Method and device for determining hydralic pitch K value of propeller hydrodynamometer

Abstract

This invention relates to a method of determining blade hydraulic pitch value k of propeller flow meter containing separating the blade from the host to measure the blade mechanical pitch H by mechanism measurement and certificating value k of the sampled blade model with linear open channel and stable water to set up relationship of k=f(H) therefore to calculate k from measurement value H. The devices contain a drive shaft, outpt shaft, thread leading screw and adjustable speed drive. The drive shaft drives the output shaft and thread leading screw separately mounted with tested blades running along the trace of the standard mechanical pitch to get the value H with the differential method and trigonal principle.

Description

technical field [0001] The present invention relates to a method for determining the blade hydraulic pitch K value of a propeller current meter and its equipment, in particular to a method for measuring the blade hydraulic pitch of a general-purpose plastic blade propeller current meter widely used in river hydrological tests and the equipment used in this method. Background technique [0002] The paddle is used as the sensing element of the propeller current meter to measure the water flow velocity. The determination of its hydraulic pitch K value is usually matched with the main engine of the current meter to form a complete instrument. In the way of the whole machine, the hydraulic experiment method is used to determine the hydraulic pitch through indirect measurement. The method measures the motion parameters of the blade, and solves the motion equation of the blade by data processing according to a series of experimental data measured. Currently, all countries in the w...

AI Technical Summary

Problems solved by technology

Defects in the test method of straight line open channel: 1. The influence of waves makes the test results have false positives: During the test, when the current meter frequently moves relative to the still water, waves are aroused, causing accompanying currents, and resulting in flow velocity increments ± ΔV, which in turn acts on the instrument, affecting the normal operation of the blades, resulting in verification errors, and thus leading to false detection of verification results

4. Groove wall effect error

5. Low efficiency of verification work: In order to reduce and limit the influence of flow rate increment ±ΔV, the SL / T150-95 standard stipulates: at each flow rate level V i Before the driving test, there should be an appropriate still water time t i , when V=0.5, 2, 3m / s, t is 10, 15, 25min respectively, and there needs to be more than 12 hours of still water time before the low-speed verification; in order to reduce the random error caused by the influence of the increment ± ΔV, the measurement The number of points should not be less than 20

Therefore, the work efficiency of flow meter production verification is low

6. The operation procedure is complicated: the operation procedure of the instrument verification: the instrument is run from the assembly workshop to the verification tank, grouped and numbered, the instrument is installed, the direction of the instrument is calibrated and fixed, and the inspection is carried out according to the specified measuring point. Instrument, dry the water, dismantle and wash the internal parts of the instrument, refuel, transport back to the assembly workshop, etc.

The operating procedures are very complicated and labor-intensive, especially during the high-speed driving test, the workers are nervous; the data detection and calculation procedures in the test are also quite complicated, and the process is long; there are many staff

7. Large investment in verification equipment and high operating costs: The straight-line open channel verification equipment includes: straight-line open channel long water tank and its corresponding supporting plant infrastructure; verification vehicle and its running track; verification vehicle speed control system; detection data collection and its treatment system; water and electricity supply system; testing equipment maintenance workshop (including supporting staff)

The total investment is large, and the daily operation and maintenance costs are high

8. The maintenance cycle of the instrument is long: the hydrological survey station is located in a remote place, and the transportation is inconvenient. The maintenance instrument needs to be transported back and forth over a long distance, and the repaired instrument is damaged on the way and needs to be sent for inspection again. The whole maintenance process is very inconvenient. cycle is very long

Images