BTEC Level 3 Unit 8 Mechanical Principles of Engineering Systems Assignment 03 Brief

Vocational Scenario or Context

Vocational Scenario

The use and application of mechanical systems is an essential part of modern life. The design, manufacture and maintenance of these systems is the concern of engineers and technicians who must be able to apply a blend of practical and theoretical knowledge to ensure that systems work safely and efficiently. The properties of a static liquid (hydrostatics) and a liquid in motion (hydrodynamics) underpin many aspects of engineering, and a sound understanding of these principles is essential for anyone seeking to become an engineer. You are working as a water systems engineer in a local company and need to solve the following problems. 

Task 1

For use in an irrigation system, you are required to design a tapered pipe to achieve an exit velocity (V2) of 6.4 m/s when water passes through the smallest diameter. The initial pipe diameter is 100 mm, and the input velocity (V1) is 1.6 m/s. No frictional losses are expected. 

• By considering the continuity of volumetric flow, calculate the required exit diameter for the pipe.
• The fluid used in the pipe is water that has a density of 1000kg/m³. Calculate the mass flow rate for the water in the pipe.

Task 2

Your line manager comes to work and mentions that they have just seen an article about minimising evaporation of (and photo-induced chemical reactions in) reservoir water. The article detailed the use of millions of plastic balls that float on the surface of water. Your manager wants you to investigate the optimum plastic and shape of a float that could be used. As a first step, you need to: 

• Explain Archimedes' Principle (you may wish to include some diagrams).
• For the next move in your research, you decide to study a simple shape for the plastic float. You consider a cube of plastic that has a side length of 6cm. Using Archimedes' Principle, calculate the upthrust force that would be experienced by a fully immersed cube of this size. 

Task 3

The company you work for is also looking into different designs of sluice gates for wastewater plants. The current design consists of a rectangular open channel that is closed by a hinged sluice gate at the end. When the water reaches a depth of 1.9 m, the sluice is forced open by the weight of the water, allowing it to flow into the lower channel. (Density of water is 1000 kg/m3). 

• Find the hydrostatic thrust acting on the sluice.
• By considering the position of the centre of pressure, calculate the hydrostatic turning moment acting on the sluice gate.

Task 4

• Compare the density results obtained from each method.
•  Discuss the advantages and disadvantages of each method for measuring the density of an irregularly-shaped object. 

Checklist of Evidence Required

Neatly written calculations showing all workings and units in standard form. 
State dimensions &/or values &/or scale on any drawings. 

Written explanations

Criteria Covered by this Task:

To achieve the criteria, you must show that you can: 

• Calculate the resultant thrust and overturning moment on a vertical rectangular retaining surface with one edge in the free surface of a liquid
• Explain Archimedes' Principle
• Use the continuity of volume and mass flow for an incompressible fluid to determine the design characteristics of a gradually tapering pipe
• Determine the upthrust on an immersed body
• Evaluate the methods that might be used to determine the density of an irregular-shaped solid material.