A Study on the Flow Physics of Altitude Adaptive Nozzles

International Journal of Engineering Materials and Manufacture, 2019

Space exploration and space tourism have now become a raging competition among developed nations. For this reason, different types of advanced rocket nozzles with prospective privileges are introduced. Altitude adaptive dual-bell nozzle will soon replace the conventional nozzles for the first stage rocket launcher. Indeed, this nozzle has auto adaption capability based on altitude. The major feature of a dual-bell nozzle is the two bell-shaped contours separated by an inflection point. This nozzle has left rooms for researchers to test different flight conditions and transition characteristics. In this paper, a dual-bell nozzle contour has been developed in MATLAB and analyzed for different thermodynamic parameters. ANSYS Fluent is used in analyzing flow through the nozzle. The shadowgraph imaging technique is used for measuring density gradient and compared it with fluent results. The simulations were performed using the k-epsilon turbulence model.

Concept of Altitude adaptive rocket nozzles recently received greater importance and interest in the space explorations and other such applications in space and rocket technology. The operations reliability of rocket launcher and the earth to orbit rocket launch are the crucial for the space transportation in the future. The performance of the engine components such as the power plant and the thrust delivery of the engine such as nozzles are in renovation for the greater performance and applicability for complex space applications. In the recent progress of the combustion expansion system the rocket nozzles are greatly revised from both application and design perspectives. One of such development is the dual bell nozzle. The publications indicate that the research on the concept of dual bell nozzle is tardy and there is no much progress from the inception of the idea. The specific application purpose designs are tested experimentally and implemented but the large scale development can only be possible if the generalized design parameters can be suggested. In the present paper one of such nozzle is selected and studied using computational fluid dynamics (CFD) and the results are synthesized for bench marking the general approach to study the Dual Bell nozzles. The result shows the variation in the Mach number, pressure, temperature distribution and turbulence intensity.

PROCEEDINGS OF THE INTERNATIONAL ENGINEERING RESEARCH CONFERENCE - 12TH EURECA 2019, 2019

Double Divergent Nozzle is a type of altitude compensating nozzle having less weight and minimum modifications when compared to other altitude compensating nozzle concepts. Planar double divergent nozzle is similar to a dual bell nozzle but, it is having a rectangular cross section. The present study involves numerical analysis of a planar double divergent nozzle and its comparison with a single divergent nozzle using ANSYS Fluent Software. The flow is simulated over various Nozzle Pressure Ratios (NPRs) and corresponding wall static pressure and specific impulse are studied. A sneak transition can be observed when the flow changes from low altitude mode to high altitude mode. The transition occurs early for double divergent nozzle having low NPR and vice versa. The wall static pressure variation shows a strong dependence of inflection angle on pressure variation, separation location and recirculation regions inside the nozzle.

International Conference on Mechanical, Industrial and Materials Engineering-2017, 2017

Altitude adaptive nozzles have recently got more importance in the field of space science and rocket technology. For future space exploration and space tourism, the combustion system is in the refurbishment for better and robust performance. As a part of this progression, dual bell nozzle is introduced which has dual operating modes (at low and high altitude) without any mechanical activation. The main feature of dual-bell nozzle is that it has two bells separated by an inflection point. For the implementation of this nozzle concept, more and more rapid research should be conducted as there have limited works on this concept. The present study addresses thermodynamic-parameters evolution such as Mach number, pressure and temperature distribution and so on. We have used ANSYS 17.2 fluent to analyze the nozzle geometry. The simulations were performed by using the k-epsilon turbulence model operating at pressure ratios (Chamber to ambient) of 50 and 100. Hybrid initialization is used for solution initialization. The result shows the criterion for the general approach to study the dual bell nozzles.

INCAS BULLETIN

Altitude-adapted nozzles are designed to facilitate flow adaptation during rocket ascent in the atmosphere, without requiring mechanical activation. As a consequence, the performance of the nozzle is significantly improved. The aim of this study is to develop a new profile of axisymmetric supersonic nozzles adapted at altitude (Dual Bell Nozzle with Central Body), which is characterized by an E-D nozzle as a basic profile. The performances obtained for this nozzle (E-D Nozzle) are then compared to those of a Plug nozzle. The E-D nozzle shows significant performance advantages over the Plug nozzle, including a 13.02% increase in thrust, knowing that the length of the E-D nozzle is half that of the Plug nozzle under the same design conditions. Finally, viscous calculations using the k-ω SST turbulence model were conducted to compare the performance of the dual bell nozzle with central body (DBNCB) and the E-D nozzle with the same cross-sectional ratio, and to assess the impact of nozz...

This project develops a computer code which uses the Method of Characteristics and the Stream Function to define high efficiency nozzle contours for isentropic, inviscid, irrotational supersonic flows of any working fluid for any user-defined exit Mach number. The contours are compared to theoretical isentropic area ratios for the selected fluid and desired exit Mach number. The accuracy of the nozzle to produce the desired exit Mach number is also checked. The flow field of the nozzles created by the code are independently checked with the commercial Computational Fluid Dynamics (CFD) code ANSYS-FLUENT. ANSYSFLUENT predictions are used to verify the isentropic flow assumption and that the working fluid reached the user-defined desired exit Mach number.

Progress in Flight Physics, 2013

The dual bell is a nozzle concept for altitude adaption. The §ow separates at the contour in §ection in sea level mode in a mainly controlled and symmetrical way, reducing the side load generation and increasing the thrust. The transition to altitude mode is reached when the §ow suddenly attaches to the extension for an improved altitude thrust. The conditions of this transition and its evolution are the key for the study of dual bell nozzles. For a better understanding of the §ow behavior, a two-dimensional (2D) subscale dual bell model has been designed and tested at the German Aerospace Center (DLR). The tests were divided into two campaigns and performed under cold and hot §ow conditions. The evolution of the shock system at the in §ection during the transition was observed using schlieren optics. The planar nozzle was tested under various conditions in pressure and temperature. Both test campaigns have been recalculated in cooperation with Astrium. Numerical and experimental results are presented.

2021

: Now the world is moving closer to the other planet. As we are searching for the new planets for living we had found that rockets are the only way capable to take the peoplefrom earth to the different planets, so scientist and engineers are focusing more on newrocket design which will be more efficient and more powerful in future, for example SpaceXcompany have rocket model SN8 which have ability to take the humans to the mars. Inrockets, the nozzle used for exhaust the gases at high speed which produced by thecombustion of propellants. Today we have different type of rocket nozzle like conical, bellor convergent divergent nozzles. In this paper we will discuss about the convergent anddivergent nozzle design with varying inlet and throat area or throat area ratio and will seethe variation in aerodynamic parameters and analyze all three designs on the ANSYSsoftware which is computational fluid dynamic software. In rockets, convergent divergentshape is mostly used as nozzle which is ...

IRJET, 2022

Rocket nozzle is a propelling device used in rocket engines to expand and accelerate the combustion gases produced by burning propellants. Nozzle design is an iterative procedure in which aerodynamic, thermodynamic, structural and fabrication consideration are handled within the constraint to produce a preliminary nozzle design. The structural design objective of nozzle is to verify the sustainability of the nozzles' internal contour under such loads and to limit the stress generated in the structure to a suitable limit. The basic purpose of this study is to understand the effect various structural and thermal stresses and strains developed on the nozzle geometry. Nozzle geometry is one of the most important factors to understand the performance of a rocket. A poor nozzle geometry may result in poor performance of the rocket. In this paper we have designed a bell nozzle according to G.V.Rao method and have studied the effect of the forces on the contour of the nozzle.. The same atmosphere has been simulated in Ansys 2021 R2 Student version and the behavior was studied. The structural failure of rocket nozzle may occur if the stress exceeds the permissible limits. The aim of this study is to develop such a nozzle which is effective under extreme loads and has the capability to resist such loads

IRJET, 2020

A nozzle is a very essential device that is used to control character of the fluid. The main purpose of the nozzle is to increase the velocity in one way or another. De Laval nozzle is a converging-diverging nozzle which has the ability to convert the chemical energy (high pressure) into kinetic energy (high velocity and low pressure). De-Laval nozzle has mainly 3 parts such as throat, diverging part, and converging part. Expansion in C-D nozzle has been studied and analyzed by experimentation moreover as numerically by numerous researchers with an objective to optimize the performance beneath given conditions. Within the gift work, supersonic flow through the rocket nozzle has been simulated mistreatment numerical methodology. The analysis has been performed keeping the same input and according to the shape of the nozzle. Our objective is to investigate the best suit nozzle which gives high exit velocity among the different cross-sections considered. The main aim of this paper is to a proper comparison with theoretical data to determine the behavior of fluid during the movement of fluid inside the nozzle. Therefore CFD analysis is being done using ANSYS 16. The paper contains a proper analysis of the convergent-divergent nozzle. Analysis of Mach number and velocity is done inside the nozzle