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Heat transfer coefficient measurements on curved surfaces

100%

Kurowski M.

tom Vol. 42, no 2

155--170

This paper presents the results of experimental research on heat transfer distribution under the impinging jets at high jet velocity on curved surfaces. The air jets flow out from the common pipe and impinge on a surface which is cooled by them, in this way all together create a model of external cooling system of low pressure gas turbine casing. Preliminary measurement results from the flat plate case were compared with the results from the curved surface case. Surface modification presented in this paper relied on geometry change of flat surface to the form of a ‘bump’. The special system of pivoted mirrors was implemented during the measurements to capture the heat exchange on curved surfaces of the bump. The higher values of mean heat transfer coefficient were observed for all flow cases with a bump in relation to the reference flow case with a flat plate.

Test section design for measuring the drag coefficient of a suborbital rocket model at Ma 2.45

51%

Wasilczuk F. , Kurowski M. , Flaszyński P.

Transactions on Aerospace Research

2024

tom Nr 3 (276)

86--100

This study investigates the drag coefficient of three models of suborbital rockets with different nosecones. A test section allowing for force measurement of a 1:50 scale rocket model was designed with the aid of numerical simulations. The velocity obtained in the wind tunnel corresponds with a Mach number of 2.45. RANS simulations were used in verifying operating parameters, as well as testing the support configurations for connecting the model with the bottom wall of the tunnel section. Pressure distribution measurements on the top and bottom walls of the wind tunnel matched simulation results well. The shock structure in the test section was visualized using the schlieren technique, revealing that the measured angle of the main shock generated at the tip of the rocket matched the simulation data. Finally, the measured forces were compared with simulations for one of the nosecone configurations. Despite very good agreement for pressure distribution on the wind tunnel walls and shock structure, a significant mismatch in the forces measured was nevertheless observed: the simulated CD (0.57) being four times larger than that obtained in measurements (0.138). Further analysis of the test section is required to pinpoint the source of discrepancies and redesign the force measurement system to achieve improved force results.

Open low speed wind tunnel – design and testing

38%

Szwaba R. , Hinc K. , Ochrymiuk T. , Krzemianowski Z. , Doerffer P. , Kurowski M.

Archives of Thermodynamics

2021

tom Vol. 42, no 1

57--70

This paper presents the design method and the construction details of a subsonic low-speed wind tunnel, which has been designed to achieve the flow velocity of 35 m/s in the measurement section with expected uniform velocity field at its inlet. To achieve such objectives a very detailed design was performed using a theoretical 1D analysis and computational fluid dynamics simulations. This approach was applied to improve the flow quality along the wind tunnel sections. When the wind tunnel has been launched a direct comparison of the experimentally measured flow field in the test section and numerical simulation results was conducted. Such comparison of the simulation results with the experimental one is presented in this paper. The obtained results confirm that assumed wind tunnel design method was correct, i.e. the pressure drop in the wind tunnel has been predicted very well and drive system is effective and sufficient to accelerate the airflow to required values.