S. V. Guvernyuk

Experimental investigation of single-mode panel flutter in supersonic gas flow

Panel flutter theory distinguishes between two types of the loss of stability, namely, the flutter of the coupled type and the single-mode flutter. The flutter of the coupled type is well studied, both theoretically and experimentally. The single-mode flutter has been theoretically studied only quite recently. This study is devoted to the experimental investigation of the single-mode panel flutter. The fact of its generation under actual conditions is established and the stability range is determined.

Isobaric Separation Structures in Supersonic Flows with a Localized Inhomogeneity

It is known that the presence of a small inhomogeneity in a uniform supersonic flow can lead to the global restructuring of the flow around bodies. An aerodynamic wake behind a solid particle [1] or a thermal wake from a source of external power supply [2] are typical examples of the formation of a localized inhomogeneity in the supersonic flow. 1 One of the brilliant manifestations of the capability of the small inhomogeneity to induce the global restructuring of the flow is the formation of a large separation region formed in the supersonic flow in front of a blunt body; this region displaces the bow shock wave far ahead with a simultaneous sharp decrease in the wave drag of the body [3]. Such a phenomenon is observed in many physical [4, 5] and computational [6‐9] experiments. The idea to affect the structure of gas flows by means of artificial inhomogeneity sources (e.g., solid particles, pellets, thrown to the supersonic counter flow [1, 10, 11] or “spots” of intense heat supply that are created in the flow in front of the body by means of various electric or laser optic discharges [4], etc.) has been considered by many researchers as a new method for controlling the aerodynamic characteristics of promising aircraft [13]. Configurations of flows with global separation induced by the small inhomogeneity are similar to an example of the nonunique solution of the problem on the supersonic flow around bodies that is known in the gas-dynamics course [14]: in a uniform supersonic flow in front of a round cylindrical body, a conical region of immobile gas can exist, which is separated from the external flow by the tangential discontinuity surface (see Fig. 1). Since various pressure values can exist in 1 There is no fundamental difference between these two variants of the inhomogeneity, because the dynamic component of the inhomogeneity is determining in both cases [10, 12]. this dead zone, there are an infinite number of conical configurations of the dead zone in front of the body. The selection of one of them is impossible without additional information on the causes of the separation of the flow from the body [14]. In this work, the problem of the selection of a single solution is analyzed for the case where the cause of the appearance of a large separation region is a small inhomogeneity in the incident supersonic flow. It is shown that an inviscid steady flow with an isobaric dead zone exists under certain conditions. This flow in the local inhomogeneity scale is a flow with a separated compression shock and, upon transition to the external global scale, is continuously transformed to a self-similar supersonic flow with a thin entropy layer at the boundary of the dead zone, where the pressure is equal to the total pressure p 01 behind the normal shock in the inhomogeneity core. The parameter p 01 selects a single configuration with the conical dead zone in front of the body. The corresponding flow is a

Numerical and physical modeling of the circulation flow in a vortex cell in the wall of a rectilinear channel

The results of physical and numerical modeling of the three-dimensional vortex flow in a circular cell forming a recess in the wall of a rectangular constant-area channel are presented.

NUMERICAL AND PHYSICAL MODELING OF TURBULENT FLOW IN A DIVERGENT CHANNEL WITH A VORTEX CELL

Turbulent flow in a channel with a vortex cell is analyzed numerically and experimentally. The influence of the rotation of a central body in a vortex cell, the viscosity, and the pressure gradient on the local and integral characteristics of the flow is evaluated.

Experimental observation of single-mode panel flutter in a supersonic gas flow

Abstract. Single mode flutter is a type of panel flutter, which cannot be analyzed theoretically using conventional piston theory, and for this reason it is studied very little. No previous experiments, where this type of panel flutter was detected, were conducted. In this paper a plate, designed such that it cannot experience ”classical” coupled-type flutter, but can experience single mode flutter, is tested. Analysis of the tested data clearly indicates the occurrence of single mode panel flutter.

Experimental Investigation of Three-Dimensional Supersonic Flow past an Axisymmetric Body with an Annular Cavity

The results of an experimental investigation of supersonic Mach 2.5 flow past an axisymmetric cylindrical model body with a rectangular annular cut-out on its lateral surface are presented. The evolution of the structure of the flow over the cavity with continuous variation in the angle of attack is studied on the basis of the data of flow visualization and balance measurements on the range of the relative cavity lengths L/h from 8 to 16. Hysteresis phenomena are revealed and analyzed.

EXPERIMENTAL STUDY OF SINGLE MODE PANEL FLUTTER

Single mode flutter is a type of panel flutter, which cannot be analyzed theoretically using conventional piston theory, and for this reason it is studied very little. In this paper a plate, designed such that it cannot experience “classical” coupled-type flutter, but can experience single mode flutter, is tested. Analysis of the tested data clearly indicates the occurrence of single mode panel flutter.Copyright