Thermodyanmics Question bank

ENGINEERING THERMODYNAMICS

                                                                       UNIT  5      PSYCHROMETRY

                                                                      PROBLEMS

Simple Problems

1)      What is the lowest  temperature that air can attain in an evaporate cooler ,if it enter

at  1 atm, 302 k, and  40% relative humidity?

2)      Consider a room that contains air at 1 atm, 308k, and 40% relative humidity. Using the

Psychrometric chart , determine the  specific humidity, the enthalpy, the wet bulb temperature,

The dew point temperature and the specific volume of the air.

3)      Atmospheric air at 1.0132 bar has a DBT of 32®C and a WBT of 25®C. compute (1) The partial

Pressure of water vapour, (2) The specific humidity, (3) the dew point temperature 

(4) the relative humidity ,(5) the degree of saturation, (6) the density of air in the mixture,

(7) the density of vapour in the mixture and (8) the enthalpy of the mixture.

       4)   In a laboratory test a sling psychrometer recorded dry bulb and wet bulb temperatures are

              303K and 298 k respectively. Calculate (1) vapour pressure (2) relative humidity (3) specific

              humidity (4) degree of saturation (5) dew point temperature (6) enthalpy of mixture

5)  A room 7m × 4m × 4m is occupied by an air water vapour mixture at 38°C. The atmospheric pressure is  1bar and the relative humidity is 70%. Determine humidity ratio, dew point temperature, mass of dry air and mass of water vapour. If the mixture of air –water vapour is further cooled at constant pressure until the temperature is 10°C. Find the amount of water vapour condensed.

Adiabatic Mixing

6)    30 m³/min of moist air at 15®C DBT and 13®C WBT are mixed with  12m³/min of moist air  a25°C              DBT and 18°C WBT. Determine DBT and WBT of the mixture assuming  the barometricpressure is  1 atm.

7)   Air at 20°C, 40% relative humidity is mixed adiabatically with air at 40°C, 40% RH in the ratio of                              1Kg  of former with 2 Kg of latter. Find the final condition( humidity and enthalpy ) of air.

8) A steam of air at 101.32 kpa, 18°C, and a relative humidity of 30% is flowing at a rate of               14.15m³/min. A second steam at 101.32 kpa, 38°C and a relative humidity of 50% is flowing at the rate of 8.5 m³/ min. The two streams are mixed adiabatically to form a third stream at 101.32 KPa. Determine the specific humidity, the relative humidity and the temperature of the third stream.

9) 1 kg of air at 313K dry bulb temperature and 50% relative humidity is mixed with 2 Kg of air at 293K DBT and 203K dew point temperature. Calculate the temperature and specific humidity of the mixture.

10)  Saturated air at 20°C at a rate of 1.167 m³/ sec is mixed adiabatically with the outside air at 35°C and 50% RH at a rate of 0.5 m³/ sec. Assuming adiabatic mixing condition at 1 atm, determine specific humidity , the relative humidity , DBT and volume flow rate of the mixture.

Psychometric Process Problem

11)An air conditioning system is to take in outdoor air at 283 k and 30% relative humidity at a

Steady rate of  45 m³/min and to condition it to 298 k and 60% relative humidity. The outdoor

air is first heated to 295 k in the heating section and then  humidified by the injection of hot

steam in the humidifying section. Assuming the entire process takes place at a pressure of 100 Kpa, determine  (1) the rate of heat supply in the heating section and  (2) the mass flow rate of the steam required in the humidifying section

12) Air at 16°C and 25% relative humidity passes through a heater and then through a humidifier to reach final DBT of 30°C and 50% relative humidity. Calculate the heat and moisture added to the air. What is the sensible heat factor?

                                                     THEORY PART

1)      Differentiate between

a)      Dry bulb temperature and Wet bulb temperature.

b)      Wet bulb depression and Dew point depression.

2)      In an adiabatic mixing of two streams , derive the relationship among the ratio of mass of streams, ratio of enthalpy change and ratio of specific humidity change.

3)      Show the following process on skeleton psychrometric chart

a)      Dehumidification and Cooling

b)      Heating and humidification.

4)      Describe the adiabatic cooling process and deduce the expression for its enthalpy.

5)      Draw the cooling and dehumidification process and explain sensible heat factor, Bypass factor and effectiveness of coil with respect to it.

Unit-IV (Big Questions)

1.Using the chaperon equation, estimate the value of the enthalpy of vaporization r-234a, 293k, and compare it with the tabulated value
2. Show that C_P-C_V=Ý for an ideal gas
3.  Show that the joule-Thomson coefficient of an ideal gas is zero (Or) Derive joule-Thomson coefficient of an ideal gas
4. Using the cycle relation and the first Maxwell relation, derive the other three Maxwell relations.

               (Or)Derive Maxwell relations.
5. Write a short note on generalized compressibility chart
6.  Derive wan der waal equation in terms of reduce parameter
7. Derive TdS equation taking temperature, volume and temperature, pressure as independent properties.
8. Prove that the total pressure is a sum of partial pressures
9.  A closed vessel has a capacity of  0.5m³ .l it contains 20% nitrogen and 20%oxygen 60% carbon dioxide by volume at 20%c and impa .Calculate the  equivalent molecular mass, gas constant, mass percentage and the mass of mixture
10.. A certain gas has C_p=0.913kj/kg and C_v=0.653kj/kgk. Find the molecular weight and the specific gas constant r of the gas

UNIT IV

1. What are the unique features of vanderwaal’s equation?

(i)                            Inter molecular attractive study is made.

(ii)                          Shape factor is considered.

(i)                            Inter molecular attractive study is made.

(iii)                        Shape factor is considered

(iv)                         

2. What is compressibility factor? What does it signify? What is its value for vanderwaal’s gas at critical point?

We know that, the perfect gas equation is PV=RT. But for real gas, a correction factor has to be introduced in the perfect gas equation to take into account the deviation of real gas from the perfect gas equation. This factor is known as compressibility factor (Z) and is defined by Z= PV/RT

At critical point, the vander waal’s equation                                    

                        P_CV_C/RT_C= 1 for ideal gases.

3. State Avogadro’s law and its significance.

Avogadro’s law states,” Equal volumes of different perfect gases at the same temperature and pressure, contain equal number of molecules”.

4. Write Maxwell’s equation.

(ðT/ðV) _s= - (ðP/ðS) _v

(ðT/ðP) _s= (ðV/ðS)_p

(ðP/ðT) _v= (ðS/ðV)_T

(ðV/ðT) _p= - (ðS/ðP)_T

5. What do you mean by equation of state?

PV=mRT is the equation of state which is obeyed by all ideal gases.

6. State Dalton’s law of partial pressure.

The total pressure of a mixture of gases is equal to sum of the partial pressure of individual gases if each gas exists in the total volume at mixture temperature.

P=P₁+P₂+P₃+…………+P_K

P=Total pressure

P₁&P₂,……… P_N= Partial pressure of each gas

7. Have you ever encountered ideal gas? If so where?

No. There is no ideal gas which obeys equation of state strictly. But gases can behave almost as ideal gases when they are in low densities and high temperatures.

8. What is meant by coefficient of expansion?

It is defined as the ratio between changes in volume to change in temperature per unit volume when the pressure is kept constant.

9. Explain (a) mass fraction & (b) mole fraction.

(a) Mass fraction:

             X_i=m_i = Mass of individual gas component

                   M_i    Mass of gaseous mixture

(b) Mole fraction:

             Y_i=N_i = No.Of moles of individual gas component

                   N     No. of moles of gaseous mixture

10. What does joule Thomson coefficient represent?

µ = (ðT/ðP) _h

Joule Thomson coefficient=   change in temperature         

                                                     Change in pressure                 when enthalpy is constant

11. What is meant by virtual expansion?

Viral or virtual expansions are only applicable to gases of low and medium densities.

The equation state of a substance is given by

P= RT + a (T) + b (T) + c (T) + d (T)

      V        v²        v³          v⁴         v⁵

       The coefficient of a(T),b(T),c(T),d(T)… are virial coefficients. The virial coefficient will vanish when the pressure becomes zero. Finally, the equation of state reduces to the ideal gas equation.

12. Difference between ideal gas and real gas.

An ideal gas is one which strictly follows the gas laws under all conditions of temperature and pressure.

In actual practice, there is no real gas which strictly follows the gas laws over the entire range of temperature and pressure. However hydrogen, oxygen, nitrogen and air behave as an ideal gas under certain temperature and pressure limits.

13. State Boyle’s law:

Boyle’s law states that, “the volume of a given mass of a gas varies inversely as its absolute temperature, when the temperature remains constant”.

V α 1/ p

14. State Charles law:

Charles’s law states, “The volume of a given mass of a gas varies directly as its absolute temperature, when the pressure remains constant”.

V α T

15. State joule’s law:

Joule’s law states, “The internal energy of a given quantity of a gas depends only on the temperature”.

16. What is clausius clapeyron equation?

It gives the relationship between saturation pressure & saturation temperature, the enthalpy of vaporization and specific volume of two phases.

     dp   = h_fg

      dt      T_fg

UNIT V

1. What is difference between air conditioning and refrigeration?

            Refrigeration is the process of providing and maintaining the temperature in space below atmospheric temperature.

            Air conditioning is the process of supplying sufficient volume of clean air containing a specific amount of water vapour and maintaining the predetermined atmospheric condition with in a selected enclosure.

2. Define psychrometry.

            It is the study of behavior of moisture content in dry air.

3. Name some psychrometric processes.

Ø Sensible heating

Ø Sensible cooling

Ø Humidification

Ø Dehumidification

Ø Heating and humidification

Ø Cooling and dehumidification

Ø Heating and dehumidification

Ø Cooling and humidification

4. Define dry bulb temperature (DBT-t_d).

            Temperature measured by ordinary thermometer is known as dry bulb temperature.

5. Define wet bulb temperature (WBT-t_w).

            Temperature measured by a thermometer whose bulb is covered by wet cotton is known as wet bulb temperature.

6. Define dew point temperature (DPT- t_dp).

            The temperature at which the water vapour condenses as water in atmospheric air is known as dew point temperature.

7. Define relative humidity and specific humidity.

            Relative humidity is defied as the ratio of mass of water vapour in the given volume of air at given temperature to mass of water vapour in the same volume of air at same temperature when the air is saturated.          

Φ = mass of water vapour in the given volume of air at given temperature

       mass of water vapour in the same volume of air at same temperature when the         air is saturated

                Mass of water vapour present in 1kg of dry air is known as specific humidity.

            w= mass of water vapour in the given volume of air at given temperature

                        Mass of same volume of air at same temperature

8. Define degree of saturation.

            Degree of saturation is the ratio of specific humidity of dry air to the specific humidity of saturated air of same mass.

            µ= specific humidity of dry air

                 Specific humidity of saturated air of same mass.

9. How is dew point temperature related to dry bulb and wet bulb temperature?

                    For saturated air, the dry bulb, wet bulb and dew point temperature are all same.

10. Define Apparatus dew point (ADP) of cooling coil.

                    For dehumidification, the cooling coil is to be kept at a mean temperature which is below the dew point temperature (DPT) of the entering. This temperature of the coil is called ADP temperature.

11. Define bypass factor (BPF) of a coil.

                    The ratio of the amount of air which does not contact the cooling coil (amount of bypassing) to the amount of supply air is called BPF.

                    BPF = Amount of air bypassing the coil

                                    Total amount of air passed

                                                          

       

GDJP Question bank

UNIT -1

1.     Air is moving at velocity of 150m/s, 100kpa at 25c. calculate Mach no. and stagnation property?

2.     Air flows at velocity of 250m/s ,the temperature of air measured at point is 30c .the air pressure is 5 bar .determine Mach no and stagnation property.

3.     A reservoir whose temperature can vary wide range of temperature, receive air at constant pressure of 150kpa the air is expanded isentropically is an nozzle. The exist pressure of 111.5kpa .i)determine (without using gas tables) value of temperature ,maintain in an reservoir to produce following velocity at nozzle efficiency 100m/s ii)250m/s

4.     A jet fighter is flying at Mach no 2.5 It is absorbed directly overhead at a distance of 10km.calculate the stagnation properties and speed of jet?

5.     Pressure, temperature, Mach no at entry of flow passage are 2.45 bar, 26.5 c and 1.4 respectively. Exist Mach no 2.5 determine for adiabatic (Assume isentropic ) of perfect gas (GAMMA=1.3) ,R=0.469kj/kgk. Find i) stagnation temperature ,pressure ii) temperature and velocity  at exist iii) flow rate per square meter at inlet cross section

6.     Pressure ,temperature ,velocity of air at entry a passage of 3bar,280k,140m/sm and pressure velocity at exit of flow passage are 2bar,260k,250m/s. Area of cross section at entry 600cm².Determine an adiabatic i) TO  Max velocity ii) Area of cross section at exit iii) Max. flow rate Given (gamma=1.4,R=287j/Kgk)

7.     Air is displaced from reservoir at pₒ= 6.91bar,Tₒ=325c .through nozzle at exit pressure of 0.98 bar .The mass flow rate 3600kg/Hr determine for an isentropic flow i)area ,pressure velocity  at throat ii) area and Mach no at exit iii)max possible velocity.

8.     A CONICAL DIFFUSER HAS ENTRY AND exit diameter as 0.15mand 0.3 m respectively. The pressure ,temperature, velocity of air at entry are 0.96bar,340k,185m/s respectively .Determine)exit pressure,velocity ,fore exerted on the diffuser wall .
 (R= 287j/kgk, γ=1.4,Cp=1.005kj/kgk)

9.     A stagnation pressure of 3.34 bar and temperature 627c is flowing through CV. The exit pressure 1.04 bar determine velocity, temperature, density at exit .Also determine the above if divergence act as diffuser. Assume Isentropic flow at exit.

10.         Air at Pi=3bar,Ti=500k,closedwith velocity of200m/s in 30cm diameter duct. Calculate i) mass flow rate ,ii)stagnation temperature iii) Mach no. iv) Pₒ(stagnation pressure)

11.         AN aircraft fly at 800km/hr, at altitudeof10,000 m .The air is reversibly compressed in inlet diffuser .The Mach no at exit of diffuser is 0.36 determine i) entry Mach no. and velocity ii) velocity ,pressure ,temperature at diffuser exit

12.         A supersonic will tunnel is design for M=3, at test section air supply form reservoir is 4bar and 26c .Determine mass flow rate, area of test section .Assume throat is 0.09m2. Gamma=1.4,alsofind temperature density for throat

13.         A supersonic wind tunnel setting chamber expands through a nozzle  from pressure 10 bar -4bar in test section calculate the stagnation temperature to be maintained in chamber to obtain to velocity of 500m/s in test section

14.         An aircraft is flying at altitude of 12,000m P=0.193bar ,T=216.65k at Mach no ;0.82.The cross section area of inlet diffuser is 0.5m2 .determine mass of air entering per sec, speed of aircraft ,stagnation pressure and temperature diffuser entry.

UNIT – 2    FANNO FLOW AND RAYLEIGH FLOW

RAYLEIGH FLOW

1)     Air having a M=3 with total temp of 295°C and static pressure 0.5 bar flows through a constant duct area adiabatically to another section where M₂ =1.5. Determine the amount of heat transfer & change in stagnation pressure.

2)    Air enters a constant duct area at M₁=3, P₁=1 atm and T₁=300K. Inside the duct the heat added/unit mass is 3*10⁵J/Kg. Calculate flow properties.

3)    The pressure, temp, Mach no of air in a combustion chamber is 4bar, 100°C, 0.2 respectively. The stagnation temp ratio is 3.Calculate

i)                   Mach no, temp, pressure at exit

ii)                Stagnation pressure loss

iii)              Heat supplied per Kg of air

4)    The Mach number at the exit of the combustion chamber is 0.9.The ratio of stagnation temp at the exit to the entry is 3.74.The pressure and temp of the gas at the exit are 2.5bar and 1270K.Determine

i)                   Mach no, pressure, temp of gas at entry

ii)                Heat supplied per Kg of gas

iii)              Max heat that can be supplied

5)    The pressure, temp, mach no of the gas at exit are 2bar, 1200K, 0.7.The ratio of stagnation temp is 3.85.Calculate the following

i)                   Mach no, pressure, temp at entry

ii)                Heat supplied per Kg of gas

iii)              Max heat that can be supplied

iv)              Identify whether it is heating or cooling.

6)    A combustion chamber gas turbine receives air at 350K, 0.55bar& 75m/s. The  air fuel ratio is 29.Calorific value of the fuel is 41.87 MJ/Kg. Taking ϒ=1.4, R=0.287 KJ/Kg for gas. Determine the initial and final mach no, final pressure temp & velocity of gas. Also find percentage of stagnation pressure loss and max attainable stagnation temp.

FANNO FLOW

7)    Air at 120KN/m ² and 40°C flows through 200mm diameter pipe adiabatically, the upstream mach no is 2.5.Determine the max length and properties at exit. Also estimate the length of pipe & exit mach no is 1.8.Take f=0.01

8)    Air at P₁=3.4bar, T₁=35°C enters a circular duct at a mach no of 0.14, exit mach no is 0.6, coefficient of fiction 0.004, mass flow rate 8.2 Kg/s. Determine

i)                   Pressure, temp at exit

ii)                Diameter of the duct

iii)              Length of the duct

iv)              Stagnation pressure loss

9)    A circular duct passes 8.25Kg/s of air , the exit mach no of 0.5.The entrance pressure and temp are 8.5bar and 38°C respectively, coefficient of friction is 0.005. If the mach no at entry is 0.15.Determine the diameter of the duct, length of the duct, Pressure and temp at exit & stagnation pressure loss

10)           Air if flowing into an insulator duct with velocity 150m/s, the pressure & temp of 28bar &280°C.Find the temp at section the duct. Finally where the pressure is 15.7bar the duct diameter is 15cm and friction factor is 0.005.Also find distance between two section

11)           Air at inlet temp of 60°C flows with subsonic velocity through an insulator pipe having inside diameter of 50mm, length of 5m.The pressure at the exit of pipe is 101KPa.The flow is choked at the end , the friction factor 4f=0.005.Determine inlet mach no, mass flow rate and exit temp

12)           The friction factor for 50mm pipe diameter is 0.005m.At the end of inlet velocity is 70m/sec. The temperature and pressure of 80°C and 10 bar respectively. Find temp, mach no, pressure at exit of pipe. The length of pipe is 25m long. Also find max possible length.

13)           Air is flowing in an insulator duct with the friction coefficient 0.002. At the inlet the velocity is 130m/sec. The temp is 400K and pressure is 25KPa. The diameter of the duct is 16cm.find

i)                   The length of the pipe required which gives 20% loss in stagnation pressure

ii)                Find the properties of air at the section 3.5m from the inlet.

iii)              Find max length.

UNIT-3

SHOCKS

NORMAL SHOCKS:

CONSTANT DUCT AREA:

1.     The state of gas (ᵞ=1.3 & R=0.469 kj/kgk) upstream of a normal shock wave is given by the following data. M_x=2.5,P_x=2 bar and T_x=275 k. Calculate the Mach Number, Pressure, Temperature of gas downstream of the shock.

2.     Air flows adiabatically in a pipe, a normal shockwave is formed. The pressure and temperature of air before shock are 150 kN/m² and 25^oC. The is just after the normal shock is 350 kN/m². Calculate the following
a). Mach Number before shock
b). Mach Number, static and velocity of air after the shock wave
c). Increase in density of air
d). Loss of Stagnation Pressure
e). Change in entropy

3.     A pitot tube kept in a supersonic wind tunnel normally weather forms a low shock ahead of A. The static pressure upstream of shock is 16 kPa and pressure at mouth is 70 kPa. Estimate the Mach Number of tunnel with the stagnation pressure is 300^oC and calculate static temperature and total pressure of upstream and downstream.      

VARIABLE CROSS SECTION:

1.     The C-D nozzle is designed to expand an air from reservoir pressure is 700kPa and temperature is 5^oC. The Inlet Mach Number is 2. The nozzle throat area is 230cm².  A normal shock appears at a section where the area is 175cm². Find the exit pressure and temperature also find increase in entropy across the shock.

2.     When C-D nozzle is operated at off designed condition.  The normal shocks appears at section where cross section area is 18.75cm² in the diverging port and at inlet to the nozzle.  The stagnation state is given as 0.21 MPa and 36^oC.  The throat area is 12.5cm² and the exit area is 25cm².  Estimate the exit Mach Number, pressure, and loss in stagnation pressure for flow through nozzle.

3.     A C-D air nozzle has exit to throat area ratio is 3.  A normal shock appears at the divergent section where the existing area ratio is 2.2.  Find the mach number before and after shock.  The inlet stagnation properties are 500 kPa and 450K.  Find the properties air at exit and entropy increase across the shock.

4.     A C-D nozzle has an exit area to a throat area ratio is 2.5.  The total properties of air at inlet of 7 bar and 87^oC.  The throat area is 65cm².  Determine mach number, pressure, temperature and stagnation pressure at exit when a plain normal shock stands at a point where the mach number is 2.  Assume isentropic flow before and after shock.

5.     A C-D nozzle is designed to expand a from a reservoir in which the pressure is 800 kPa and temperature is 40^oC to give a mach number at exit of 2.5.  The throat area is 25cm².  Find 
a). Mass flow rate
b). Exit Area
c). When a normal shock appears at a section where the area is 40cm².  Determine pressure and temperature at exit.

OBLIQUE SHOCKS:

1.     An oblique shock wave occurs at the leading edge of a symmetric wedge.  Air has a mach number of 2.1 and deflection angle of 15^o.  Determine the following for strong and weak waves.
a). Wave angle
b). Density Ratio
c). Pressure Ratio
d). Temperature Ratio

2.     A jet of air approaches schematically mach number of 2.4 and  wave angle of 60^o.  Determine the following
a). Deflection angle
b). Pressure Ratio
c). Temperature Ratio

d). Final mach number

3.     An oblique shockwave at an angle of 30^o occurs at a leading edge of symmetrical wedge.  Air has mach number of 2.1 upstream and upstream temperature and pressure is 300K and 11 bar respectively. Determine the following. 
a). Downstream pressure
b). Downstream temperature, mach number
c). Wedge Angle.

4.     An air jet at mach number of 2.1 is isentropically deflected by 10^o in clockwise direction.  The initial pressure is 100 kN/m² and T_x=18^oC.  Determine final state of air.

FLOW THROUGH SUBSONIC DIFFUSER:

1.     A mach 2 air craft engine employs a subsonic inlet diffuser of area ratio 3.  The normal shock is formed just upstream of diffuser inlet.  The free stream conditions of upstream diffuser are P_o=0.1 bar and T_o=300K.  Determine
a). Mach number, pressure and temperature at the diffuser exit
b). Assume isentropic flow in diffuser downstream of shock

2.     An air plane having a diffuser design for subsonic fly has a normal shock attached to the edge of diffuser.  When the plane is flying at certain Mach number.  If at exit of diffuser the mach number is 0.3.  What must be the flight Mach number assume isentropic diffusion behind the shock. Area at inlet is 0.29m² and exit is 0.44m².

Unit 4

1.     The flight speed of a turbo jet is 800 km/hr at 10000m altitude, the density of the air at the altitude is 0.71 kg/m³. The drag force of the plane is 6.8 KN. The propulsive efficiency is 60%. Calculate the 1) SFC 2) air fuel ratio 3) Jet velocity. Assume the calorific value of fuel is 45000 Kj/Kg and the overall efficiency is 18%.

2.     A turbo jet has a speed of 750 Km/hr, while flying at an altitude of 10000m. The propulsive efficiency of the jet is 50%. The overall efficiency is 16%. The density of air at 10000m altitude is 0.176 Kg/m3. The drag in the plane Is 6250 N. The calorific value of the fuel is 48000 Kj/Kg. Find 1) absolute velocity of jet 2) power output of the unit in KW 3) Diameter of Jet.

3.     Diameter of air craft propeller is 4m. The speed ratio is 0.8 at the flight speed of 450 Km/hr, the ambient condition of the air at flight altitude are T= 256 K and P= 0.54 bar. Determine the propulsive efficiency, thrust and thrust power.

4.     The diameter of the propeller of the air craft is 2.5 m. If flies at the speed of 500 Km/hr at altitude of 8000m. For a flight to jet speed ratio of 0.75. Determine the 1) mass flow rate of air to the propeller 2) thrust produced 3) specific thrust 4) specific impulse 5) thrust power.

5.     A turbo jet propels an air craft at a speed of 900Km/hr while taking 3000Kg of air per minute. The isentropic enthalpy drop is 200 Kj/Kg and the nozzle efficiency is 90%. The fuel ratio is 85 and the combustion efficiency is 95%. The calorific value of fuel is 42000 Kj/Kg. calculate the propulsive power, thrust power, thermal efficiency, propulsive efficiency and overall efficiency.

6.     An air craft flies at 960 Km/hr. One of the turbo jet engine takes 40Kg/s of air and expands it with ambient pressure. The air fuel ratio is 50, the lower calorific value is 43 Mj/Kg for maximum thrust power. Determine 1) jet velocity 2) thrust 3) specific thrust 4) thrust power 5) TSFC 6) Propulsive, thermal and overall efficiency.

7.     An air craft flies at 1000 Km/hr. One of the turbo jet engine takes 40Kg/s of air and expands it with ambient pressure. The air fuel ratio is 50, the lower calorific value is 43 Mj/Kg for maximum thrust power. Determine 1) jet velocity 2) thrust 3) specific thrust 4) thrust power 5) TSFC 6) Propulsive, thermal and overall efficiency.

8.     The turbo engine takes 50 Kg/s of air and propels the air craft with uniform flight speed of 880 Km/hr, the isentropic enthalpy change in the nozzle is 188 Kj/Kg. The velocity coefficient is 0.96. The fuel to air ratio is 1.2%, combustion efficiency is 95%. Calorific value of fuel is 44000 Kj/Kg. Find 1) thermal efficiency 2) fuel flow in Kg/hr 3) propulsion efficiency 4) overall efficiency.

9.     A turbo jet air craft at 875 Km/hr at an altitude of 10000m above mean sea level. Calculate 1) air flow rate to engine 2) thrust 3) specific thrust 4) impulse thrust 5) thrust power 6) TSFC. Take the following data, diameter of air inlet section= 0.75m, diameter of jet pipe at exit= 0.5m, velocity of gases at exit of jet pipe= 500 m/s, pressure at exit of the pipe is 0.3 bar, air to fuel ratio = 40.