Skip to main content

Important Expressions used in Notches and Weirs

The following are the important expressions used in notches and weirs.
 
(a) Discharge over a rectangular notch or weir,


where
b = Width of notch or weir, and
H = Height of liquid above the sill of the notch.

(b) Discharge over a triangular notch or weir,



For a right angled V-notch, Theeta = 90°.

(c) Discharge over a trapezoidal notch or weir (also called Cippoletti weir) is equal to the sum of discharge over a rectangular notch or weir and the discharge over a triangular notch or weir.

(d) Discharge over a rectangular weir, according to Francis formula is given by



where
n = Number of end contractions.

(e) Maximum discharge over a broad crested weir,



Notes:
  1. A weir is said to be a broad crested weir, if the width of the crest of the weir is more than half the height of water above the weir crest.
  2. A weir is said to be a narrow crested weir, if the width of the crest of the weir is less than half the height of water above the weir crest.
  3. When the water level on the downstream side of a weir is above the top surface of a weir, then the weir is known as submerged or drowned weir.
  4. A weir, generally, used as a spillway of a dam is Ogee weir.
  5. It has been observed that whenever water is flowing over a rectangular weir, having no end contractions, the nappe (i.e., the sheet of water flowing over the weir) touches the side walls of the channel. After flowing over the weir, the nappe falls away from the weir, thus creating a space beneath the water. In such a case, some air is trapped beneath the weir.
  6. If the atmospheric pressure exists beneath the nappe, it is then known as free nappe.
  7. If the pressure below the nappe is negative, it is then called a depressed nappe.
  8. Sometimes, no air is left below the water and the nappe adheres or clings to the downstream side of the weir. Such a nappe is called clinging nappe or an adhering nappe.

Comments

Popular posts from this blog

Are Engineers Favourite Among Girls?

What do girls think about men who are engineers and what type of engineers are most favourite among girls? A survey was conducted by a team of aboutmech with members chosen from different countries. Each team member carried out a neutral survey in his/ her country to evaluate what females think about most of the engineers from different engineering branches. An overview of different questions asked in survey is given below: Question: Which male engineers do you find more attractive as a husband? Almost 50% women voted for mechanical engineers to be the most attractive husbands among other engineers. So mechanical engineers are most favourite among girls as a husband. They find them more trustworthy, intelligent, and creative. A married women from California said, “If your husband is a mechanical engineer, he will help you in everyday tasks. Because mechanical engineers are good team players and they have creative ideas about everything.” Which male engineers do you find more

Best CV Format for Mechanical Engineers

Fifty percent engineers fail to grab a dream job because of basic faults in their CVs/ Resume. This article tells you about best CV format for mechanical engineers and how you are supposed to design your CV when applying for jobs. You CV is your first impression on future employer. He/ she does not know you. Your CV is the only representation of your personality. He/ she may select or reject you after first glance on your resume.  I have experienced shortlisting and interviewing candidates for different jobs. I was astonished to learn that most of the candidates simply copy paste each others CVs without any changes at all. These types of CVs are rejected immediately. I am not trying to tell you that you should avoid copying, rather i ma telling you to refrain from giving your CV to your friends. An ideal CV consists of following portions: Name/ Address of the applicant Objective Education Record Employment History Professional Skills Awards & Achievements Co-Cu

Engineering Mechanics - Introduction

The Engineering Mechanics is that branch of Engineering-science which deals with the principles of mechanics along with their applications to engineering problems. It is sub-divided into the following two main groups: (a) Statics, and (b) Dynamics The Statics is that branch of Engineering Mechanics which deals with the forces and their effects, while acting upon the bodies at rest. The Dynamics is that branch of Engineering Mechanics which deals with the forces and their effects, while acting upon the bodies in motion. It is further sub-divided into the following two branches: (i) Kinetics, and (ii) Kinematics The Kinetics is that branch of Dynamics, which deals with the bodies in motion due to the application of forces. The Kinematics is that branch of Dynamics which deals with the bodies in motion without taking into account the forces which are responsible for the motion.