SU1564389A1 - Rig for testing pre-engaged axial wheels - Google Patents

Abstract

The invention relates to a testing technique and can be used in test equipment for upstream axle wheels separately without a centrifugal wheel. The purpose of the invention, the determination of wheel characteristics in advanced cavitation and supercavitation modes by determining the direction of the absolute flow velocity, is achieved by installing a test wheel in a cylindrical nozzle, behind which is a measuring section made in the form of a radial flat-blade flat diffuser, on the walls of which is perpendicular to the flow of the nut strings with flags. Flags have the ability to rotate about their axis of attachment. In addition, in the walls of the diffuser, in the installation area of the flags, there are windows with lighting devices, lenses and mirrors installed in them that are associated with the recording device. 4 il.

Description

The invention relates to a testing technique and can be used in test equipment for upstream axle wheels separately without a centrifugal wheel.

The purpose of the invention is to determine the characteristics of wheels in advanced cavitation and supercavitation modes by determining the direction of the absolute flow velocity.

Figure 1 shows the layout of the test bench for the pre-inclusion of the axial wheels in Figure 2, the dimensional section of the stand j in Figure 3. The experimental graphs of hydraulic losses .h. and angular corrections Dy (± in Fig. 4 is a scheme for determining the velocity of a fluid flow V in dimensional section 2 of an experimental pump.

The stand's hydraulic system contains a reservoir 1 with a working fluid, an underwater 2 and a pressure line 3, an electric drive 4 for driving the axial wheel 5 under test, which is located in the cylindrical nozzle 6 and the measuring section 7 (figure 1).

The measuring section 7 (Fig. 2) is made in the form of a radial bezlopatochny flat diffuser 8, on the walls of which the strings 9 with flags 10, which can be rotated relative to the axis of their attachment, are perpendicular to the flow. In the side wall of the diffuser 8 is made of windows 11 and-z proSP

O5 4

co oo co

opaque material with luminaires 12, lenses 13 and mirrors 14 installed in them for transmitting the image to the optical recording device 15. Flags 10 are separated from each other and separated from the walls of the diffuser 8 by bushings (not shown) that exclude direct contact and flagging when turning them on the string 9 under the action of fluid flow. The stand additionally contains an auxiliary circulating pump and a flow meter device.

The stand works as follows. The working fluid from tank 1 goes through supply 2 to a cylindrical tube 6 with an axial wheel 5 driven by electric drive 4. After the wheel 5, the fluid moves along a cylindrical annular channel 6, which passes into a radial belopostatochny flat diffuser channel 8. Thanks such an axial test wheel 5 is well adapted to work in a wide range of feeds V, and the flow of fluid in the measuring section behind the wheel 5 in the section of flags 10 is close to the plane-parallel and due to the increase in pressure in the diff sec tor channel beskavitatsion- Noe, even for highly developed cavitation in the axial wheel 5, including supercavitation modes. The flow cavity in front of and behind the wheel 5 is formed by interchangeable elements and its main dimensions may vary with respect to the dimensions of the axial wheels.

To determine the head of the axial wheel 5, the pressure P is measured and the average absolute velocity of the fluid V is calculated in measured sections in front of the wheel 5 and behind it.

Axial pump head

g 1

 + YjLI-Xl f g 2g

The pressure difference Pr - P, in measured sections, is determined by the readings of the pressure gauges or directly. differential pressure gauge. Hydraulic losses 2. h,. T between measuring sections 1 and 2 were estimated experimentally (Fig. 3) by pouring the flow cavity without a wheel 5 with the help of a circulation pump. There is an axial direction and an average speed before measuring section 5.

n

+ h1-t

0

with

s 35

®

45

50 55

0

Fluid V is determined from the flow equation:

V --- t

where D is the diameter of the inlet pipeline; V - fluid flow.

The angle of deflection of the flags 10 determines the direction of the absolute velocity Vt in dimensional section 2 (FIG. 4). Observations of the flags during pouring of the experienced axle wheel showed that under the force of gravity, the flags 10 deviate from the horizontal direction downwards by a certain angle D1, the value of which depends on the velocity of the liquid, i.e. from the feed V. The magnitude of the angular correction is taken into account by the experimental calibration graph (Fig. 3) when determining the direction of the velocity of the fluid V in dimensional section 2. In any operation modes of the axial wheel 5, all flags 10 are deflected by the flow at almost the same angle / °. This shows that in channel 8 with parallel walls in the section of measured section 2, the flow is close to plane-parallel and has a uniform velocity field, and hence pressure

For measuring, section 2 axle wheel 5

and

V co5 (about 0-DP

Whig AT)

where Vmg and Vu - average meridian

and the circumferential components of the absolute velocity of the fluid V in dimensional section 2,

about

Vm 2lrb where r is the distance from the axis of the wheel 5

to the measured section 2J b - the width of the flat diffusion

channel 8.

Based on the known measured head pressure H of the axle wheel 5 and theoretical head H ,. hydraulic efficiency and axial wheel 5 are determined

H

11 g and; The value of Nt is calculated from the hydraulic power Mg of the axle wheel 5, which is determined by the electric drive 4.

515

In a similar way, by the sign V ,, it is possible to determine on this stand other energy characteristics of the included axle wheel.

After the measuring section 7, the working fluid returns through the pressure line to the tank 1.

Such an embodiment of the test bench allows you to quickly and with sufficient accuracy determine the hydraulic characteristics and optimal operating modes of the upstream axial wheels of various types, including advanced cavitation and supercavitation modes.

Claims (1)

Invention Formula Test bench for pre-engined axle wheels, containing a container with working fluid, underwater and pressure J l 0 five 3496 motorway, located in the cylindrical tube of the test wheel and measuring section, characterized in that, in order to determine the characteristics of the wheel in advanced cavitation and supracavity modes, by determining the direction of the absolute flow velocity, the measuring section is made in the form of a radial infill-free flat diffuser, on the walls which the strings with flags are perpendicular to the flow of tension, having the possibility of rotation relative to the axis of their fastening, moreover, in the walls of the diffuser in the zone of and flags are made window defined therein lighting fixtures, lenses and mirrors, the latter being coupled to the recording device. AdL J / v-2 6 0 0.3 40 0.2 20. 0.1 01 Oh phegnae Fy fig.Z