The experiments of primary and secondary instabilities with controlled excitation are carried out on a swept flat plate to study the process leading to the final breakdown of laminar flow. Two types of high frequency ...The experiments of primary and secondary instabilities with controlled excitation are carried out on a swept flat plate to study the process leading to the final breakdown of laminar flow. Two types of high frequency secondary instabilities are identified. The most amplified mode is centered about the inflection point of the crosswise profile of the boundary layer and is interpreted as inflectional instability, the other occurs in the one third of the boundary layer from the wall. The high frequency disturbances are highly amplified but they also saturate similarly to the primary and nonlinearly generated disturbances. Their main effect in the final breakdown seems interact with the disturbances is developed and thus widens the frequency spectrum to turbulent state.展开更多
文摘The experiments of primary and secondary instabilities with controlled excitation are carried out on a swept flat plate to study the process leading to the final breakdown of laminar flow. Two types of high frequency secondary instabilities are identified. The most amplified mode is centered about the inflection point of the crosswise profile of the boundary layer and is interpreted as inflectional instability, the other occurs in the one third of the boundary layer from the wall. The high frequency disturbances are highly amplified but they also saturate similarly to the primary and nonlinearly generated disturbances. Their main effect in the final breakdown seems interact with the disturbances is developed and thus widens the frequency spectrum to turbulent state.
