Hydraulics Lab Report : Friction Losses in Pipes and Valves

Table of Contents

OBJECTIVES        

BACKGROUND THEORY (or INTRODUCTION)        

EQUIPMENT and COMPONENTS USED        

EXPERIMENTAL METHOD AND PROCEDURE        

Part 1        

Part 2        

OBSERVATIONS, DATA, FINDINGS and RESULTS        

Data discussion        

Graphs        

Error Analysis        

PROBLEMS/QUESTIONS        

RECOMMENDATIONS and CONCLUSIONS        

OBJECTIVES

The objective of this laboratory is to get familiarity with the concept of fluid flow in horizontal assemblies. It also involves analyzing concepts such as friction losses in pipes and valves and exploring flow measurement techniques.

BACKGROUND THEORY (or INTRODUCTION)

        In this laboratory, we used a fluid friction apparatus which is shown as a schematic in Figure 1 to measure the pressure drop experienced by the fluid using a piezometer. A piezometer is a type of manometer which measures the liquid pressure in a system by measuring the height to which a column of the liquid rises against gravity. The piezometer is especially suitable for measurement of low pressure changes and can be non-invasively connected to the fluid flow assembly. Clear tubing and pressure tapping points are used in the section across which the pressure needs to be measured. For measurement of higher pressure drops, a differential pressure gauge is employed.  

A volumetric hydraulic bench is provided along with the horizontal fluid flow assembly to facilitate the measurement of the volumetric flow rate of the water. The average flow rate can be measured by means of a collecting tank which collects the water and also has a volume indicator. A flow control valve controls the rate of flow of the water.

        Losses

EQUIPMENT and COMPONENTS USED

• Triaxial load cell
• Cylindrical specimens of Granite and Limestone for testing
• Computer with software

Figure 1: Cutaway illustration of a typical triaxial load cell

EXPERIMENTAL METHOD AND PROCEDURE

The following procedure is typically followed for a triaxial test:

1. The specimen is a cylindrical sample normally 100mm (4 in) in diameter by 200 mm(8 in) tall.
2. Specimen is enclosed vertically by a thin “rubber” membrane and on both ends by rigid surfaces
3. The sample is placed in a pressure chamber and a confining pressure is applied (σ3)
4.  The deviator stress is the axial stress applied by the testing apparatus (σ1) minus the confining stress (σ3). In other words, the deviator stress is the repeated stress applied to the sample. (Figure 2)
5. The resulting strains are calculated over a gauge length which is designated as L.
6. When the deviator stress is applied to the unloaded sample, the sample deforms changing its length as shown in Figure 3. This strain is directly proportional to the stiffness.

Figure 2: Stresses acting on a triaxial specimen

Theory

GSI: The Geological Strength Index (GSI) is a system of rock-mass characterization that has been developed in engineering rock mechanics to meet the need for reliable input data related to rock-mass proper-ties required as input for numerical analysis or closed form solutions for designing tunnels, slopes or foundations in rocks. The geological character of the rock material, together with the visual assessment of the mass it forms, is used as a direct input for the selection of parameters for the prediction of rock-mass strength and de-formability. This approach enables a rock mass to be considered as a mechanical continuum without losing the influence that geology has on its mechanical properties. It also provides a field method for characterizing difficult-to-describe rock masses.
The GSI system concentrates on the description of two factors, rock structure and block surface conditions. The guidelines given by the GSI system are for the estimation of the peak strength parameters of jointed rock masses.