Angle of attack

Dynamic pressure may be measured by use of a pitot tube that is a simple impact tube. These tubes measure the pressure at a point where the velocity of the fluid is brought to zero. Pitot tubes must be parallel to the flow. The pitot tube is sensitive to yaw or angle attack. In general angles of attack over 10° should be avoided. In cases where the flow direction is unknown, it is recommended to use a Kiel probe. Figure 10-3 shows a Kiel probe. This probe will read accurately to an angle of about 22° with the flow. 

The pitot-static tube is also sensitive to yaw or angle of attack than is the simple pitot tube because of the sensitivity ofthe static taps to orientation. The error involved is strongly dependent upon the exac-t probe dimensions. In general, angles greater than 10° should be avoided if the velocity error is to be 1 percent or less. 

How these factors affect erosion can be determined from the empirical equation shown in Table 4-14. The equation shows erosion rate proportional to a constant, the mass of the particle, its velocity, and angle of attack. 

Two coefficients have been defined. Cl and Co, relating velocity, density, area, and lift or drag forces. These coefficients can be calculated from wind-tunnel tests and plotted as shown in Figure 7-6b versus the angle of attack... 

The net aerodynamic force exerted on a body is illustrated in Figure 2 by the arrow labeled R. The direction and speed of the airflow ahead of the body is denoted by V, called the relative wind. The body is inclined to V . by the angle of attack, a. The resultant aerodynamic force R can be resolved into two components lift, L, perpendicular to V. and drag, D, parallel to V,. In Figure 2, R is shown acting through a point one-quarter of the body length from the nose, the quarter-chord point. Beacuse the aerodynamic... 

At flow speeds well below the speed of sound, the lift coefficient depends only on the shape and orientation (angle of attack) of the body ... 

Optimizing the angles of attack strongly favours the stereochemistry predicted by Cram s rule compare the pairs of entries 1 and 2, 3 and 5, 6 and 7, 8 and 9. 

Electrophilic assistance reduces the values of the optimal angles of attack (entries 2 and 5, 7 and 9). 

Substrate Reagent Angle of attack Asymmetric induction ... 

For entries 2, 5, 7 and 9, the first (second) value refers to the optimized angle of attack in transition state 12 (resp. 13)... 

Special Tubes A variety of special forms of the pitot tube have been evolved. Folsom (loc. cit.) gives a description of many of these special types together with a comprehensive bibliography. Included are the impact tube for boundary-layer measurements and shielded total-pressure tubes. The latter are insensitive to angle of attack up to 40°. 

Test temperature = 343°C, slurry jet velocity = 100 m/s, angle of attack of slurry stream = 50°. 

Each person should find the remaining parameters and physical property data for this material required to solve the three models [Eqs. (8.14), (8.19), and (8.20)] for the erosive wear of a coal slurry that is, each person will have three calculations to do and three erosion rates as a result. Assume that the test temperamre is 343°C, the slurry velocity is 100 m/s, and the angle of attack is 50°. 

Clide bombing. The action of bombing a target from a plane descending at a normal or nearly normal angle of attack with little or no thrust (Ref 3, pl36-L)... 

Fig. 5. Partial burble on airfoil al high angle of attack [A) siagnalion point 113) line of separuiion...

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