Sher Khan
(P A College of Engg, India)

The analysis of Supersonic/Hypersonic flow over cones, wedges, ogives over a considerable incidence range is of current interest with the advent of space shuttle and high performance military aircrafts. The knowledge of aerodynamic load and stability for such types of configuration is of increasing demand. In particular there is a need for simple but reasonably accurate methods for parametric calculations facilitating the design process. When descending at Supersonic / Hypersonic speeds, the vehicles encounter shock waves, which are usually strong and can be either detached or attached. A strip theory is used in which strips at different span-wise locations are independent. This combines with the similitude to give a piston theory. The present theory is valid only for attached shock case. Effects of wave reflection and viscosity have not been taken into account. Some of the results have been compared with those of Hui (1982), Ghosh (1984), and Liu & Hui (1977). Results have been obtained for hypersonic flow of perfect gas over a wide range of Mach numbers, incidences and sweep angles. A good agreement is obtained with Hui. in some special cases.

Makiko Yonamine
(University of the Ryukyus, Japan)

Supersonic jet noise problems have long been a very important issue in many diverse engineering applications such as supersonic aircraft jet propulsion thrust vectoring, fuel injector for supersonic combustion, soot blower device, thermal spray device, etc. A great deal of experimental and numerical researches has been carried out to spray the transonic tone, Zaman et al. investigated the characteristics of the transonic tone in carious nozzle condition of the frequency from a collection of data for single round nozzles. Moreover, they showed that transonic tone take place similarly to the no-flow longitudinal acoustic resonance of a conical section having one end closed and the other end open. However, it remains unclear under what process the transonic tone can occur in actual flow complicated by shock oscillation and shock wave/boundary layer interaction. The objective of this study is to investigate the characteristics and generation mechanism of transonic tone in two-dimensional supersonic nozzle. In this paper, to clarify the relationship between oscillation frequency of first-shock wave and frequency of transonic tones, the general behaviour of the wall static pressure, the sound pressure spectrum and the visualization of shock waves in the supersonic nozzle by using a schlieren method are shown.

Uliiana Tuchina
('Yuzhnoye', Ukraine)

The scientific & technical principles of the new method of low-frequency vibrations generating based on the aerodynamic type sources are developed. The interaction between steady speed supersonic flow and solid that cause cyclical shock waves was assumed as the base of the method. Acoustic vibrations are generated in the air as the harmonic components of the process. The analytic relation that allows to calculate the sound pressure value in the long-range acoustic field of transmitter was deduced in context of linear acoustic. Present article shows the Fourier transformation results for case of cyclical shock waves effect with frequency equal 20 Hz to the continuum stationary air. Cyclical shock waves are appeared due to operation of the converter of constant supersonic flows into the acoustic vibrations. The methodology that allows analyzing the spectrum components is developed. Concluded that the low-frequency components are the most energy intensity components in spectrum. Diagrams of directivity characteristics of the first five components are presented.

Trevor Moulden
(University of Tennessee Space Institute, USA)

The objective of a turbulence model is to replace the information lost when the Reynolds decomposition, v goes to V + u, is carried out on the Navier Stokes Equations. Several distinct problems arise when discussing such turbulence models: 1). The mean motion equations and a turbulence model may result in a set of differential equations that do not possess a solution ( Moulden [2008, 2010]) 2). There is no uniqueness in the specification of the Reynolds decomposition ( Moulden [2009]) since a gauge field can always be introduced into the field equations. The Reynolds tensor does not recover the lost information induced by the Reynolds decomposition. The paper will evaluate turbulence models in global norm for some periodic domain D. Some measure of the approximation made by the introduction of a turbulence model can be obtained from the difference W between the global norms of the mean and instantaneous velocities. W depends only on the norms of the Reynolds tensor and the body force. Now the evolution of the parameter W depends upon both the model for the Reynolds tensor and upon the body force norm. The role of gauge fields will be of particular interest in the discussion.

Shinichi Yoda
(ISAS, Japan)

The transition behavior from transition behavior for stationary to oscillatory flow in Marangoni convection have been contradiction so far. Many works regarding to this have been done so far, but there is no exact answer come arise by using several kinds of opportunity such as sounding rocket, space shuttle as well as ISS. A modeling has proposed to explain the behavior. Although the liquid bridge keep similarity, the critical Marangoni number for the transition have been changed with each other. We have been doing systematic experiments by using our JEM with changing parameter such as aspect ratio. We will present clear transition mechanism by using exact experimental results obtain from micogravity and our modeling.

Tsung-Han Lin
(National Defense University, Taiwan)

This work is related to a numerical investigation of the Rayleigh-Benard (RB) problem of convective rarefied gas flows in horizontal rectangular 3D-enclosures by using Direct Simulation Monte Carlo (DSMC) method. Major concerns are convective flow instability, mode-transition, and influences of side-wall boundary conditions. In DSMC simulations of Rayleigh-Benard convection, specular reflection conditions are usually specified for lateral side boundaries. However, a real enclosure is bounded by solid walls. The present work is thus also aimed to apply an improved gas-solid collision rule for modeling adiabatic wall. This gas-solid interaction model keeps the particle velocity magnitude invariant and the velocity direction of the reflected particle is set based on isotropic scattering uniform distribution in the half space. This boundary treatment is physically more reasonable for description of reflected molecules at adiabatic solid surface. Various combinations of specular reflection (SP) and isotropic scattering (IS) conditions prescribed for the four side walls are studied. Different flow pattern formations such as contra-rotating cells or organized rolls have been observed in each case. From effective DSMC calculation and numerical visualization, insight into the effects of adiabatic side wall boundary conditions on the convective flow characteristics of this classical problem can be obtained.