The Free Air Jet Experiment

The Free Air Jet Experiment doorThe Free Air Jet Experiment is designed to give sharpness into the fundamentals of a free jet at various(a) locations wrong and outside the centerfield region. The core region is a location in the place of watercourse field where the campaign has a stop number that is approximately the very(prenominal) as the velocity coming from inside the jet. This experiment will come through data to describe the location of the core region. Besides defining the core region this experiment will provide information on the velocity changes outside the core region, atomic pile flow roams at various locations, the nervous impulse flow at various locations, showing that the progenying jet comprehensiveness varies with length, and how the zipper varies along the center streamline as a hunt down of keep from the exit.In order to best interpret the results obtained in this lab there are several(prenominal) assumptions that must be made. In this space t he flow is in a steady state, the air from the jet and the unmoving air in the surroundings is assumed to be constant, the flow is incompressible, and the produced flow is axis symmetric.The local fluid speed locoweed be heady from equation (1)V = (2*(po p)/)1/2 (1)where the vari subject V is the magnitude of the velocity, po is the stagnation military press, p is the static pressure of the fluid, and is the density of the fluid. From equation (2) the rush flow assess can be determinedmd = A (V)dA = 020R (Vr)drd (2)where md is the mass flow order, A is the surface area that is existence integrated over, is the density, r is the radius, and R is the maximum radius. The neural impulse flow can also be determined via equation (3)Pd = A (V)VdA = 020R (V2r)drd (3)where Pd is the momentum flow rate. The local last speed, c, was found from equation (4)c = (kRT)1/2 (4)where k and R are constants defined by the carnal properties of air and T is the temperature of the medium. I n this experiment k = 1.4, R = 287, and T = 298. Knowing c, the mach speed can be calculated via equation (5)Ma = V/c (5)where Ma is the mach speed.MethodsAn apparatus was constructed in such a way that a organ shout that emits air is placed naiantly and blows into a Pitot tube that can be moved crosswisely or in a radiate outer direction. The volumetric flow rate is a constant for this experiment. From here the first set of data to be record is the centerline speed of the jet at various even outdos aside from the center of the tube. This is first to be done by recording the pressure close to the pipes exit and and thusly taking pressure measurements increasing the distance from the Pitot tube to the pipes exit by small intervals. This will provide a relationship of mass flow rate and momentum flow to the distance from the air exiting the pipe. Change the volumetric flow rate and repeat the introductory procedure.To determine how the mass flow rate and momentum flow rat e will vary radially from the center streamline, another experiment is to be conducted. In this case a measurement is to be taken at the center streamline at some fixed swimming teddy with a constant volumetric flow rate. From here the Pitot tube is to be moved radially outward in small increments such that several data points can be obtained at that horizontal shifting. At a few other horizontal displacements the same procedure is to be followed.Results and wordFrom calculate 1 it can be seen that up to about 0.03 m from the exit, the centerline speed doesnt change much. This defines the core region starting from the exit of the tube to 0.03 m absent from the tubes exit. Outside the core region the speed of the air decreases as the distance from the exit is increased. When measuring the pressure from the Pitot tube the pressure had a precision of +/- 0.005 inches of H2O. This margin of error created an hesitancy in the centerline speed of about +/- 1 m/s. Knowing that the un certainty of the speed is about 1 m/s, this uncertainty will give out into the length of the core region. The core region can then be determined to have a length of 0.03 m +/- 0.01 m. Centerline speeds were preserve for a volumetric flow rate at 70 L/min and at 50 L/min. As expected, as the volumetric flow rate increases the centerline speed also increases.Velocities of varying radial distances from the centerline were careful and compared with each other at different horizontal distances from the tube in Figure 2. At a radial distance of 1 cm, the velocity doesnt change much with respect to the velocity measured at the centerline for all horizontal positions. This defines the average radial segment of the core region as 1 cm. This radial fragment decreases as a authority of the distance from the pipes exit. The farther the Pitot tube is moved outward from the core region the slower the velocity becomes. It can also be noticed that at the closest horizontal displacement the ve locity drops take quicker as a function of radial displacement as apposed to the larger horizontal displacements. This is caused by the energy dissipating out to the sides as the horizontal displacement increases. The energy dissipation is caused by eddies or to a greater extent(prenominal) usually swirling in air. An eddy is the terminology used to describe the circular exercise a fluid takes as it displaces from the source. This plays an even bigger role in mass and momentum flow rates.Looking at Figure 3 it can be seen that the mass flow rate increases as the horizontal displacement increases. This increase is caused by eddies. What happens here is the source puts out a finite amount of mass at some constant rate. Eddies then form and this swirling motion of the fluid reaches out into the stagnant fluid and pulls more mass in to the agreement. Now more mass is being brought into the clay causing the mass flow rate to increase. As the horizontal displacement increases the ma ss flow rate begins to level off, as seen in Figure 3, and will eventually begin to decrease. Here more mass is still being brought into the system but now the velocity has decreased importantly and this decrease is now causing the mass flow rate to decrease. besides to the mass flow rate the momentum flow rate is completed by eddies. In this case the momentum flow rate has reached a peak where the mass flow rate is still increasing and is decrease where the mass flow rate begins to reach a maximum, as seen in Figures 3 and 4. The momentum flow equation and mass flow rate equation only differ by one term. In the mass flow rate equation there is a V component and in the momentum flow equation there is a V2 component. Having this pointless component is what causes the momentum flow to peak before the mass flow rate. The velocity is decreasing and the mass is increasing as a function of horizontal displacement, but the momentum flow depends more heavily on the velocity component.The mach speed was then calculated from the maximum velocity obtained. In this situation the mach speed was found to be 0.087 with a local sound speed of 346 m/s. If the mach speed is greater than or equal to 0.3 than this implies that the flow is compressible. By having a mach speed that is smaller than 0.3 implies that the flow is incompressible.Conclusion and RecommendationsBy conducting this experiment a fairly accurate core region was able to be defined. The core region was defined as having a horizontal displacement of 0.03 m +/- 0.01m and an average radius of 0.01 m. The mass flow rate and momentum flow were both found to be heavily helpless on mass and velocity. Both the mass flow rate and the momentum flow were affected by eddies, which is the swirling motion of air, that pulled stagnant mass into the system causing the mass to increase as the flow got further away from the core region. The velocity of the air decreased as the displacement from the pipe exit increased. Moment um flow was affected by the velocity more so than the mass flow rate because of the V2 component in the momentum equation. This flow was deemed incompressible due to the mach speed being smaller than 0.3.For infract results in the future, supplying the jet with an independent compressor would eliminate any disagreement in volumetric flow rates caused by other users of the compressor. This would then generate a higher precision when measuring pressures.Figure 1. This chartical record shows the relationship between the centerline speed and the distance from the exit.Figure 2. This graph shows the relationship between the normalized velocity and the radial distance from the tubes exit.Figure 3. This graph shows the relationship between the calculated per measured mass flow rate and horizontal position.Figure 4. This graph shows the relationship between the rate of momentum flow and horizontal position.