Measuring Water Used In Turbine.
On May 10, 1911, Fire and Water Engineering contained a description of the transformer plant installed by the Pennsylvania Water and Power Company at McCall’s Ferry. Lancaster County, together with illustrations. Tests were recently given the hydraulic unit, in which temporary wooden flumes were built up in the intakes and the velocity of the water passing through four 6X16-6-ft. gates to the turbine was determined by pitot tubes. The general features of the development have been given from time to time in this and other journals, and some of the results of tests have been heretofore published.
A description of the hydraulic apparatus for the recent tests was printed in the General Electric Review, from whichthe following has been taken, and it was there stated that ’the wooden flumes were considered necessary in steady stream of water without eddies, the tlues conveying all the water without eddies, the flues cpnveying all the water supplied to ing fixed in the tapering intake chamber outside wooden headgates. The pitot tubes for measuring the velocity of the water in each chamber were supported on a steel frame which could be raised and lowered in front of the headgate Each frame consisted of a rectangular skeleton about 6×30 ft. in size made of channel iron and securely braced. Seven pairs of tubes were fixed to the bottom of the frame so that readings, could be had at seven points on a horizontal line across each opening. One of each pair of tubes had an open tip directed horizontally upstream, and the other had a closed, pointed tip also directed upstream and behind which were openings into the tube at right angles to the direction of flow. Each lube was connected to a 3-8-in. iron pipe, the pipes being carried up the framework and terminating in glass tithes on a gauge board to which connection was made by flexible rubber hose. Each gauge board was fixed to the movable steel framework which also supported a bench for the observer who was thus moved up or down as the position of the tubes was changed. The entire framework was suspended by steel ropes running over a pulley attached to the roof truss. The tops of the glass tubes were connected by rubber hose to a common header on a vacuum line, and by adjusting the vacuum the water columns could be maintained at a level convenient for reading. It should be noted that no zero level was used and only the velocity head was required which was given by the difference in the readings on each pair of tubes. Each glass tube was supplied with a cock at the top and bottom for isolating the water columns when a reading was being taken, as the height of the columns fluctuated continually. In the actual tests readings were taken on each gate at seven different levels in the incoming water, and in order to obtain a true mean velocity, three complete sets of readings were made on all of the tubes at each of these separate levels, thus for any given load on the machine practically 300 readings were necessary. which means about 1,200 readings for the four gauge boards. The object of the arrangement. as here described was to make it possible to get these 1,200 readings with the greatest practicable accuracy and rapidity. Having the velocity of the water, the input was readily calculated, and as the efficiency of the generators had previously been determined, the output of the turbine could also be ascertained. It should be noted that the hydraulic efficiency thus found was the hydraulic efficiency of the plant, as it was impossible to separate the efficiency of the approaches in order to arrive at the efficiency of the wheel itself.
Pittsburgh recently purchased three pieces of motor apparatus from different manufacturers which are now in that city. They were tested on the same day, the three cars working under same conditions, and after the test the car supplied by the American LaKrance Engine Co., was accepted by the city. The performance of this car under the serious conditions of the test demonstrated that it is a car of the highest type.