The paper presents a study of the flow that occurs in a finite, parallel plate channel. The experimental work consists of velocity profile measurements upstream of and inside the channel of a belt-type apparatus. Theoretical prediction of velocity profile development is made via numerical methods in both laminar and turbulent situations. In the laminar flow case analytical solution of a linearized form of the momentum equation was also possible. Good agreement is shown between prediction and experimental results for all Reynolds numbers tested; in turbulent flow this occurs particularly when employing Reichardt’s eddy viscosity model. For laminar flow the entrance length is estimated to be 0.008–0.01 times the Reynolds number, while in turbulent flow no essential difference was found between an entrance and the corresponding asymptotic profile. Upstream from the entrance the similar laminar profiles of Sakiadis were observed experimentally.

The present work supplements a previous analysis by Azoury of the basic wave processes in a d.p.e. (dynamic pressure exchanger) cell. A hybrid computerized method of integrating the differential equations of unsteady one-dimensional ideal gas flow is used to analyse the component scavenge processes of the d.p.e. in a looped arrangement. These processes are employed to investigate the effect of the relative nature of the interacting gases on d.p.e. performance. A criterion of high performance is proposed in terms of the overall strength of the interface between the gases and their relative specific heat ratios. The criterion gives good agreement with theory when tested with experimental results obtained on two d.p.e. test units.

As the mission requirements of the aero engine improve, the blade aerodynamic loading is higher, especially for lightweight designed blade. The possibility of the blade self-excited vibration increases, so flutter becomes one of the problems for fan and compressor design. However, there is no flutter related parameters in engineering as a reference for compressor flutter-free design until now. That is why the sensitive flutter parameters were studied which could suppress the flutter. Nomenclature W aerodynamic work A blade surface area T, t time V positive direction of blade oscillation n positive direction of pressure P pressure of blade surface

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