Description
The strong pointsThis model is made up of: - a blower generating a laminar air flow, regulated and adjustable in speed (m.s -1) using 2 push buttons (+ and -), - a frame allowing isolation from external disturbances and limiting the noise generated, - a strain gauge sensor on which rests an object support allowing a very precise measurement of the drag force, the value of which is indicated on the display in mN. The display therefore makes it possible to read the 2 quantities (speed and force) in complete autonomy for manual data processing. To automate and simplify the processing of these data, the acquisition of the quantities can be done via the 2 analog outputs of the model connected to the voltmeter inputs of an ExAO console. A specific function of the model allows for this purpose to generate a speed ramp so as to automate the acquisition of values. Once the readings have been carried out and knowing the relationship between the drag force and the speed, it is possible to deduce the aerodynamic coefficient of each of the shapes. The quality of the sensor and that of the laminar flow generated allow the student to obtain a viable and reproducible scientific model whatever the shape of the object studied. 4 shapes are supplied with the model: 1 plane profile, a hollow ½ circular profile, a solid ½ circular profile and an airplane wing profile. These 4 shapes have the same master-couple (surface facing the direction of flow) so as to be able to have the students determine the aerodynamic coefficients in a real comparative approach, and to be able to make them classify these shapes. Note: the mock-up is calibrated without manual settings and in a few seconds when feeding the mock-up using the flat profile whose aerodynamic coefficient is equal to 1.