Mechanical Engineering Answers

A reheat cycle with two stages of reheating is executed, with steam expanding initially from 90 bar and 530 deg. C. The two reheater pressures are 10 bar and 0.6 bar, and the steam leaves each reheater at 480 deg. C. Condensation occurs at 0.03 bar. For an ideal cycle, find:

a. Q_a and e

b. For the engine, ignore the pressure drop through the reheaters, let the engine operate through the same states, and compute W and e.

c. What is the steam flow rate for an engine output of 20,000 kW?

A bronze tube, 60mm external diameter and 50mm bore, fits closely inside a steel tube of external diameter 100mm. When the assembly was at a uniform temperature of 15°C the bronze tube is a sliding fit inside the steel tube, that is the two tubes are free from stresses. The assembly is now heated to a uniform temperature of 115°C.

(a) Calculate the radial pressure induced between the mating surfaces and the thermal circumferential stresses, in magnitude and nature, induced at the inside and outside surfaces of each tube.

(b) Sketch the radial and circumferential stress distribution across the combined wall thickness of the assembly when the temperature is 115°C and insert the numerical values. [ E for steel = 200 GN/m² E for Bronze = 100 GN/m², poisson's ratio for steel = 0.3 poisson's for Bronze = 0.33, coefficient of linear expansion for steel = 12×10-⁶/°C and coefficient of linear expansion for Bronze = 19×10-⁶/°C]

(a) A steel tube is shrunk on to another steel tube to form a compound cylinder 60mm internal diameter, 180mm external diameter. The internal radial compressive stress at the 120mm common diameter is 30M N/m². Calculate the shrinkage allowance. E = 200 G N/m²

(b) If the compound cylinder is now subjected to an internal pressure of 25 M N/m². Calculate the resultant hoop stresses at the internal and external surfaces of the compound cylinder.

State & Explain the various criteria on which shaft are designed?

4. Two shafts A and B are connected by rolling cones and turn in the same direction. Shaft A makes 300 rpm while shaft B makes 100 rpm. Calculate the cone angle of each cone and the diameter of each base if the base of cone B is 2 in. from the vertex. θ = 30°

3. Two shafts, having axes in the same plate intersecting at an angle of 45°, turn in opposite senses at 30 rpm and 90 rpm. Draw a pair of cone to be located on these shafts and turn in pure rolling contact. Diameter of base of smaller cone is 1 in. Calculate the cone angles.

2. Two solids of right section 2 and 4 are in pure rolling contact between the circular arcs. What is the angular speed ratio for the position shown? Determine the size of the angles , β, and Ø in degrees, and of the radii x and y in inches.

A rain drop of mass 3gm starts to fall from rest under the effect of gravity from a height of

100m. There is an air drag acting on the rain drop, the drag force is given by the equation,

F = bv.

Here, b = 2 × 10−3kgs−1 s

(a) Determine the governing differential of the system.

(b) Build a SIMULINK model of the system using transfer functions.

(c) Show velocity vs time graph with and without the effect of air drag on the same

plot.

(d) Show height vs time graph with and without the effect of air drag on the same

plot.

(e) From your graphs, determine the approximate time required for the rain drop to

reach the ground.

Two shafts A and B are connected by rolling cones and turn in the same direction. Shaft A makes 300 rpm while shaft B makes 100 rpm. Calculate the cone angle of each cone and the diameter of each base if the base of cone B is 2 in. from the vertex. θ = 30°

Two shafts, having axes in the same plate intersecting at an angle of 45°, turn in opposite senses at 30 rpm and 90 rpm. Draw a pair of cone to be located on these shafts and turn in pure rolling contact. Diameter of base of smaller cone is 1 in. Calculate the cone angles.