Modeling of High-Velocity Flows in ITAM Impulse Facilities
Abstract
It is well known that wind tunnels widely used at hypersonic velocities, are impulse and high-enthalpy facilities. These tunnels are based on different operation principles. Because of the short test time in these facilities, it is necessary to estimate the times characterizing the duration of certain events (tau sub ev) in the flow around various models. In the flow around an oscillating body, for example, (tau sub ev) equals the oscillation period, and (tau sub ev) = infinity in the flow around a body moving with a constant velocity. If the model is rapidly inserted into the test section of the wind tunnel, it is important to determine the time of flow stabilization tau sub stab. Each wind tunnel (WT) also has its own characteristic time tau WT (time during which the stagnation parameters change by a certain factor). For instance, if the behavior of these parameters in the settling chamber is close to exponential, tau WT may be assumed to be equal to the time needed for the parameters to change by a factor of e. Interaction between the facility and the model is characterized by one more characteristic time. The model length being assumed to be Lmod, the fore and rear parts of the model experience the action of gas portions that leave the settling chamber at different times (change in tau = t sub in ~ Lmod/upsilon sub infinity, where upsilon sub infinity is the freestream velocity in the test section); correspondingly, these gas portions have different stagnation conditions. Hence, the greater the value of tau sub in, the more non uniform is the flow around the model. Obviously, the relative non-uniformity is determined by the ratio t sub in/t sub WT. The lower this ratio, the more grounds are for neglecting it. The ratio tstab/tWT is subjected to similar requirements. If this ratio is small, this means that the flow pattern has enough time to follow the changing free-stream parameters.
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 2010
- Accession Number
- ADA592568
Entities
People
- A. M. Kharitonov
Organizations
- Russian Academy of Sciences