Engineering topics

Santoro, R. J.

Publications and source records attributed to Santoro, R. J..

27 records · Page 2

NASA NTRS1993

Flowfield characteristics in a liquid propellant rocket

Measurements of LOX drop size and velocity in a uni-element liquid propellant rocket chamber are presented. The use of the Phase Doppler Particle Analyzer in obtaining temporally averaged probability density functions of drop size in a harsh rocket environment has been demonstrated. Complementary measurements of drop size/velocity for simulants under cold flow conditions are also presented. The drop size/velocity measurements made for combusting and cold flow conditions are compared, and the results indicate that there are significant differences in the two flowfields.

Pal, S.↗

NASA NTRS1993

OH-radical imaging and velocity field measurements in a gaseous hydrogen/oxygen rocket

Detailed measurements of the OH-radical and velocity fields for a shear coaxial unielement rocket chamber burning gaseous hydrogen and gaseous oxygen propellants are reported. The velocity measurements indicate that a highly unsteady flowfield results from the turbulent combustion of the coaxial jets. The core of the oxygen stream is observed to remain intact well downstream of the injector face while the maximum turbulent intensities in the shear layer region between the hydrogen and oxygen flows were measured to be about 25 percent. Both 1D and 2D laser-induced fluorescence studies of the OH-radical are reported and provide information on the evolving flame structure under rocketlike conditions. Both single and multiple laser pulse images indicate that the structure of the unsteady flowfield is directly reflected in the combustion zone flame structure. Preliminary results regarding analysis approaches and interpretation of the data are also presented.

Moser, M. D.↗

NASA NTRS1993

Atomization characteristics of impinging liquid jets

A systematic study is presented of the atomization of impinging liquid jets investigating the effects of jet conditions (laminar versus turbulent), orifice diameter, impingement angle and jet velocity. Results are compared to current theories in terms of sheet breakup length, sheet shape and drop size. Experiments contrasting laminar and turbulent jet conditions clearly show that the jet conditions have a dramatic effect on the atomization process.

Ryan, H. M.↗

NASA NTRS1992

Experimental studies of characteristic combustion-driven flows for CFD validation

A series of rocket-related studies intended to develop a suitable data base for validation of Computational Fluid Dynamics (CFD) models of characteristic combustion-driven flows was undertaken at the Propulsion Engineering Research Center at Penn State. Included are studies of coaxial and impinging jet injectors as well as chamber wall heat transfer effects. The objective of these studies is to provide fundamental understanding and benchmark quality data for phenomena important to rocket combustion under well-characterized conditions. Diagnostic techniques utilized in these studies emphasize determinations of velocity, temperature, spray and droplet characteristics, and combustion zone distribution. Since laser diagnostic approaches are favored, the development of an optically accessible rocket chamber has been a high priority in the initial phase of the project. During the design phase for this chamber, the advice and input of the CFD modeling community were actively sought through presentations and written surveys. Based on this procedure, a suitable uni-element rocket chamber was fabricated and is presently under preliminary testing. Results of these tests, as well as the survey findings leading to the chamber design, were presented.

Santoro, R. J.↗

NASA NTRS1992

Fundamental studies of impinging liquid jets

Atomization caused by impinging two liquid jets at an angle was studied experimentally and analytically. Measurements of drop size, sheet length and width at breakup, and apparent wave structures on the liquid sheet surface were made for different flow conditions and different geometries. The breakup of the attenuating liquid sheet into ligaments was modeled by linear stability theory. Breakup lengths were predicted from the fastest growing wave on the sheet surface, and drop diameters were calculated based on surface tension-controlled breakup of the ligaments.

Anderson, W. E.↗

NASA NTRS1992

Shear coaxial injector atomization phenomena for combusting and non-combusting conditions

Measurements of LOX drop size and velocity in a uni-element liquid propellant rocket chamber are presented. The use of the Phase Doppler Particle Analyzer in obtaining temporally-averaged probability density functions of drop size in a harsh rocket environment has been demonstrated. Complementary measurements of drop size/velocity for simulants under cold flow conditions are also presented. The drop size/velocity measurements made for combusting and cold flow conditions are compared, and the results indicate that there are significant differences in the two flowfields.

Pal, S.↗

NASA NTRS1991

Spray characterization using planar laser imaging

Results on the application of a planar polarization ratio technique to spray and soot particle measurements are presented and compared with the phase Doppler particle analyzer (PDPA) measurements. With the assumption of a logarithmic normal distribution, reasonable agreement between the two techniques were obtained, demonstrating the capability of the planar polarization ratio technique to differentiate regions containing soot particles from those containing droplets. A comparison of quantitative measurement capabilities of the two techniques showed that the planar polarization ratio technique can be applied to complicated combustion environments for at least semiquantitative investigation of sprays.

Pal, S.↗

NASA NTRS1991

Cryogenic combustion laboratory

The objective is to establish a major experimental laboratory for studying fundamental processes such as mixing and combustion under liquid rocket engine conditions. The capability of this laboratory will include operation using a variety of fuel and oxidizer systems including liquid oxygen and liquid hydrocarbons. In addition to providing the proper facilities for supplying and controlling these fuels and oxidizers, a specific effort is being made to provide a state-of-the-art diagnostic capability for combustion measurements. In particular, optical and laser-based techniques are being emphasized for measurements of species, velocities, and spray characteristics.

Santoro, R. J.↗

NASA NTRS1991

Spray combustion under oscillatory pressure conditions

The performance and stability of liquid rocket engines is often argued to be significantly impacted by atomization and droplet vaporization processes. In particular, combustion instability phenomena may result from the interactions between the oscillating pressure field present in the rocket combustor and the fuel and oxidizer injection process. Few studies have been conducted to examine the effects of oscillating pressure fields on spray formation and its evolution under rocket engine conditions. The pressure study is intended to address the need for such studies. In particular, two potentially important phenomena are addressed in the present effort. The first involves the enhancement of the atomization process for a liquid jet subjected to an oscillating pressure field of known frequency and amplitude. The objective of this part of the study is to examine the coupling between the pressure field and or the resulting periodically perturbed velocity field on the breakup of the liquid jet. In particular, transverse mode oscillations are of interest since such modes are considered of primary importance in combustion instability phenomena. The second aspect of the project involves the effects of an oscillating pressure on droplet coagulation and secondary atomization. The objective of this study is to examine the conditions under which phenomena following the atomization process are affected by perturbations to the pressure or velocity fields. Both coagulation and represent a coupling mechanism between the pressure field and the energy release process in rocket combustors. It is precisely this coupling which drives combustion instability phenomena. Consequently, the present effort is intended to provide the fundamental insights needed to evaluate these processes as important mechanisms in liquid rocket instability phenomena.

Jacobs, H. R.↗