In the flow around a cylinder, boundary layer separation occurs due to (SELECT CORRECT ANSWER)

A boundary layer is

Two flows may be classified as having dynamic similarity if

8: There is a boundary between a system A with a low temperature TL = 25 C and another system B with a high temperature TH = 89 C. The surrounding of the two systems has an equilibrium temperature 15 C.
a: Schematically sketch the transfer diagrams of temperature, heat, entropy, and exergy across the boundary between A and B.
b: Calculate the entropy at B and the entropy generation if the entropy at A is 2.9 kJ/K.
c: Calculate the exergy at B and the exergy destruction during the process.

Air at 1 atm and 80 ºC is used for the fluidization of catalyst pellets in 2.5 mm diameter in a vertical cylindrical reactor. The density of the catalyst particles is 3000 kg/m³. The catalyst particles have a sphericity (Øs) of 0.8 and . What should be the minimum limit of the air velocity? Explain the reasons

b) If the air flow rate is 45000 kg/h and the operational air velocity is 1.5 Vt, what should be the reactor diameter? Viscosity of air is 2.1x10^-5 kg/m.s

A roller coaster starts from rest at A, rolls down the track to B, describes a circular loop of 12-m diameter, and travels up and down past point E. Assume that there is no energy loss due to friction. Given: h = 20 m. Shoe the free body diagrams at points B,D, and E. Determine the force exerted by his seat by a 80 kg rider at B and D and the minimum value of the radius of curvature at E if the roller coaster is not to leave the track at that point.

Write a report on the security threats faced by india

can you answer those question as a field service engineer for job interview

1-Please describe in detail your knowledge of electrical engineering?

2-Please describe in detail your knowledge of mechanical engineering?

3-Please describe in detail your knowledge of computer software?

4-What does customer service mean to you?

5-What interests you most about this position?

6-What are your career goals?

7-Why are you looking for another job?

8-What is your business travel tolerance?

9-What has been your business travel levels in your past opportunities?

Consider the vertical rear window of an automobile that has a thickness L= 9 mm and height H=0.5 m with heating wires that create uniform volumetric heating. The window interior is exposed to ambient air at 10°C and the window exterior to air at -10°C which moves in parallel flow over the surface with a velocity of 20 m/s. The surface temperature of the window exterior is 12°C. Find the volumetric heating rate necessary to keep the window interior at 16°C. What is the convective heat flux for the interior and exterior of the window?

A white van is parked in the sun. The direct irradiance (Gdir) from the sun is 1065 W/m² with an incidence angle of 20^o from perpendicular to the roof of the van (area 3 m x 1.8 m). The roof has an absorptivity of 0.9 to solar radiation and emissivity of 0.2 to the surroundings (which have an effective temperature of 25^oC). A gentle breeze of 25^oC air blows over the van, with a speed of 6 m/s along the length of the van roof (3 m).

Assuming the bottom side of the roof is well insulated, calculate:

a) The convective heat transfer coefficient for the top surface of the roof of the van, assuming it is an isothermal flat plate and using the properties of air at 25^oC.

b) The irradiance and the total radiative energy absorbed by the roof (assume Kirchoff's law applies for diffuse radiative transfer between the surroundings and the roof of the van).

c) The temperature of the roof of the van and its radiosity.

d) A supplier offers to apply a reflective coating that reduces the absorptivity at solar wavelengths to 0.7 but reduces the emissivity at ambient conditions to 0.05. Would you recommend this as a solution to reduce heat transfer to the van? Why or why not?

It is noteworthy that during a holiday trip, the water is discharged from a high tank with a 30 cm diameter plastic pipe into a stream in the valley, and the idea of generating power from this water comes to your mind. The bird flight from the reservoir stream is 100 m and the height difference between the free water surface and the stream in the tank is 75 m.
(a) Show the relationship between the water flow in the pipe and the power to be obtained for the power plant to be installed to obtain power from this source by drawing the flow-power graph.
(b) Calculate the required water flow to obtain the highest power.

              Engineering graphic.
1. A circle of 50 mm diameter is resting on HP on end A of it’s diameter AC
which is 30 degree inclined to HP and makes 45 degree inclination to VP. Draw its
projections

question : 1

While cores increase the cost of castings, they also provide a number of distinct advantages. The most significant is the ability to produce complex internal passages. They can also enable the production of difficult external features, such as undercuts, or allow the production of zero draft walls. Cores can reduce or eliminate additional machining, reduce the weight of a casting, and reduce or eliminate the need for multi-piece assembly. Answer the following questions about cores.

1. The cores themselves must be produced, and generally have to be removed from core boxes or molds. What geometric limitations might this impose? How might these limitations be overcome?

2. Cores must be positioned and supported within a mold. Discuss some of the limitations associated with core positioning and orientation. Consider the weight of a core, prevention of core fracture, minimization of core deflection, and possible buoyancy.

3. Because cores are internal to the casting, adequate venting is necessary to eliminate or minimize porosity problems. Discuss possible features to aid in venting.

4. How might core behavior vary with different materials being cast—steel versus aluminum, for example?

5. Discuss several of the reasons cores may be made from a different material than the molding material used in the primary mold.

6. Core removal is another design concern. Discuss how several different core making processes might perform in the area of removal. What are some ways to assist or facilitate core removal?

Evaluate the disadvantages of ceramic over metal when loaded under dynamic
loading.

A 50 cm *50 cm copper slab 6.25 mm thick has uniform temperature of 300°C. Its temperature is suddenly lowered to 36°C. (quenched in water) Take The conductivity k-370 W/mK, the density rho-9100 kg/m³, the specific heat c-0.38 K/kg°C, the convection coefficient h=90 W/m2C.

1- Calculate the surface area, As

a - 0.125 m2
b- 0.5125 m2
c- 0.25 m2
d- 0.5 m2

2. Calculate the volume,

a- 0.0015625 m3
b- 0.003205 m3
c- 0.00078125 m3
d- 0.03587 m3

3. Calculate the characteristic length, Lc

a- 0.0625 m
b- 0.3125 mm
c- 0.00625 m
d- 0.003125 m

4. Calculate the Biot number, Bi

a- 0.00125
b- 0.00074
c- 0.00152
d- 0.000760

5. Calculate the thermal diffusivity, a (alpha)

a- 0.000107 m2/s
b- 0.0000107 m2/s
c- 0.0107 m2/s
d- 0.00107 m2/s

6. Calculate the constant of time, t (tau)

a- 1200.7 s
b- 0.125 s
c- 240.14 s
d- 120.07 s

7. Calculate the time required for the plate to reach the temperature of t1

a- 1560s
b- 312 s
c- 156 s
d- 0.156s

8. Calculate the time required for the plate to reach the temperature of t2

a- 586.275 s
b- 5862.75 s
c- 1172.55 s
d- 0.586 s

9. Calculate the temperature at the surface at time 100s , Ts 2

a- 279 ْ C
b- 210 ْ C
c- 36 ْ C
d- 150.8 ْ C

10. Calculate the total energy transferred from this plate during the first 100s , Q

a- 806.204 kJ
b- 485.841 kJ
c- 1139.874 kJ
d- 1.426 kJ

Drag measurements were taken for a 5 cm diameter sphere in water at 20 °C to predict the drag force of a 1 m diameter balloon rising in air with standard temperature and pressure. Given kinematic viscosity of water (v) = 1.0 X 10^-6 m²/s and kinematic viscosity of air (v) = 1.46 X 10^-5 m²/s.

1. Perform the Buckingham Pi theorem to generate a relationship for F_D as a function of the independent variables. Assume the drag F_D is a function of diameter (d), velocity (V), fluid density (ρ) and kinematic viscosity (v)

2.Determine the sphere velocity if the balloon was rising at 3 m/s