Chapter 2: Problem 92
How does an airplane wing develop lift?
/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none}
Learning Materials
Features
Discover
Chapter 2: Problem 92
How does an airplane wing develop lift?
All the tools & learning materials you need for study success - in one app.
Get started for free
Some experimental data for the viscosity of helium at 1 atm are $$\begin{array}{cccccc}\boldsymbol{T},^{\circ} \mathbf{C} & 0 & 100 & 200 & 300 & 400 \\ \boldsymbol{\mu}, \mathbf{N} \cdot \mathbf{s} / \mathbf{m}^{2}\left(\times \mathbf{1 0}^{5}\right) & 1.86 & 2.31 & 2.72 & 3.11 & 3.46 \end{array}$$ Using the approach described in Appendix A.3, correlate these data to the empirical Sutherland equation \\[\mu=\frac{b T^{1 / 2}}{1+S / T}\\] (where \(T\) is in kelvin) and obtain values for constants \(b\) and \(S\).
The flow field for an atmospheric flow is given by \\[\vec{V}=-\frac{M y}{2 \pi} \hat{i}+\frac{M x}{2 \pi}\\] where \(M=1 \mathrm{s}^{-1}\), and the \(x\) and \(y\) coordinates are the parallel to the local latitude and longitude. Plot the velocity magnitude along the \(x\) axis, along the \(y\) axis, and along the line \(y=x,\) and discuss the velocity direction with respect to these three axes. For each plot use a range \(x\) or \(y=0 \mathrm{km}\) to \(1 \mathrm{km}\). Find the equation for the streamlines and sketch several of them. What does this flow field model?
A viscous clutch is to be made from a pair of closely spaced parallel disks enclosing a thin layer of viscous liquid. Develop algebraic expressions for the torque and the power transmitted by the disk pair, in terms of liquid viscosity, \(\mu\) disk radius, \(R,\) disk spacing, \(a,\) and the angular speeds: \(\omega_{i}\) of the input disk and \(\omega_{o}\) of the output disk. Also develop expressions for the slip ratio, \(s=\Delta \omega / \omega_{i},\) in terms of \(\omega_{i}\) and the torque transmitted. Determine the efficiency, \(\eta,\) in terms of the slip ratio.
Streaklines are traced out by neutrally buoyant marker fluid injected into a flow ficld from a fixed point in space. A particle of the marker fluid that is at point \((x, y)\) at time \(t\) must have passed through the injection point \(\left(x_{0}, y_{0}\right)\) at some earlier instant \(t=\tau .\) The time history of a marker particle may be found by solving the pathline equations for the initial conditions that \(x=x_{0}, y=y_{0}\) when \(t=\tau .\) The present locations of particles on the streakline are obtained by setting \(\tau\) equal to values in the range \(0 \leq \tau \leq t\). Consider the flow ficld \(\vec{V}=a x(1+b t) \hat{i}+c y \hat{j},\) where \(a=c=1 \mathrm{s}^{-1}\) and \(b=0.2 \mathrm{s}^{-1}\). Coordinates are measured in meters. Plot the streakline that passes through the initial point \(\left(x_{0}, y_{0}\right)=(1,1),\) during the interval from \(t=0\) to \(t=3\) s. Compare with the streamline plotted through the same point at the instants \(t=0,1,\) and \(2 \mathrm{s}\).
A flow is described by velocity field \(\vec{V}=a x \hat{i}+b \hat{j},\) where \(a=1 / 5 \mathrm{s}^{-1}\) and \(b=1 \mathrm{m} / \mathrm{s}\). Coordinates are measured in meters. Obtain the equation for the streamline passing through point \((1,1) .\) At \(t=5 \mathrm{s}\), what are the coordinates of the particle that initially (at \(t=0\) ) passed through point (1,1)\(?\) What are its coordinates at \(t=10\) s? Plot the streamline and the initial, \(5 \mathrm{s}\), and 10 s positions of the particle. What conclusions can you draw about the pathline, streamline, and streakline for this flow?
What do you think about this solution?
We value your feedback to improve our textbook solutions.