LOW SPEED WIND TUNNEL

OUTLINE:•Project objective•Introduction•Types• Design•Working•Applications•Advantages•Disadvantages•Conclusion

PROJECT OBJECTIVE:

•To simulate the movement or air around objects.

•To calculate drag and lift forces and their coefficients, flow velocity, pressure distribution etc.

INTRODUCTION:

•A wind tunnel is a machine which can simulate themovement of air around an object.

•It helps to calculate the lift and drag forces and their Coefficients.

TYPES OF WIND TUNNEL:

WIND TUNNEL

BASED ON FLOW SPEED

BASED ON TYPE OF

LOOP

BASED ON FLOW SPEED

TRANSONIC WIND

TUNNEL

SUPERSONIC WIND

TUNNEL

HYPERSONIC WIND

TUNNEL

SUBSONIC WIND

TUNNEL

TRANSONIC WIND

TUNNEL • Velocity in

test section is upto 340m/s or Mach number of 1.

• Used in aircraft industry since most commercial aircraft operate in this regime.

SUPERSONIC WIND

TUNNEL• Velocity in

test section is upto Mach number of 5.

• Used to investigate the behavior of jet engines and military aircraft.

HYPERSONIC WIND

TUNNEL• Velocity in

test section ranges between Mach number 5 and 15.

• Used in rockets and space vehicles.

SUBSONIC WIND

TUNNEL• Velocity in

test section is about 315 m/s.

• Used commonly in aerospace and automotive Industry

BASEN ON TYPE OF LOOP

OPEN LOOP WIND

TUNNEL

CLOSED LOOP WIND

TUNNEL

OPEN LOOP1.This type of wind tunnel is open at both ends.2.The chances of dirt particles entering with air are more.3.Flow rate is not constant.4.These type of wind tunnels are less expensive.

CLOSED LOOP1.Outlet of wind tunnel is connected to inlet so the same air circulates in the system in a regulated way.2.The chances of dirt entering the system are very low.3.Flow rate is constant4.These type of wind tunnels are expensive.

DESIGN:

dydynamometer

pitot tube

HONEY COMB: Outside air enters through the vent.

CONTRACTION SECTION: The air moves from wider area into narrow area

TEST SECTION: It provides desirable flow condition and space for model testing or experiment, where the instrumentation are situated.

GUIDE VANES: To guide the flow through the turning duct, and reduce the extent of secondary flows.

DIFFUSER: A device to lower the air flow speed, consequently reduce the pressure loss due to friction.

WORKING:

BLOWER

HONEY COMB

CONTRACTION SECTION TEST SECTION

GUIDE VANES

DIFFUSER EXIT

CALCULATION OF PRESSURE:

•The velocity of flow in the test section is calculated by using a pitot tube which is connected to a manometer.

•It is calculated by using the formula 𝑉 = '√2 𝑤𝑔𝐿𝛾𝜌 ' √ 𝜌aWhere, γ = specific gravity of the flow ρw = density of the flow g = gravitational acceleration L = length of manometer flow (pressure difference) ρa = density of air

CALCULATION OF DRAG AND LIFT:

• The drag force is determined by using the formula DF= 0.5 CD ρA (sq.V)•The lift force is determined by using the formula: LF= 0.5 CL ρA V (sq.V)

Where, FD=drag force LF=lift force ρ=mass density of the flow A=reference area v=velocity of object CD=coefficient of drag CL=coefficient of lift

APPLICATIONS:•Aerospace: Wind tunnel is utilized to study aircrafts in free flight.

•Automotive: In the automotive industry, wind tunnels are used to study the effects of moving air on the drag forces and energy consumption of a vehicle moving on the road.

•Architecture: The structural stability of a tall/large building might be compromised if the forces of the wind arenot taken into consideration. Often, wind tunnels are used to test those structures on a scaled down model.

•Sporting goods: Several applications are found in field of sporting goods, from bicycles, through the design of swimming suites, game balls that are affected by wind.

ADVANTAGES:•Progressive designers and engineers understand that significant savings in cost of structure and cladding can be obtained by completing a wind tunnel test in the early stage of the design.•Wind tunnels are used to predict the amount of force generated by solid objects.

•This helps aerodynamicists choose the proper size for things such as wings, spoilers, and parachutes.

•Information obtained in wind tunnels is used to improve the design of anything affected by wind.

•Accurate conditions required by the object is achieved.

DISADVANTAGES:•If located in a room, depends on the size of the tunnel to the room.

•For a given size and speed the tunnel will require more energy to run.

•It is noisy.

CONCLUSION:• By using this wind tunnel we can successfully study the movement of air around an object.

•The coefficients of drag and lift, velocity, pressure distribution can be calculated.

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