Current Meter Support Frame Design
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Hatch is seeking a low-cost solution for hydroelectric turbine efficiency testing in order to win bids on project proposals. Presently, Hatch’s preferred method of performance testing for hydroelectric turbines requires custom manufacturing a large steel frame to secure flow meters. Custom designing frames is both time-consuming and expensive, making Hatch’s project bids more expensive than necessary. Hatch is seeking the design of an adjustable frame to secure their flow meters, allowing them to avoid custom designing and manufacturing individual frames and thus dramatically lowering the overall cost of turbine efficiency testing. To ensure our design aligns with the client’s vision, the client’s needs have been thoroughly considered. The design consists of two major assemblies, the current meter support frame and the hoist. The frame requires adjustability in both width and location of the flow measurement devices. The frame is also required to be supported by a hoist that is both relocatable and adjustable to match the adjustability of the frame. The hoist must be relocatable in that it is able to be disassembled and shipped between power generation stations in North America as well as easily transported while assembled at each generation station. Lastly, the hoist and frame must be able to be stored indoors and disassembled for shipping between different hydroelectric generating stations. The design must conform to several standards, including ISO 3354 [1], IEC 41 [2], and ASME PTC 18 [3]. Based on ISO 3354, in order to prevent inaccurate recordings in the flow measurement devices, the area of the frame must never surpass 6% of the unit intake area. The objectives of the report are to identify customer needs and perform rigorous mathematical calculations to support the design of a current meter frame and hoist. The design will include selecting a material, selecting a protective coating, and specifying required dimensions that ensure a useful life of 50 years is achieved. To perform this analysis, rigorous bending, weld, vortex, vibration, and bolt strength analysis have been used. The deliverables to the client include SolidWorks-based CAD files of the frame and hoist assemblies, a bill of materials for the list of materials and cost to produce the recommended design, all necessary calculations including both hand calculations and finite element analysis (FEA), engineering drawings, 48”x36” poster summarizing the final design, and a twenty-minute presentation summarizing the report’s analysis, findings, and final design. The final design for the current meter frame uses 6.675”x3/16” HSS circular tubing paired with 6”x3/16” HSS circular tubing and is able to achieve its modular requirement connecting various lengths of tubes via flange connections with three 3/8”-16 grade 5 nuts and corresponding 1” L bolts. The hoist follows a similar design to the current meter frame, using 4”x3/16” HSS square tubing paired with 3.5”x3/16” HSS square tubing, both with flanges in order to connect fixed-length sections. An extensive material analysis has been performed, and AISI 4130 steel was selected as the best option for material strength properties, cost, and availability. To prevent corrosion, a Macropoxy 646 coating has been recommended, which will prevent rusting and material deterioration over time. The final current meter and hoist design is capable of full functionality across a range of 2.1m to 7.0m wide intakes, covering approximately 80% of intakes expected to be bid on by Hatch based on past projects. Through the aforementioned detailed analysis, several factors of safety were calculated. The factors of safety for the current meter were found to be 2.4 due to bending, 1.13 due to yielding in the bolts, and 1.27 due to fatigue failure in the welds. The factor of safety for the hoist was calculated as 2.8 due to yielding stress. Lastly, the final weights were calculated to be 201 Kg and 285.8 Kg for the frame and hoist respectively.