An airplane of length 6 m and with the wings of width 2 m and flat surface is flying at a spee

step 1 Okay, so let us find the Reynolds number by the formula Re equal to rho times V times x over Mu.

An airplane of length 6 m and with the wings of width 2 m...

An airplane of length $6 \mathrm{~m}$ and with the wings of width $2 \mathrm{~m}$ and flat surface is flying at a speed of $100 \mathrm{~m} / \mathrm{s}$. Determine the friction drag on each wing. Assume the boundary layer is fully turbulent. The airplane flies at an altitude of $1.0 \mathrm{~km}$

Key Concepts

Friction Drag

Friction drag is the resistance force exerted by a fluid on a surface due to the viscosity of the fluid. It results from the frictional shear stresses acting along the surface and is a critical component of the overall aerodynamic drag experienced by bodies moving through a fluid.

Turbulent Boundary Layer

A turbulent boundary layer is a region close to a surface in which the flow exhibits chaotic fluctuations and mixing, resulting in increased momentum transfer and higher shear stress compared to a laminar boundary layer. This enhanced turbulence typically leads to a higher friction drag, and its behavior is significant when analyzing aerodynamic performance.

Reynolds Number

The Reynolds number is a dimensionless quantity that compares inertial forces to viscous forces in a fluid flow. It plays a fundamental role in determining the flow regime—whether it is laminar or turbulent—which in turn affects the magnitude of friction drag on a surface.

Skin Friction Coefficient

The skin friction coefficient is a dimensionless measure of the shear stress exerted by the fluid on a surface relative to the dynamic pressure. In turbulent flows, empirical relations are used to estimate this coefficient, and it is a key factor in calculating friction drag.

Dynamic Pressure and Drag Force Calculation

Dynamic pressure, defined as one-half the product of the fluid density and the square of the velocity, quantifies the kinetic energy per unit volume of the fluid. When multiplied by the skin friction coefficient and the wetted surface area, it yields the friction drag force, which is essential for evaluating aerodynamic performance.

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