GB/T 10969-2008Specification for water passage components of hydraulic turbines, storage pumps and pump-turbines (English PDF)

3.2 Unit

The international system of units (SI) and China statutory measurement units have been used throughout this standard.

4.1 General Provisions

A basic requirement for determining prototype performance is to have geometrical similarity between model and prototype.

Where the dimension tolerance of model meets the requirements of this standard, the measured average values may be replaced by the theoretical values.

Where the prototype is heterogenic to the model, an agreement shall be reached between the supplier and the purchaser whether the model efficiency is to be corrected or not through technology demonstration or individual test.

Water passage surface control dimension of water passage components shall not only meet the permissible tolerance specified in this standard, but also meet the structural coordination tolerance and the relevant requirements of GB 8564-2003.

possible to determine if the uniformity requirement has been met. If the uniformity requirement is not fulfilled, the corresponding components shall be corrected or remanufactured. In the case where the tolerance between the average value and the theoretical value is outside the permissible uniformity tolerance, the theoretical values or the geometrical dimensions of the components shall be corrected. Where spot-checks are performed for the recurrent components, the individual values may be directly compared with the theoretical values.

4.3.2 Checking the geometrical similarity between prototype and model

By comparing the corresponding average values of model and prototype and considering the permissible similarity tolerances as given by this standard, it can be determined whether the geometrical similarity requirement has been met.

If the geometrical tolerances are greater than the similarity tolerances, further steps shall be agreed by both parties.

For some dimensions which are difficult to measure on the model and/or prototype, the average values of model and/or prototype may be replaced by the theoretical values, provided that the total manufacturing and/or installation permissible tolerances is less than the permissible similarity tolerance.

4.4 Dimensional Check Procedures

4.4.1 Geometrical similarity check for model and prototype generally starts from the model

to check the geometrical similarity of prototype. Where the model is manufactured according to the existing prototype, the check starting point shall be the prototype.

4.4.2 Geometrical similarity check is composed of single check and post-assembly check.

As for the single check, the similarity of single component shall be checked. As for the post-assembly check, the similarity of the entire machine shall be checked. The runner axis and/or guide vane center line is usually used as the reference value for the relevant physical dimension of component assembly. Water passage formed by the transition between adjacent component, fixing and rotating parts shall be paid special attention to during the check.

Relevant permissible tolerances are not specified in this standard.

4.5 Dimensional Check Methods

To measure the shape (axial surface) of runner/impeller blades, guide vanes and stay vanes, several methods are suitable, including three dimensional co-ordinate measuring systems, optical measuring systems, templates, etc. Corresponding check for the blade shapes and geometrical positions of runner/impeller may be used for determining the blade setting angle.

Using three dimensional co-ordinate measuring systems or optical measuring systems, measurement can be made either by measuring points moving along curves or by measuring points on the surface. Where comparing the theoretical curve and the measuring results, the reference points may be adjusted so that the total measuring error is minimized.

Considering the manufacturing process of the runner/impeller, the supplier shall propose the most appropriate measuring method in agreement with the purchaser to demonstrate the geometrical similarity between prototype and model.

Figures 4 to 16 give examples showing schematically the location and extent of the dimensional check.

In some cases it is not possible to measure the relevant dimension directly (e.g. if a junction is covered by a round angle), the measurement shall be made in an agreed location.

In order to protect the confidentiality of the supplier's hydraulic design, the supplier need only submit the differences between the measured and the theoretical profile and not the actual values of the co-ordinates of the profile. For checking purposes, the absolute values and measured tolerances of inlet and outlet edge profiles may be provided by the supplier.

4.6 Multistage Machines, Seals and Thrust Balancing Provisions

4.6.1 Multistage machines

Normally the model test should be performed with the same number of stages as the prototype.

For a prototype with four or more stages, in exceptional cases, the model may be tested with a reduced number of stages (for instance a three-stage model test for a four-stage prototype).

4.6.2 Seals and thrust balancing provisions

For mechanical reasons, it may not be possible or desirable (especially for large scale ratios) for the shaft diameter, runner clearances and the thrust balancing provision to be either geometrically similar or hydraulically equivalent between the model and the prototype. In such cases, seal leakage losses and thrust coefficient will differ between model and prototype.

The differences shall either be negligible or be accurately estimated so that the hydraulic efficiency or the thrust of the prototype can be computed.

4.7 Dimensional Check Range of Water Passage Components

4.7.1 Reaction turbines

4.7.1.1 Main components

a) The principal dimensions of the spiral case (or diversion part in the case of a tubular turbine), the stay ring, the distributor, the draft tube, and if necessary the space between runner and head cover (see Figure 4, Figure 5, Figure 7 and Figure 8);

b) The principal dimensions of the runner including inlet and outlet diameters, inlet height, upper canopy and lower ring profile, and hub in case of axial flow and tubular turbine runner (see Figure 6 and Figure 9);

4.7.3 Storage pumps and pump-turbines

4.7.3.1 Main components

a) The principal dimensions of the spiral case, diffuser, suction pipe and if necessary the space between runner/impeller and head cover (see Figure 4, Figure 5, Figure 7 and

Figure 8);

b) The principal dimensions of the runner/impeller including inlet and outlet diameters, outlet height, and lower ring and upper canopy of runner/impeller (see Figure 9 and

Figure 12);

c) The number of runner/impeller blades, diffuser vanes/guide vanes and stay vanes;

d) The shape of the runner/impeller water passages, and shape of diffuser vanes/guide vanes and stay vanes (including the maximum thickness of stay vanes, diffuser vanes and runner/impeller blades);

e) Dimensions related to the sealing ring or end clearance of runner blade and end clearances of guide vanes (if any).

4.7.3.2 Centrifugal and radial flow runner/impeller

The requirements for centrifugal and radial flow runners/impellers are, for convenience, expressed in terms of a single-flow single-stage machine. For double-flow and multi-stage machines, additional measurements shall be taken of all inlets and stages.

a) Blade inlet profiles shall be measured at least at three sections. The length shall extend from the end of the blade to a distance of (0.1~0.15)1) D2 along the pressure side and suction side of the blade (see Figure 11);

b) The blade inlet angles shall be checked at the same sections as for inlet profile, and check template length shall not be less than (0.1~0.15)1) D2 (See Figure 11);

c) Blade outlet profiles shall be checked at least at two sections for low specific speed runners/impellers and at three sections for high specific speed runners/impellers. The length shall extend from the end of the blade to a distance of (0.1~0.15)1) D2 along the pressure side and suction side of the blade (see Figure 10 and Figure 11);

d) The blade outlet angles shall be checked at the same sections as for outlet profile, and check template length shall not be less than (0.1~0.15)1) D2;

e) Entire blade profile (from inlet edge to outlet edge) shall be measured at least for one section, if possible, depending on the specific speed or randomly on the whole surface

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