Turbine blades mounted to a rotating disc in a gas turbine engine are exposed to a gas stream that is at tinfinity=1200 deg. c and maintains a convection coefficient of h=250w/m2k over the blade. the blades, which are fabricated from inconel, k=6*10-4 m2 and a perimeter of p=110mm. a proposed blade-cooling scheme, which involves routing air through the supporting disc, is able ot maintain the base of each blade at a temperature of tb=300 deg. c.

a. if the maximum allowable blade temperature is 1050 deg. c and the blade tip may be assumed to be adiabatic, is the proposed cooling scheme satisfactory?

b. for the proposed heating scheme, what is the rate at which heat is transferred from each blade to the coolant?

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.

Aloaded platform of total mass 500 kg is supported by a dashpot and by a set of springs of effective stiffness 72 kn/m. it is observed that when the platform is depressed through a distance x = 12.5 cm below its equilibrium position and then released without any initial velocity; it reaches its equilibrium position in the shortest possible time without overshoot. find the position and velocity of the loaded platform 0.10 sec. after its release. if a further load of 400 kg is added to the platform, find, i) the frequency of damped vibrations, and i) the amplitude of vibration after 2 complete oscillations, given that the initial amplitude is 15 cm.

The higher the astm grain-size number, the coarser the grain is. a)-true b)-false