WO2001090537A1

WO2001090537A1 - Fish-friendly turbine

Info

Publication number: WO2001090537A1
Application number: PCT/US2001/016995
Authority: WO
Inventors: Thomas C. Cook; Apostolos K. Fetfatsidis; Philip S. Stacy
Original assignee: Ingersoll Rand Energy Systems Corp
Current assignee: Ingersoll Rand Co
Priority date: 2000-05-24
Filing date: 2001-05-24
Publication date: 2001-11-29
Anticipated expiration: 2002-11-24
Also published as: AU2001274968A1

Abstract

A runner (46) for a hydroturbine having a hub (54) and two or more turbine blades (50). The runner is characterized by a minimum pressure of 10 psia at the trailing edge (66) of the blades, a maximum velocity gradient of 15 ft/sec/in, and a maximum rate of pressure change of 80 psi/sec.

Description

FISH-FRIENDLY TURBINE

This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 60/206,774 filed May 24, 2000, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to a hydro turbine runner constructed to allow fish to pass through the runner without injury.

BACKGROUND PRIOR ART Attention is directed to U.S. Patent No. 5,997,242, covering a hydro turbine runner which has helical blades rigidly attached around a central hub, shaped to receive the mixed inflow and smoothly turn the flow to an axial direction at the turbine discharge. To avoid flow separation at the leading edge of the blades, which would be detrimental to safe fish passage and turbine (power) efficiency, the inflow characteristics conform to the leading blade angle (orientation) and curvature.

SUMMARY OF THE INVENTION The invention provides an improved runner for a hydro turbine, the runner including at least two turbine blades, the turbine blades each having a trailing edge. To provide for improved safe fish passage, the runner embodying the invention is constructed to provide a maximum rate of pressure change through the runner of 80 psi per second, a maximum velocity gradient through the runner of 15 feet per second per inch, and a minimum turbine pressure at the trailing edge of the turbine blade of 10 psia.

The invention further provides a new design for the region between a conventional scroll case and the hydro turbine runner. This region normally has many short wicket gates around the circumference of the runner. The new design expands this region to contain relatively few but unusually long wicket gates and a curved vaneless space downstream thereof to gradually turn the flow and produce an axial flow component into the runner. Inflow to the hydro turbine runner is based on continuity and conservation of angular momentum. For the design flow, the radial component of the velocity is known at any radius, r, for a given radial space width, b, and the tangential component of the velocity may be determined from rv=constant, where the tangential velocity component, v, is based on achieving the design head. These factors combine to produce a known absolute inflow angle to the runner. In practice, a scroll case will be needed to distribute flow uniformly around the runner entrance and wicket gates between the scroll case and Runner will be needed to regulate and shut off the flow. To provide the maximum practicable opening for safe fish passage, the gate opening at the best efficiency point (BEP) was set about equal to the gate height or radial space width, b. In conventional hydraulic turbines, the opening between the gates at the BEP is considerably smaller than the wicket gage height. For this new fish friendly turbine, the desire for large clearances resulted in relatively few, long gates and corresponding long parallel surfaces to form the radial space width (in the axial direction) to accommodate the gate rotation. Downstream of the gates, a gradually curved and vaneless downturn space is used to provide the desired mixed inflow to the Runner. This inflow reduces blade loading, flow separation and minimizes pressure changes with time, all favorable for safe fish passage.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an end view of a fish-friendly turbine embodying the present invention. Fig. 2 is a view taken along line 2-2 in Fig. 1. Fig. 3 is a side view of a two-blade ranner assembly. Fig. 4 is a perspective view of a three-blade runner assembly.

Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including" and "comprising" and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The use of "consisting of and variations thereof herein is meant to encompass only the items listed thereafter. The use of letters to identify elements of a method or process is simply for identification and is not meant to indicate that the elements should be performed in a particular order. DETAILED DESCRIPTION

This invention is an improvement of the invention disclosed in U.S. Patent No. 5,997,242. The entire contents of U.S. Patent No. 5,997,242 are incorporated herein by reference. Figs. 1 and 2 illustrate a fish-friendly turbine 10 that includes a scroll case 14 having an inlet 18. Water enters the scroll case 14 through the inlet 18 as shown by the arrow 22. The water flows through the scroll case 14 and into the a radial vaned space 26 through entrances 30. The water flows over vanes 34 within the radial vaned space 26 and enters a vaneless space 38 through another entrance 42. The vaneless space 38 is curved, and is used to provide the desired mixed inflow to the runner 46.

The water then enters a runner 46 of the turbine 10. Turbine blades 50 rotate within the runner 46 to move the water along, and a rotatable shroud 52 surrounds the blades 50. A hub 54 is positioned in the runner 46 and the water flows between the hub 54 and the rotating blades 50. The runner 46 includes a diameter 58 that is preferably 13 feet to reduce fabrication and installation costs and make the runner potentially viable as a replacement for existing hydroturbines. The water enters the runner 46 at the leading edge 62 of the blades 50 and exits the runner 46 at the trailing edge 66 of the blades 50. The water then flows into a draft tube 70 that preferably has an area ratio of 4:1.

The radial component of velocity of flow is known at any radius for a given radial space width. The tangential component of the velocity may be determined from the following equation: rv=constant. In this equation, r is the radius of the radial space, and v is the tangential component of the velocity. The radial and tangential components of velocity combine to produce a known absolute inflow angle to the runner 46. The scroll case 14 distributes flow uniformly around the runner entrance. Wicket gates are employed between the scroll case 14 and the runner 46 to regulate and shut off water flow. It is desirable to provide the maximum practicable opening for safe fish passage. To achieve this end, the gate opening is set at the best efficiency point. In this case, the best efficiency point is about equal to the gate height or radial space width. Conventional hydraulic turbines have relatively small openings between the gates at the best efficiency point. The present invention provides large clearances, which results in relatively few, long gates and corresponding long parallel surfaces. The long gates and long parallel surfaces define a radial space width (in the axial direction) that accommodates gate rotation. The illustrated turbine 10 has 75-85 feet of actual head across the runner 46, and permits 1000 cubic feet per second of water flow into the runner 46. The turbine substantially meets the following biological criteria that are favorable for safe fish passage through the runner 46: minimum pressure of 10 psia, maximum velocity gradient of 15 ft/sec/in, and maximum rate of pressure change of 80 psi/sec.

The runner 46 may include two or three blades 50, but the three-blade design has been found to perform better than the two-blade design with respect to the design parameters just listed. Fig. 3 illustrates a two-blade design and Fig. 4 illustrates a three- blade design.

Claims

1. A runner for a hydro turbine, the runner including at least two turbine blades, the turbine blades each having a trailing edge, the runner constructed to provide the following flow criteria: a maximum rate of pressure change through the runner of 80 psi per second; a maximum velocity gradient through the runner of 15 feet per second per inch; and a minimum turbine pressure at the trailing edge of the turbine blade of 10 psia.