Double-flow type volute casing having structure for changing direction of flow in turbine inlet
A double-flow type volute casing having a structure for changing the direction of flow in a turbine inlet is proposed. The volute casing includes a partition plate for partitioning a volute defined in the casing into an inner flow channel and an outer flow channel, provided so as to surround a turbine, a plurality of flow-rate adjustment holes formed in the partition plate so as to be arranged at a gradually decreasing interval such that a high-pressure fluid flowing in the outer flow channel is introduced into the inner flow channel and the fluid flowing in the inner flow channel is directed perpendicularly to the turbine blades, in order to minimize the amount of energy that is lost and to reduce imbalanced variation of torque applied to the turbine blades.
1. A double-flow volute casing having a structure for changing a direction of flow in a turbine inlet, the volute casing comprising:
a turbine disposed therein;
a volute inlet disposed in a vertical section of the volute casing;
a volute section disposed in a curved section of the volute casing;
an inner flow channel and an outer flow channel partitioned from each other through a partition plate so as to extend from the volute inlet to the volute section, wherein a ratio in a sectional area of the inner flow channel to the outer flow channel, the inner flow channel and the outer flow channel corresponding to the volute inlet and the volute section, is 4:6, and wherein a pressure of fluid flowing in the outer flow channel is greater than a pressure of fluid flowing in the inner flow channel and thus a flow rate in the outer flow channel is greater than a flow rate in the inner flow channel;
a partition plate disposed to extend from the volute inlet to the volute section;
a plurality of flow-rate adjustment holes disposed throughout a 180-degree section of the partition plate; and
a plurality of guide vanes for applying the pressure of the fluid to turbine blades, the plurality of guide vanes being disposed along a curvature of the partition plate at positions deviating from the 180-degree section of the partition plate in a rotational direction of the turbine so as to be spaced apart from each other by a predetermined distance,
wherein the pressure of the fluid in the outer flow channel is applied to the inner flow channel through the plurality of flow-rate adjustment holes,
wherein a ratio of the flow rate in the inner flow channel to the flow rate in the outer flow channel is 5:5 at an end point of the 180-degree section of the partition plate,
wherein diameters of the plurality of flow-rate adjustment holes are gradually increased as a flow speed of the fluid is increased in the volute section that is narrowed, and
wherein a flow rate corresponding to 10% of 100% of the fluid, introduced into the volute inlet, is equally divided and passes through the respective plurality of flow-rate adjustment holes.
2. The double-flow volute casing according to claim 1 , wherein each of the plurality of flow-rate adjustment holes is inclined in order to supply the fluid, introduced from the outer flow channel into the inner flow channel through the plurality of flow-rate adjustment holes, perpendicularly to the turbine blades that are located throughout the 180-degree section of the partition plate.
3. The double-flow volute casing according to claim 1 , wherein at least one of the plurality of flow-rate adjustment holes corresponds to at least one of the turbine blades that are located throughout the 180-degree section of the partition plate.