor starterFrequency changerLow speed
The invention relates to a control method of low-speed stage starting of static frequency conversion starting of a pumped storage power station, comprising the following steps: calculating the initial position of a rotor; estimating each force commutation moment of a low-speed stage inverting bridge according to a preset constant acceleration value; electrifying an appointed two-phase winding at the unlocking moment of a frequency converter according to an interval to which the initial position of the rotor belongs; switching a rectifier bridge to an inversion run mode at the forced commutation moment, sending a trigger pulse to a thyristor bridge arm corresponding to the appointed two-phase winding according to an interval to which a rotor position angle belongs at the moment after a loop of a frequency converter is cut out and each bridge arm of the inverting bridge is reliably shut off, and simultaneously switching the rectifier bridge to a rectifying run mode, and ending single forced commutation; ending the low-speed run stage if the rotor speed is higher than or equal to 5 percent of specific speed of a machine set, and then switching to a natural commutation stage based on machine terminal voltage, or carrying out the forced commutation again; and if starting exceeds time, regulating the preset constant acceleration value, and then restarting until successful starting. The invention can realize rapid and reliable frequency conversion starting at the low-speed stage of the machine set of the pumped storage power station as long as a set value of the constant acceleration of machine set starting is regulated.
Owner:STATE GRID ELECTRIC POWER RES INST +2

Multiple-working-condition hydraulic design method for guide vane type centrifugal pump

ActiveCN103939389AShorten the hydraulic design cycleMeet the design requirementsPump componentsPumpsGenetic algorithmEngineering
The invention discloses a multiple-working-condition hydraulic design method for a guide vane type centrifugal pump. The multiple-working-condition hydraulic design method for the guide vane type centrifugal pump mainly comprises the following steps that specific speed solution is conducted on the design working conditions of the guide vane type centrifugal pump, and the design working condition with the specific speed as an intermediate specific speed is selected and designed; multiple-scheme design is conducted on an impeller and guide vanes through an experiment design method, and the CFturbo style is adopted; mesh generation is conducted on a model, numerical simulation is conducted on a scheme through CFX, the lift and the efficiency value are read, and function fitting is conducted between the lift and a flow; function fitting is conducted between the lift and the flow of a design parameter point, the coefficient of a fitting function is used as a design goal, input main geometrical parameters are used as input values, an approximate response model is established through the Kriging model, rapid computation is conducted on the approximate response model through a multiple-target genetic algorithm, and then the optimal value is obtained. By the adoption of the multiple-working-condition hydraulic design method for the guide vane type centrifugal pump, the requirement for multiple-working-condition hydraulic design of the guide vane type centrifugal pump can be met; the multiple-working-condition hydraulic design method for the guide vane type centrifugal pump can also be used for multiple-working-condition hydraulic design of other guide vane type centrifugal pumps.
Owner:云南流体规划研究院有限公司

Predication method of complete characteristic curve of mixed-flow pump turbine

InactiveCN107191308AFull Characteristic Curve PredictionAccurate predictionHydro energy generationMachines/enginesOperating pointMixed flow
The invention discloses a predication method of the complete characteristic curve of a mixed-flow pump turbine. The predication method of the complete characteristic curve of the mixed-flow pump turbine comprises the steps that an internal characteristic analysis theory describing the flow complete characteristics and the moment complete characteristics are corrected through the feature of the actually measured pump turbine complete characteristic curve; statistics of unit parameters of feature operating points of the pump turbine complete characteristic curves of different specific speeds is conducted, the dominant function relationships between the unit parameter of each feature operating point and the optimal operating condition specific speed of the pump turbine and between the unit parameter of each feature operating point and the guide vane relative opening degree are established; and according to the dominant function relationships, the unit parameters of each feature operating point at different guide vane opening degrees are obtained, so that the undermined coefficient of the corrected internal characteristic analysis theory is determined, and a predicted complete characteristic curve of the pump turbine at any specific speed is obtained. The complete characteristic curve predicted by the adoption of the predication method is small in error, in this way, in a runner model simulation test, only a small number of feature working conditioner need to be tested, and the model test process is guided and accelerated.
Owner:CHINA INST OF WATER RESOURCES & HYDROPOWER RES

Ultra-low specific speed mixed-flow type turbine

InactiveCN101482083ASolve technical problems with low efficiency and complex structureHydro energy generationReaction enginesMixed flowHydraulic turbines
An ultra-low specific speed mixed-flow turbine relates to a mixed-flow turbine and belongs to the technical field of energy and power. A main shaft in the invention is arranged on a bearing support, and the bearing support is arranged in the middle of the upper side of a cover plate; the lower side of the cover plate is provided with the runner crown of a low specific speed turbine; the end of the cover plate is fixedly connected with a seating ring; the runner band of the low specific speed turbine is relatively arranged below the runner crown of the low specific speed turbine; one end of the runner band of the low specific speed turbine is connected with the seating ring, and the other end is connected with a conical draft tube; a metal scroll casing is connected outside the seating ring and is arranged on a rest pier; 16 to 18 single-row annular negative camber guide vanes are arranged on the seating ring, and the runner blades of the low specific speed turbine are arranged inside the inner cavity between the runner crown of the low specific speed turbine and the runner band of the low specific speed turbine. The invention solves the technical problem that low specific speed mixed-flow turbine has low efficiency and complicated structure in the prior art.
Owner:NANJING XINGFEI COOLING EQUIP

Hydraulic design method for low-specific-speed overload-free centrifugal pump impeller

The invention relates to a hydraulic design method for a low-specific-speed overload-free centrifugal pump impeller. Geometrical parameters of the low-specific-speed centrifugal pump impeller and performance parameters of a design condition point are related together through the method of setting up an equation, the optimal hydraulic performance and the good shaft power characteristic are obtained by adjusting values of the different geometrical parameters, and therefore the designed low-specific-speed centrifugal pump impeller can be free of humps and high in efficiency and can meet the overload-free requirement. A design formula of the main geometrical parameters of the impeller is given and includes the inlet diameter Dj of the impeller, the inlet diameter D1 of blades, the outlet diameter D2 of the impeller, the outlet width b2 of the blades, the number z of the blades, the inlet placing angle beta 1 of the blades, the outlet placing angle beta 2 of the blades, the wrap angle phi of the blades and the real thickness delta of the blades. By the adoption of the low-specific-speed centrifugal pump impeller, it can be ensured that a centrifugal pump can be used reliably under the high-lift and small-flow working conditions and used safely in an overload-free mode under the low-lift and large-flow working conditions.
Owner:南京通莱环保科技有限公司
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