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The alternate oxidizer turbo-pump inducer development has been carried out to improve the suction performance of the LE-7A rocket engine. CFD was utilized for the design and development of the alternate inducer. For the first step, non-cavitating CFD was applied to verify the blade the design concept. Next, steady state cavitating CFD was carried out to predict suction performance. Finally, large-scale unsteady cavitating CFD was performed to evaluate the cavitation-induced instability. In the present paper, the application of CFD for the development of the alternate inducer will be presented.

The prediction of vibration generated from the turbopump is becoming increasingly important in rocket engine development. In some cases, the vibration of the turbopump originates from the interaction between the rotating impeller and the stationary parts such as diffuser vanes and casing tongues. The present paper describes the application of the numerical code developed by one of the authors (Kato) to predict the flow-induced vibration in the liquid hydrogen pump of the LE-7A rocket engine. The source fluctuations of the flow field are computed by a large-eddy simulation (LES) with the Dynamic Smagorinsky Model (DSM) and the results are fed to the structural vibration analysis, which will be presented elsewhere. Computations of the unsteady flow in the entire liquid hydrogen pump were carried out. Water tunnel experiments were also carried out to obtain validation data and were compared with the numerical results. The computed static pressure distribution and pressure fluctuation agree fairly well with the measured data, which demonstrates that the proposed method can serve as a practical tool for predicting unsteady flows in a rocket engine pump.

Axial compresso rs are often subject to poor inflow conditions which range from steady state , but spatially asymmetric velocity profiles due to imperfect intake geometry to time varying ingested vortices, turbulence or secondary inflow distortion s. The resulting periodic and/or random forces acting on the blades cause tonal and/or broadband interaction noise which sometimes dominates the noise radiation of the compressor . In th e present study, we appl y the large eddy simulation (LES) method to pre dict the unsteady forces on the blades of a single stage low pressure axial flow compressor without guide vanes. T urbulence is generated by a turbulence grid installed upstream of the impeller’s leading edge plane. The LES shows that the complex wake/vorte x flow downstream of the turbulence grid produces both , “random” (i.e. broadband) and periodic velocity fluctuations. The predicted blade response to the inflow turbulence (in terms of surface pressure fluctuations in the blade leading edge region) is in g ood agreement with our own surface pressure measurements. Assuming the impeller to be placed in an infinitely long duct a simple algebraic acoustic model proposed by Morfey is employed to predict the duct sound spectrum . By way of contrast, assuming a very short duct type inlet , the Ffowcs Williams and Hawkings analogy is employed to predict the spectral free field suction side sound pressure. Employing the LES data the acoustic calculation s yield a good first estimate of the absolute levels of the radiated sound. Also, the characteristic differences between clean inflow (i.e. without turbulence grid) and highly turbulent inflow are reasonably well predicted as compared to experiments. Discrepancies are attributed to insufficient boundary layer reso lution , t he omission of the tip clearance , and the limitations of the acoustical model s.

The objective of this investigation is to develop a method for detecting the aerodynamic sound source in a low-Mach number turbulent wake. In order to evaluate vorticity contribution for the dipole sound generation, a compact Green's function is utilized for identification of the aerodynamic sound source. The compact Green's function (1) (2) denotes the acoustic efficiency of the surface dipole caused by the interaction between the vorticity fluctuation and solid surfaces. The surface dipole sources and vorticity fluctuation are measured (3)(4) in the wake of a circular cylinder with Reynolds number of 4.0×10 4 . The compact Green's function model can be estimate instantaneous sound source distribution, however, this method requires the spatial derivative of vorticity fluctuations. Therefore, experimental evaluation is difficult. To evaluate the compact Green's function method, we introduce coherent output power (COP) in terms of surface dipole and vorticity fluctuation (4) . This method can be estimated vorticity contribution to the dipole sound generation with measurement of the coherence output power in terms of the vorticity fluctuation and the surface (dipole) pressure. This method is based on the conventional Lighthill-Curle's theory (5) , which shows the aerodynamic sound is calculated with the surface pressure fluctuation. The COP method makes use of the coherent output power instead of the surface pressure fluctuation, it is found that the intensity of COP corresponds to the distribution of the dipole sound source caused by unsteady vorticity fluctuation. The estimated sound source distribution with the compact Green's function model is good agreement with that of the COP method.