Engineering topics

Petersohn, E

Publications and source records attributed to Petersohn, E.

3 records

NASA NTRS1932

Application of the theory of free jets

Based upon Kirchoff's theory of free jets the flow through different screen arrangements of flat plates, as chiefly encountered with turbines in the cavitation zone is defined. It is shown by experiments that these theoretical results are very well representative in most cases of the conditions of discharge from water in air and consequently by cavitation. In addition, the experiments reveal a picture of the discrepancies between the actual flow and the theory of discharge of air in air (of water in water without cavitation). These discrepancies are explained qualitatively by the mingling processes between the jets and the dead air zones.

Betz, A↗

NASA NTRS1931

Downwash measurements behind wings with detached float

This investigation, which was made in the small wind tunnel having a diameter of 1.2 m (3.94 feet), embraced three wing models, behind which, at various angles of attack between 0 and 60 degrees, the static pressure and the total pressure along vertical lines (perpendicular to the direction of the undisturbed wind and to the wing span) were measured. The location of these vertical lines are indicated in Figure 1. Moreover, the wing polars were determined by the customary three-component measurements. For testing the pressure field, a Pitot tube and a static probe, both of 2 mm (0.08 in.) in diameter, were mounted 40 mm (1.57 in.) apart on the end of a shaft 1 m (39.37 in.) long.

Petersohn, E↗

NASA NTRS1929

Contribution to the aileron theory

In an attempt to treat theoretically the effect of ailerons, difficulty arises because an aileron may begin at any point of the wing. Hence the question arises as to how the transition of the lift distribution proceeds at such a point, since the effect of the aileron (i.e., the moment generated about the longitudinal axis) depends largely on this distribution. In order to answer this question regarding the lift distribution during irregular variations in the angle of attack at first independently of other influences, especially those of the wing tips, we have taken as the basis of the following theoretical discussion a wing of infinite span and constant chord which exhibits at one point an irregular variation in the angle of attack. As regards the mathematical treatment, we will first consider a wing with periodically recurring angle of attack.

LIFT DISTRIBUTION - WINGS↗