# 6MA041 Supersonic And Subsonic Aerodynamic – University

**Supersonic and Subsonic Aerodynamic**

**Learning Outcome 1: **Demonstrate a comprehensive understanding of key aerodynamic principles and their interaction with related engineering disciplines such as automotive and aerospace

**Learning Outcome 2: **Develop an understanding of the capability, scope and limitations of the different mathematical, experimental and computational tools that can be used in the aerodynamic field

**Learning Outcome 3: **Use fundamental mathematical, experimental and CAD methods to undertake aerodynamic design and analysis of key engineering structures.

**Learning Outcome 4: **Conduct appropriate research and investigations to generate innovative aerodynamic design for engineering vehicle and mechanical components with Improved aerodynamic efficiency.

**Assignment Brief**

Task Application of Bernoulli’s and Continuity Principles to flow along a convergent-divergent passage

In this task, you will conduct an experiment on the basic principles of airflow and aerodynamics using the AF10 Airflow Bench apparatus described in the experimental brief. The aims and objectives of the experiment are:

- To demonstrates the use of a Pitot-static tube,
- To investigate the application of Bernoulli’s theorem to flow along a convergent-divergent passage, and,
- To measure the distribution of total pressure P and static pressure p along the duct and compare the results with the predictions of Bernoulli’s equation. After conducting the experiment, you need to carry out the necessary analysis and answer the following questions.

(a) Plot the graphs of the total pressure P, the airbox pressure Po and the static pressure p on the y -axis against the whole length of the duct on the x-axis on a single graph. Choose appropriate scales for both the x and y axes with Correa label.

(b) Plot the graphs of the normalised velocity distribution, measured by the Pilot-static probe and the one inferred from the continuity equation on the y-axis against the whole length of the duct on the x-axis on a single graph. Choose appropriate scales for both the x and y axes with correct label.

(c) From the plots generated in (a) and (b), discuss your observations, the validation of Bernoulli’s and continuity concepts as well as suggestions for improving the experiment.

(d) Calculate the Mach number at the throat of the duct assuming that the static pressure and temperature at the throat are the same as in the airbox.

**Task: External flow around a wing**

A model wing that can be used for aerospace applications is placed in a test section of a wind tunnel where the pressure, temperature and Mach number of the flow are 1.03 bar, 300 K, and 0.2, respectively. The wing has NACA 0015 aerofoil and a chord length of 61.5 mm. The size of the computational domain is shown in Figure Q2, and the coordinates of the aerofoil surface are provided in Table 1.

(a) Using ANSYS-FLUENT, create a 2D – CFD model of the flow around the aerofoil. [20 %] Set up the simulations for a range of angle of attack (a), from 0° to 16°, with a step of 8° (i.e., 0°, 8°, 16°). Use Spalart-Allmaras viscous model for the flow using appropriate boundary conditions. Refine the mesh as appropriate, taking into account the boundary layer, leading edge, trailing edge and wake of the airfoil. Illustrate details of the steps taken to create this model, including geometry, mesh, boundary conditions, solver settings, and so on. Run the simulation for each angle of attack.

(b) Use the CFD simulation model and answer the following:

(i) Plot the curve of the lift coefficient against the angle of attack (CL vs a), the curve of the drag coefficient against the angle of attack (Co vs a), and the curve of the lift¬to-drag ratio against the angle of attack (CL /CD vs a). Critically discuss the results in terms of aerodynamic efficiency at varying angle of attack, and indicate the angle of attack at which the stall condition is reached.

(ii) Present the contour plots of velocity and pressure at 0°, 8° and 16° angles of attack, and qualitatively discuss the observed flow features.

(iii) Critically reflect on the accuracy of your results and suggest at least two ways to improve the results obtained from the CFD predictions.

(c) For the angle of attack of 8°, repeat the simulation for a Mach number of 1.6. Use appropriate plots and parameters to discuss the influence of Mach number on the aerodynamic behaviour of the wing and the flow patterns when compared with the solution obtained in Q2(a) above.

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