1. Water at a flow rate of = 0.25 kg/s is cooled from 70 C to 30 c by passing it through a thick-walled tube of internal diameter of Di =50 mm and an external diameter of D = 60 mm. Hot Water is cooled by blowing cold air at T? = 15 C in cross flow over the tube. Velocity of the air over the tube is 20 m/s. Evaluating the water properties at 325 K from Table A.6 and evaluating air properties at a film temperature of 300 K from Table A.4 for outside flow, answer the following questions: Assume the pipe is made out of stainless steel with thermal conductivity of 15W/m/k
(a) What is the Reynolds number of the internal flow? [1]
(b) Using Dittus_Boetler correlation (Eqn 8.60), compute the convective heat transfer coefficient for the internal flow [2]
(c) Using Churchill-Bernstein correlation, compute the convective heat transfer coefficient for the external flow [2]
(c) By doing an energy balance, compute the length of the tube [3]
(d) What is the total heat loss? [1]
In: Mechanical Engineering
In the discussion for fatigue up to this point we have talked about the damaging effect of the number of cycles of loading but we have not discussed about frequency (i.e. how often these loading cycles occur). Which class of materials do you think might be sensitive to the frequency of loading? Provide two physical mechanisms that may affect fatigue life (at least indirectly).
In: Mechanical Engineering
Describe all processes in Otto cycle and Diesel cycle and plot its P-v and T-s diagram respectively
In: Mechanical Engineering
1. How much energy(kJ) is required to vaporize 10 kg of water at 500 kPa?
2. What is the state of water of 150 deg Celcius and 415.7 kPa?
In: Mechanical Engineering
A 150-mm-wide polyamide F-1 flat belt is used to connect a 50-mm-diameter pulley to drive a larger pulley with an angular velocity ratio of 0.5. The center-to-center distance is 2.7 m. The angular speed of the small pulley is 1750 rev/min as it delivers 1.5 kW. The service is such that a service factor Ks of 1.25 is appropriate.
(a) Estimate the centrifugal tension Fc and the torque T.
(b) Estimate the allowable F1, F2, and Fi.
c) Check the friction developmen
In: Mechanical Engineering
An Inertial Measurement Unit (IMU) is an important sensor used in aerial robotics. A typical IMU will contain an accelerometer and a rate gyro. Which of the following information does a robot get from an IMU? (Select all that apply. Choose only quantities that are directly reported by the IMU. Do not include quantities that can be computed from the IMU measurements but cannot be obtained directly. Additional research to find information about IMUs is allowed and encouraged!)
In: Mechanical Engineering
Discuss the impact of contemporary robotics locally, regionally and globally
In: Mechanical Engineering
Calculate the expected life of N (# of cycles) in a compression spring with the specifications.
Material: 302 Stainless Steel
End type: closed
Overall Length: 2"
OD: 0.5"
ID: 0.406"
Wire Diameter: 0.047"
Wire Shape: Round
Compressed Lenght: 1.35"
Maximum Load: 3.8 lbs
Rate: 5.85 lbs/in
RoHS: Compliant
In: Mechanical Engineering
a.If you see a white, powdery deposit on a surface, what does it mean to the component?
b.Why does intergranular corrosion reduce the strength of a component and does this
affect airworthiness of an aircraft?
c.What are the problems to detect small, sub-laminar tears on a large aircraft?
In: Mechanical Engineering
a.What are the main types of corrosion concerning aircraft?
b.What is the main difference between corrosion in steel and aluminum?
c.Why is humidity critical for Filiform corrosion?
d.What is meant by stress corrosion and how does it manifest?
In: Mechanical Engineering
a ) The moment of inertia of a rigid body, of mass 40 kg, about an axis through a point at 0.5 m from the mass centre, is 110 kg.m2. What is the moment inertia of the same body about an axis, parallel to the first, at a distance 1.0 m from the mass centre?
[4 marks]
i) A metal hoop, with mass m concentrated along its rim, has radius r, and rolls on a fixed surface without slipping. It has angular velocity ??. What is its kinetic energy? [4 marks]
j) Can a particle (point mass) have angular momentum? Explain your answer.
In: Mechanical Engineering
A section of pipeline is being lowered from a vessel to the sea bed. Assuming that the section of pipe is vertical whilst it is being lowered, at what point in the process will the wave forces be maximum? You should illustrate your answer with a sketch and refer to equations to explain why the forces are at their maximum in this position
In: Mechanical Engineering
In regards to the subject of Vibrations: Equations of Motion may be formulated using Newton’s Second Law force and moment balance or Lagrange’s Equations. Briefly discuss how to decide which method to use.
In: Mechanical Engineering
Mechanical systems must usually operate over a range of conditions. Unfortu- nately, one or more resonance points may have to be passed through during sys- tem startup to operating state or during system shutdown. How can this type of transitory resonance problem be addressed? What analytical tools could you use to convince someone of your approach?
In: Mechanical Engineering
Briefly explain the steps, tools, and techniques that you would take to analytically investigate a vibrations problem.
In: Mechanical Engineering