SUPERSONIC FLOW FIELD IN WIND TUNNELS: PARTICULARITIES AND OPTIMIZATION OF MEASUREMENT OF RELEVANT PARAMETERS

Dijana Damljanović

Đorđe Vuković

Abstract:

The subject of the scientific technical information are specific problems and interaction of different phenomena related to fluid flow in test sections of supersonic wind tunnels that is presented using the T-38 trisonic wind tunnel of the Military Technical Institute in Belgrade as an example.

An analysis of posibilities to improve quality of wind tunnel measurements is primarily presented in the scientific technical information. Existing methodologies and all the factors which facilitate or make difficult the use of some methods of the relevant flow field parameters measurement had been studied and the optimal methodology with the increased accuracy level was defined and, based on this, the primary measuring system was reconfigurated and improved in accordance with all specifications of the T-38 wind tunnel in the supersonic flow conditions.

Scientific technical information is based on a theoretical-numerical analisys of possibilities to improve accuracy of the measurement of supersonic flow field parameters and the analysis of experimental results of a relativly large number of wind tunnel tests in the framework of the new primary measuring system of the T-38 wind tunnel. Performed experiments comprised measurements of primary flow field parameters, Mach number, stagnation pressure and flow angularities, in the central area of T-38 test section in the supersonic part of the wind tunnel operating envelope as well as testing of a supersonic-hypersonic model of the standard geometry. The analysis also included correlations with the results from commissioning tests in the T-38 wind tunnel and with relevant results from leading world wind tunnel laboratories.

Verification of the theoretical-methodical improvements of the measurement accuracy of supersonic flow field parameters in wind tunnels of the T-38 type was performed by testing of a supersonic-hypersonic model of a standard geometry and obtained results were compared with those from the worlds’ referential supersonic wind tunnels. Aerodynamic characteristics of the standard model obtained in the wind tunnel tests confirmed improvements of the wind tunnel measurement quality.

Key words: wind tunnel, supersonic flow, flow field, aerodynamic testing, measurement system, parameters measurement, Mach number, aerodynmic model, calibration, verification.