Jawaharlal Nehru Technological University Hyderabad
Jawaharlal Nehru Technological University Hyderabad B.Tech III HYDRAULICS AND HYDRAULIC MACHINERY Previous Question Paper (July - 2021 - R18)
Answer any five questions. All questions carry equal marks.
Main
Derive an expression for the discharge through a channel by chezy’s formula.
Answer
Consider a uniform flow in an open channel. The forces acting on the fluid element are the component of weight in the direction of flow and the shear force at the boundary. For uniform flow, these forces are in equilibrium.
The force due to gravity in the direction of flow is given by:
The resisting shear force at the boundary is:
Equating these forces for uniform flow:
Since sin(θ) ≈ i (bed slope) and τ_0 = ρ g R i (where R = A/P is the hydraulic radius), we use the relation between shear stress and velocity: τ_0 = ρ g (v^2 / C^2). Substituting this into the equilibrium equation:
Simplifying for velocity v:
The discharge Q is the product of area and velocity:
Where C is the Chezy constant, A is the cross-sectional area, R is the hydraulic radius, and i is the bed slope.
Find the diameter of a circular sewer pipe which is laid at a slope of 1 in 8000 and carries a discharge of 800 liters/sec when flowing half full. Take the value of Manning’s N=0.020
Answer
Given: Discharge Q = 0.8 m³/s, Slope i = 1/8000 = 0.000125, Manning's N = 0.020. Since the pipe is flowing half-full, the area A = (π D^2) / 8 and the wetted perimeter P = (π D) / 2.
The hydraulic radius R = A / P = ((π D^2) / 8) / ((π D) / 2) = D / 4.
Manning's formula for velocity is:
Substituting Q = A * v:
Simplifying the constants:
The required diameter of the sewer pipe is approximately 1.485 meters.
Derive an expression for the depth of hydraulic jump in terms of upstream Froude number.
Answer
Sign in to view the complete answer paper.
The discharge through a rectangular channel of width 10m is 21 m3/s when depth of flow of water is 1.3 m. Calculate: i) Specific energy (E) ii) Critical depth (hc) and critical velocity (Vc) iii) Minimum specific energy (Emin).
Answer
Sign in to view the complete answer paper.
Define dimensional homogeneity and Explain Buckingham’s Theorem.
Answer
Sign in to view the complete answer paper.
Pressure drop ΔP depends on D, L, V, μ, ρ, k quantities. Find out the relation between these quantities using Buckingham’s π- theorem.
Answer
Sign in to view the complete answer paper.
What do you understand by characteristic curves of a turbine? Name the important types of characteristic curves.
Answer
Sign in to view the complete answer paper.
A Pelton wheel is to be designed for the following specifications: Shaft Power=11772 kW; Head=380 M, Speed=750 rpm, overall efficiency is 86%; jet diameter is not to exceed one-sixth of the wheel diameter. Determine i) Wheel diameter ii) number of jets iii) diameter of the jet.
Answer
Sign in to view the complete answer paper.
Explain about the classification of hydro power plants.
Answer
Sign in to view the complete answer paper.
A three-stage centrifugal pump has impeller 40 cm in diameter and 2.5 cm wide at outlet. The vanes are set back at the outlet at 30° and reduce the circumferential area by 15%. The manometric efficiency is 85% and overall efficiency is 75%. Determine the head generated by the pump when running at 1200 rpm and discharge is 0.06 m3/s. Find the shaft power also.
Answer
Sign in to view the complete answer paper.
Explain the terms: i) Distorted model ii) Undistorted model.
Answer
Sign in to view the complete answer paper.
Explain the following terms in detail: i) unit speed ii) unit power iii) unit discharge.
Answer
Sign in to view the complete answer paper.
Define a centrifugal pump. Explain the working of a single stage centrifugal pump with sketches.
Answer
Sign in to view the complete answer paper.
Explain the terms: i) rapidly varying flow ii) gradually varying flow.
Answer
Sign in to view the complete answer paper.
Explain the following terms:
Energy dissipation
Answer
Sign in to view the complete answer paper.
Positive and negative surges.
Answer
Sign in to view the complete answer paper.