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Slutsky, S.

Publications and source records attributed to Slutsky, S..

10 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Computation of unsteady transonic flows through rotating and stationary cascades. 3: Acoustic far-field analysis

A small perturbation type analysis has been developed for the acoustic far field in an infinite duct extending upstream and downstream of an axial turbomachinery stage. The analysis is designed to interface with a numerical solution of the near field of the blade rows and, thereby, to provide the necessary closure condition to complete the statement of infinite duct boundary conditions for the subject problem. The present analysis differs from conventional inlet duct analyses in that a simple harmonic time dependence was not assumed, since a transient signal is generated by the numerical near-field solution and periodicity is attained only asymptotically. A description of the computer code developed to carry out the necessary convolutions numerically is included, as well as the results of a sample application using an impulsively initiated harmonic signal.

Slutsky, S.↗
NASA NTRS1975

Ambient and induced pressure fluctuations in supersonic jet flows

An experimental investigation of the ambient static pressure fluctuations and induced acoustic fields in supersonic jet flows has been undertaken to identify possible noise sources and the mechanisms involved in the propagation of disturbances within the flows. The axisymmetric cold air jet under investigation exhausted from a 7-in. exit diameter C-D nozzle run in two conditions: one yielding a fully expanded flow and the other an overexpanded flow. The survey of static pressure fluctuations consisted of measurements of the overall levels and spectra of the fluctuations along the centerline of the two flows and the variation in level across various transverse sections. The second aspect of the study involved the development of a procedure for tracing the propagation of externally induced periodic pressure disturbances inside the jet.

Barra, V.↗
NASA NTRS1975

Time-dependent transonic flow solutions for axial turbomachinery

Three-dimensional unsteady transonic flow through an axial turbomachine stage is described in terms of a pair of two-dimensional formulations pertaining to orthogonal surfaces, namely, a blade-to-blade surface and a hub-to-casing surface. The resulting systems of nonlinear, inviscid, compressible equations of motion are solved by an explicit finite-difference technique. The blade-to-blade program includes the periodic interaction between rotor and stator blade rows. Treatment of the boundary conditions and of the blade slipstream motion by a characteristic type procedure is discussed in detail. Harmonic analysis of the acoustic far field produced by the blade row interaction, including an arbitrary initial transient, is outlined. Results from the blade-to-blade program are compared with experimental measurements of the rotating pressure field at the tip of a high-speed fan. The hub-to-casing program determines circumferentially averaged flow properties on a meridional plane. Blade row interactions are neglected in this formulation, but the force distributions over the entire blade surface for both the rotor and stator are obtained. Results from the hub-to-casing program are compared with a relaxation method solution for a subsonic rotor. Results are also presented for a quiet fan stage which includes transonic flow in both the rotor and stator and a normal shock in the stator.

Erdos, J.↗