FIELD OF INVENTION
The present invention relates to testing of hydro turbine models. More particularly, the invention relates to the testing of vertical axis Francis turbine models & Kaplan turbine models in specialized test rigs.
BACKGROUND & PRIOR ART OF THE INVENTION
In case of Francis & Kaplan turbines, guide vanes are provided to control the flow into the runner and hence, they are a set of movable row of blades with each guide vane moving about its axis from completely closed condition to maximum possible opening as per requirement of power generation. The guide vanes are moved by an elaborate mechanism known as guide apparatus. The function of guide apparatus is to ensure accurate and equal rotation of all guide vanes for the complete range of operation from fully close position to fully open position. Since every hydro turbine is designed afresh, a homologous model is manufactured and tested in specialized test rigs.
The present invention relates to assembly of the model guide apparatus such that the guide vanes are provided with certain geometrical features that allow each guide vane to be assembled with specially designed mating components in the guide apparatus in such a way that all guide vanes are automatically set at their desired angular location uniformly. Another advantage of the present invention is that there is

no chance of slipping of the guide vanes within the guide apparatus under the hydraulic forces induced by high pressure water flowing during testing.
Francis turbines are designed afresh for every hydro power plant owing to the uniqueness of every site in terms of the head, discharge & speed, more specifically specific speed which is a mathematical combination of these quantities. This calls for detailed experimental tests to be conducted on the new hydraulic design to ascertain its suitability and acceptance of it’s performance parameters. These tests are conducted on homologous small scale models in specialized Laboratories wherein homologous hydraulic conditions as existing at actual site are created and the small scale turbine made to operate under these conditions and performance parameters measured. A number of tests are performed on these models, viz. performance test, cavitation test, runaway speed, guide vane torque, axial thrust etc. For all these tests, the conventional practice is that all guide vanes are rotated by a common guide apparatus which consists of a series of link-lever mechanism. This calls for a time consuming task of assembling all the vane into the guide apparatus such that all glide vanes are assembled at precisely the same angular location uniformly. The present invention provides for an apparatus for setting of all guide vanes uniformly in the guide apparatus. Also, this invention prevents the misalignment of guide vanes during testing under the hydraulic forces generated by high pressure water.
OBJECTS OF THE INVENTION

The object of the invention is to provide an apparatus which allows all guide vanes in a Francis turbine model or Kaplan turbine model to be set such that the minimum opening between any two adjacent guide vanes is uniform for the entire set of guide vanes.
Another object of the invention is to prevent the misalignment of guide vanes during testing under the hydraulic forces generated by high pressure water.
Further object of the invention is to ensure that all the guide vanes are assembled such that the minimum opening between any two adjacent guide vanes is uniform for the entire set at all guide vane openings from fully closed condition to fully open condition.
SUMMARY OF THE INVENTION
For the purpose of controlling the discharge through a Francis or Kaplan turbine, movable guide vanes are provided at the inlet of the runner. These guide vanes can be rotated about their axes such that they allow different quantities of water per unit time at different openings and hence, can be used to regulate the power output from the turbine.
Since the design of hydro turbines changes for every project depending upon the hydraulic conditions of head, discharge and geography of the project site,

model tests are performed on scaled homologous models of turbines in specialized test rigs in order to validate the performance parameters of the turbine. These models are in similitude with the full scale turbine so that the model test results can be used to predict the hydraulic performance of the full scale turbine (Fig 1).
During the manufacture and assembly of such models, the setting of the guide vanes such that the desired minimum gap between adjacent guide vanes for a particular opening angle is to be achieved uniformly for the entire set of guide vanes. This requires very careful and time-consuming guide vane setting and assembly procedure, which is highly dependent on the skill of the workman performing this task. Conventionally, this process of guide vane setting is done manually by trial and error method. Also, another Problem with the present art is that the torque required to rotate the guide vanes about their axes is transmitted to each guide vane through guide vane levers which hold the guide vanes purely through frictional resistance, there is no positive locking between the guide vane levers and guide vanes due to which there is always a chance of misalignment of one or more guide vanes during testing due to the hydraulic forces generated by high pressure water flowing through the guide vanes (Fig. 2).
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1: Francis/Kaplan turbine model guide apparatus assembly.

Figure 2: Assembly of Guide Vane stem and Guide vane Lever (Prior Art).
Figure 3: Assembly of Apparatus (Present Art).
Figure 4: Components of Apparatus (present art).
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION
The present invention provides an assembly and arrangement for the setting & locking of guide vanes comprising of:
- Regulating ring
- Guide vanes levers
- Z-ring
- Top cover
- Guide vane
- Pivot ring,
as shown in Fig.1
The invention proposes an assembly and arrangement comprising of a precisely machined special flat (1) and precisely machined mating faces (2) on the top of guide vane stem.

During the design of the model, flat surfaces on the top of the guide vane stem are designed such that it is machined precisely during the machining of guide vane feather profile using automated machining processes like CNC machine. A special flat is designed such that it mates with the flat surfaces on top of the guide vane stem and is also assembled with the guide vane lever (3). The above system automatically sets the guide vanes at a particular angular location with respect to the guide vane lever, thereby allowing the designed minimum gap between adjacent guide vanes required for testing.
The advantage of this arrangement is that since four flat surfaces are mating with each other, there is no chance of slipping of misalignment of guide vanes due to the hydraulic forces generated by high pressure water flowing through the model during testing.

WE CLAIM
1. An arrangement for guiding vanes of Francis/Kaplan turbine in a model assembly
comprising,
a) Special flat (1),
b) Guide vane with flat mating faces (2) on trunnion,
c) Screws (4) for connecting special flat with guide vane,
d) Guide vane lever (3)
wherein, guide vane lever (3) and guide vane are positively locked with each other through the special flat.
2. A method of locking guide vane (2) to guide vane lever (3) through special flat (1),
fixing the special flat with the guide vane lever by screws (4), preventing chances of
slipping or misalignment of the guide vanes due to hydraulic force during testing.
3. The method as claimed in claim 2, wherein fixing the special flat with the guide vane lever by screws (4), so that all guide vanes are set at their desired angular location uniformly and automatically during assembly.