ISSN Online: 2377-424X
ISBN Print: 0-85295-345-3
International Heat Transfer Conference 10
EFFECTS OF TRANSVERSE OSCIILATORY WAVES ON TURBULENT BOUNDARY LAYERS
要約
Many flow fields are characterized by velocities
with time-dependent oscillating components. Rocket
motors, for example, exhibit instabilities which can lead
to longitudinal, circumferential, and radial oscillations
in pressure and velocity. Such oscillations in the flow
field can and have led to the loss of the motor due to
excessive wall heat transfer. Since it has been shown
that early transition to turbulence for such flows is
generally not sufficient to cause motor failure, a
probable cause is the increase in heat transfer due to a
coupling between the turbulent and periodic
oscillations.
The instabilities found in solid rocket motors are primarily longitudinal in nature and usually occur at low frequencies. This tends to decrease the severity of the turbulent oscillatory coupling. Liquid rocket motors, however, are subject primarily to transverse oscillatory modes (i.e. circumferential and radial) which occur at higher frequencies, and make the problem a transient three-dimensional one.
In the present paper, the effects of transverse oscillatory waves are examined. A turbulent boundary layer with a uniform axial flow is subjected to a transverse velocity oscillation from 0 to 1000 rad/sec and amplitude of 0 to 75% of the axial free stream velocity. These amplitudes are consistent with those associated with liquid rocket motor potential instabilities; although, the frequencies in rocket motors are typically often higher.
The instabilities found in solid rocket motors are primarily longitudinal in nature and usually occur at low frequencies. This tends to decrease the severity of the turbulent oscillatory coupling. Liquid rocket motors, however, are subject primarily to transverse oscillatory modes (i.e. circumferential and radial) which occur at higher frequencies, and make the problem a transient three-dimensional one.
In the present paper, the effects of transverse oscillatory waves are examined. A turbulent boundary layer with a uniform axial flow is subjected to a transverse velocity oscillation from 0 to 1000 rad/sec and amplitude of 0 to 75% of the axial free stream velocity. These amplitudes are consistent with those associated with liquid rocket motor potential instabilities; although, the frequencies in rocket motors are typically often higher.