scispace - formally typeset
Search or ask a question
Author

T N.V. Satyanarayana

Bio: T N.V. Satyanarayana is an academic researcher from Indian Space Research Organisation. The author has contributed to research in topics: Rocket & Supersonic speed. The author has an hindex of 2, co-authored 2 publications receiving 62 citations.

Papers
More filters
Journal ArticleDOI
TL;DR: In this article, a short cylindrical supersonic exhaust diffuser (SED) is needed for use in vertical firing rocket test stands, and design methods are developed and presented in this paper for short SEDs.
Abstract: Short cylindrical supersonic exhaust diffuser (SED) is needed for use in vertical firing rocket test stands. Design methods are developed and presented in this paper for short SEDs. Incorporation of shock generators further helps in reducing its starting pressure.

33 citations

Journal ArticleDOI
TL;DR: In this article, the authors deal with the high-altitude simulation and testing of upper stage rocket motors with large nozzle area ratios, using second-throat exhaust diffusers (STED).
Abstract: This paper deals with the high-altitude simulation and testing of upper stage rocket motors with large-nozzle area ratios, using second-throat exhaust diffusers (STED). To evaluate the performance ...

32 citations


Cited by
More filters
Journal ArticleDOI
TL;DR: In this paper, an experimental study has been carried out on the mixing characteristics of a two-dimensional supersonic ejector with a two dimensional primary flow (air) of Mach number 2.48 and the secondary flow (subsonic) which is induced from the ambient.
Abstract: Key features that drive the operation of a supersonic ejector are the complex gasdynamic interactions of the primary and secondary flows within a variable area duct and the phenomenon of compressible turbulent mixing between them, which have to be understood at a fundamental level. An experimental study has been carried out on the mixing characteristics of a two dimensional supersonic ejector with a supersonic primary flow (air) of Mach number 2.48 and the secondary flow (subsonic) which is induced from the ambient. The non-mixed length, which is the length within the ejector for which the primary and secondary flow remain visually distinct is used to characterize the mixing in the ejector. The operating pressures, flow rates and wall static pressures along the ejector have been measured. Two flow visualization tools have been implemented—time resolved schlieren and laser scattering flow visualization. An important contribution has been the development of in-house image processing algorithms on the MATLAB platform to detect the non-mixed length from the schlieren and laser scattering images. The ratio of mass flow rates of the secondary flow to primary flow (entrainment ratio) has been varied in a range of 0.15–0.69 for two locations of the primary nozzle in the ejector duct. Representative cases have been computed using commercial CFD tool (Fluent) to supplement the experiments. Significant outcomes of the study are—the non-mixed length quantified from the flow visualization images is observed to lie within 4.5 to 5.2 times the height of the mixing duct which is confirmed by the wall static pressure profiles. The flow through the supersonic ejector in the mixed regime is explained using corroborative evidences from different diagnostic tools. A reduction of the non-mixed length by 46.7% is observed at operating conditions when the nozzle is sufficiently overexpanded. The disturbance caused to the mixing layer due to unsteady shock-boundary layer interactions within the nozzle at such conditions enhances mixing. The analysis of time resolved schlieren images have provided interesting observations on repetitive back and forth motion of the shock cells in the primary flow with a co-flowing secondary flow in the confines of the supersonic ejector. The oscillations have significant amplitudes (order of the nozzle height) at the centerline. The details of these experiments followed by the analysis of data and the inferences drawn from the results are discussed in this article.

58 citations

Journal ArticleDOI
TL;DR: In this article, the starting transient and plume blowback at diffuser breakdown of a straight cylindrical supersonic exhaust diffuser with no externally supplied secondary flow are numerically investigated.

36 citations

Journal ArticleDOI
TL;DR: In this paper, the design and operational parameters of rocket exhaust diffusers equipped to simulate high-altitude rocket performance on the ground were investigated and characterized using a comprehensive approach (theoretical, numerical, and experimental).
Abstract: The design and operational parameters of rocket exhaust diffusers equipped to simulate high-altitude rocket performance on the ground were investigated and characterized using a comprehensive approach (theoretical, numerical, and experimental). The physical model of concern includes a rocket motor, a vacuum chamber, and a diffuser, which have axisymmetric configurations. Further, the operational characteristics of a rocket exhaust diffuserwereanalyzed froma flowdevelopmentpointof view.Emphasiswasplacedondetailed flowstructure inthe diffuser, to observe the pressure oscillation in both the vacuum chamber and diffuser, which determines the minimum rocket-motor pressure required to start the diffuser. Numerical simulations were compared with experimental data on startup and in operational conditions to understand the effects of major design parameters, including the area ratio of diffuser to rocket-motor nozzle throat, the rocket-motor pressure, and the vacuumchamber size. Nomenclature Ad = inner cross-sectional area of diffuser Ade = exit cross-sectional area of diffuser Ae = exit cross-sectional area of rocket nozzle At = throat cross-sectional area of rocket nozzle

27 citations

Journal ArticleDOI
TL;DR: In this paper, an experimental investigation was conducted to study the Reynolds number influence on dual-bell transition behavior for tests inside a high-altitude simulation chamber, where the authors found that the width of the inflection region decreases with an increase in the nozzle Reynolds number.
Abstract: An experimental investigation was conducted to study the Reynolds number influence on dual-bell transition behavior for tests inside a high-altitude simulation chamber. For the range of nozzle supply pressures tested, the nozzle Reynolds number is seen to gradually decrease from a relatively high value (of the order of 107 for tests in sea-level atmospheric conditions) toward the transitional range (lower side of 106 for tests inside the high-altitude chamber). This influences the width of the inflection region, which is seen to decrease with an increase in nozzle Reynolds number. Because of the smaller negative pressure gradient experienced during sneak transition with a decrease in nozzle Reynolds number, the separation point is seen to move into the region of wall inflection much earlier and tends to stay in the region of wall inflection for a relatively longer time. Although the time duration of final transition remains more or less constant for different nozzle supply pressure values, the time durati...

24 citations

Journal ArticleDOI
TL;DR: In this paper, the effects of essential performance parameters on the starting transient of a straight cylindrical supersonic exhaust diffuser (SED) are numerically investigated in terms of SED length and pre-evacuation configuration.

24 citations