Supersonic Nozzle Research Articles

Convergent Divergent Nozzle Design and Analysis to Increase Working Effectiveness

Abstract: Our project's major goal is to develop and examine a Convergent- Divergent rocket nozzle in order to lower nozzle costs. Here, convergent divergent nozzle uses an alternative material. The design is based on earlier designs that served as a guide for our own. A nozzle is a crucial component that merits consideration in this era of expanding rocket propulsion for a variety of uses, including the launch of satellites into space or human missions. With this in mind, a fundamental design is created utilising the understanding of compressible flow, and the resulting thrust is estimated. use the layout established by hand computations. Utilising the ANSYS Fluent programme, the work is done in, the calculations and results are validated.

Effect of Cavitating Hydraulic Elements on Pump Characteristics

The effective and reliable performance of any pump can be significantly impacted by the piping system design. One of the essential points is the pump suction pipe. Poor design and dimension of the suction piping can lead to cavitation in the pump which affects its head and efficiency. The primary objective is to reduce the hydraulic losses of the suction piping in order to maintain a Net Positive Suction Head required by the pump. Suction piping is recommended to be short and straight, and branch connections, valves and elbows should be avoided, which is not always possible. In addition, cavitation can occur in the actual hydraulic elements installed on the pump suction. This work is focused on the investigation of cavitating hydraulic element in the suction pipe on the pump performance. A converging-diverging nozzle with a circular cross-section was used for this purpose. A straight pipe segment of constant diameter and the same length was used for comparison. Both elements were characterized by the loss coefficient and the cavitation number. Their influence on the pump head and the Net Positive Suction Head Available (NPSHA) was investigated.

Numerical analysis on the effect of passive control geometry in supersonic jet mixing enhancement

Abstract This paper presents the numerical analysis of a convergent-divergent circular nozzle with the exit Mach number of 1.69 with and without passive control at the exit. The passive control method opted for this analysis was inward and outward ascending triangular protrusion. This paper explores the influence of the passive control geometry and its blockage area concerning the nozzle exit. The nozzle pressure ratio (NPR) used for carrying out the flow analysis were 3, 4.932, and 6. Two different inward and outward protrusions were used with a height of 1.5 mm and 3 mm. From the results, the potential core length of the protrusion 1.5 mm height was not much changed in the both outward and inward cases. But when the height of the protrusion was increased to 3 mm, there was a noticeable core length reduction at all NPR but with different cases. At the NPR of 6, the potential core length of the inward protrusions 3 mm was reduced by 44 % compared to the plain CD nozzle.

Experimental and Theoretical Investigation of the Reaction of NH2 with NO at Very Low Temperatures.

The first experimental study of the low-temperature kinetics of the gas-phase reaction between NH2 and NO has been performed. A pulsed laser photolysis-laser-induced fluorescence technique was used to create and monitor the temporal decay of NH2 in the presence of NO. Measurements were carried out over the temperature range of 24-106 K, with the low temperatures achieved using a pulsed Laval nozzle expansion. The negative temperature dependence of the reaction rate coefficient observed at higher temperatures in the literature continues at these lower temperatures, with the rate coefficient reaching 3.5 × 10-10 cm3 molecule-1 s-1 at T = 26 K. Ab initio calculations of the potential energy surface were combined with rate theory calculations using the MESMER software package in order to calculate and predict rate coefficients and branching ratios over a wide range of temperatures, which are largely consistent with experimentally determined literature values. These theoretical calculations indicate that at the low temperatures investigated for this reaction, only one product channel producing N2 + H2O is important. The rate coefficients determined in this study were used in a gas-phase astrochemical model. Models were run over a range of physical conditions appropriate for cold to warm molecular clouds (10 to 30 K; 104 to 106 cm-3), resulting in only minor changes (<1%) to the abundances of NH2 and NO at steady state. Hence, despite the observed increase in the rate at low temperatures, this mechanism is not a dominant loss mechanism for either NH2 or NO under dark cloud conditions.

Development of Composite Ablative Liners for Solid Rocket Motor Flex Nozzles

Solid Rocket Motor generates high thrust by accelerating high pressure gases to supersonic velocities in convergent divergent nozzle, thus converting pressure energy to kinetic energy of propulsion. As exhaust gas from chamber is of high temperature, the structural steel members of nozzle should be protected from hot gases by highly erosion resistant thermal liners. For this purpose, ablative composite liners made up of Phenolic resin matrix based combined with reinforcement material like carbon fabric is extensively used [1]. Divergent being largest component and contributes more to nozzle weight, the thickness of liner should be as least as possible at the same time; it should be more erosion resistant. The erosion resistant due to hot gases can be increased by fabricating the liner in such a way that the flame only touches the edge of the composite ply of liner and liner has more density. This can be achieved by tape winding of composite prepreg tapes at Zero degrees on tapered metal mandrel using tape winding machine followed by Autoclave curing [2]. This paper gives the details of prepreg, Tape winding, Autoclave Curing and NDT of ablative liner.

Numerical investigation of wide continuous particle size distribution on the supersonic powder loading oxygen jet

Supersonic oxygen-powder jet injection has spanned wide range of operations in chemical engineering. However, the ubiquitous polydispersity of solid powder known to exert different flow behavior than the monodisperse counterpart has not been revealed. In this work, numerical simulation of the supersonic oxygen-powder jet injection via the Laval nozzle is performed under the Eulerian-Lagrangian framework to explore the impact of wide continuous size distribution of solid phase on the gas-solid hydrodynamics. Specifically, the gas phase is solved using the Eulerian method, while the particle motion is tracked under the Lagrangian framework. The numerical model is well validated with the experimental measurements. The results reveal that the blending of particles restricts the gas phase expansion, leading to the obvious reduction of gas velocity and increase of gas temperature. Additionally, a narrow particle size distribution (PSD) width corresponds to a higher proportion of large particles, inducing stronger vortices and hindering gas phase expansion. With regard to solid phase, the penetration ability of particles is significantly enhanced within the supersonic gas flow by accelerating the particle velocity to about 300 m/s. Furthermore, particles with wider PSD exhibit increased sensitivity to interphase interaction, particle-particle collisions and lift forces, resulting in higher velocities, lower temperatures along the axial direction and greater dispersion along the radial direction. Lastly, the interphase heat transfer mainly occurs in the convergent section, divergent section, and one nozzle length downstream from the nozzle exit. The findings obtained in this study offer valuable insights for industrial applications.

Four-way coupled Eulerian-Lagrangian study of phase interaction mechanism in the supersonic gas-solid two-phase flow

Supersonic gas–solid jet injection has received much attention in many industrial applications such as pneumatic conveying, powdered drug delivery, steel refining process and thermal spray coating, but it is still a challenging topic due to the complex interphase interaction in compressible flows. In this work, supersonic gas–solid two-phase flow is numerically studied under the Eulerian-Lagrangian framework. After the model validation with the experimental measurement, the inherent mechanism of supersonic gas–solid flow under the conditions of different powder feeding rates and particle diameters is explored. The results demonstrate that increasing the powder feeding rate leads to the reduction of the axial velocity and penetration ability of the particles. Especially when powder feeding rate increases to 10 kg/s, serious blockage occurs in the nozzle divergence section and the conventional supersonic flow characteristic in Laval nozzle has been substantially changed. Moreover, particle diameter largely determines the dynamic and thermodynamic characteristics of the particles. Small-diameter particles exhibit better followability to the gas phase and large-diameter particles exert non-negligible impact on the gas flow, mainly reflects in weakening the expansion ability of the gas phase. The results obtained in this work provide meaningful insight for understanding the flow characteristics of supersonic gas–solid flow and benefit the operating parameters selection in industrial applications.

STUDYING THE POSSIBILITY OF USING COHERENT TYPE NOZZLES FOR BOF BLOWING AT THE GAS DYNAMIC SIMULATION STAND

Introduction. The BOF technology is the leading one in the production of structural steel due to its undeniable advantages.Problem Statement. In the conditions of most Ukrainian converter shops, when the blowing parameters change significantly during the campaign (temperature of the lining, dimensions of the workspace, quality of scrap metal, temperature and composition of iron), and the bath is blown at a constant flow rate with conventional Laval nozzles, sometimes it is impossible to ensure a stable purging process with high rate of post-combustion of CO up to CO2. Therefore, one of the main problems of oxygen conversion is the improvement of the designs of blowing devices, in particular, the nozzles.Purpose. The purpose of this research is to study the possibility of using nozzles of the coherent type for the top oxygen blowing of the converter.Material and Methods. In the research, we have used samples of coherent-design laboratory nozzles having different central part-to-periphery ratio under fixed equal general conditions of jet output (percentage of the annular gap to the total area of the nozzle, %: 75, 65, 50, 45, 35, 25). They have been studied by calculating the jet momentum, through weighing and taking shadow shots when the gas flow velocity reaches 2 M. The results have been compared with those for the cylindrical nozzle.Results. When the gas is supplied at 2 M, the coherent-type nozzles with a fraction of the outer part of 65—75% contribute to the formation of 1.5—1.6 times wider jets as compared with the cylindrical nozzle, with a multinode structure. It helps to increase the jet momentum by 45—55%.Conclusions. The design of a coherent type nozzle with an outer part share of 75% can be recommended to be used as the second tier or the second level nozzles of the top oxygen lance for post-combustion in an oxygen converter due to an increase in the surface area of the jet contact. The efficiency of post-combustion of CO from waste converter gases is expected to increase due to the increasing reaction surface area of additional oxygen jets.

Heat Flux Prediction in a Kerosene Fuelled Scramjet Combustor Through Cfd

Thermo-structural design of high speed propulsive systems require heat transfer as an input. Nonreacting and reacting flow simulations are carried out to predict the heat transfer characteristics of scramjet combustor using commercial software. The software employs finite volume method to solve 3-D RANS equations along with SST-kω turbulence model and infinitely fast chemistry. The flow through a convergent-divergent nozzle is taken as validation test case and very good match is obtained between computed heat flux and experimental data. It is observed that minimum 10 micron 1st grid spacing is required to predict wall heat flux accurately and grid independence of heat flux data is demonstrated. Heat transfer coefficient is independent of various isothermal walls and computed heat fluxes are higher at combustion intense zone behind fuel injection struts.

Numerical study on the influence of nozzle divergence half angle on thrust oscillation characteristic of underwater jet power

Underwater rocket propulsion is increasingly used in advanced marine vehicles that may be subject to supersonic gaseous jets while submerged. This work investigates the influence of supersonic nozzle divergence on the multi-flow field evolution process and the thrust oscillation characteristics by multiple numerical simulations using a VOF multiphase flow model. Four nozzle divergence half angles are taken into consideration. The analysis indicates that the thrust rises sharply at nozzle closure opens, then rapidly decreases and follows another rise. The thrust oscillates at high frequencies. As a result, increase of the nozzle divergence half angle leads to the size decrease of flow bubbles but does not affect the changing trends of the thrust. Increase of the nozzle divergence half angle leads to a reduction of the frequency of the thrust oscillations.

CFD Analysis of Over-Expanded Flow in Convergent Divergent Nozzles

The classical one-dimensional inviscid theory does not reveal the complex flow features in an over-expanded nozzle accurately. The code Fluent has been used to simulate the viscous fluid (air) flow passing through three different 2-D Convergent-Divergent (C-D) nozzles for nozzle pressure ratios (NPR) corresponding to over-expanded flow. The steady state RANS equation with five different turbulence models has been simulated for turbulence model study. Two different types of boundary layer grids: grid1 (y&lt;sup&gt;+&lt;/sup&gt;=1) and grid 2 (y&lt;sup&gt;+&lt;/sup=50) have been simulated. Shear Stress Transport k-w (SSTKW) turbulence model with grid 1 has been chosen for turbulence modeling. Both inviscid and viscous flows have been simulated. The converged solutions captured asymmetric lambda shock in all the three nozzles at higher NPRs for viscous flows. It also predicted aftershock and flow separation depending upon NPR. The shock wave angle of the incident and reflected shock generally reduces with increase in NPR for NPR£1.92. The thrust co-efficient of all the theoretical, predicted inviscid and predicted viscous solutions reduce with increase in NPR upto a certain value of NPR and then starts increasing. The predicted viscous results (shock structure, shock location, size of normal shock, aftershock and asymmetric lambda shocks) are close to the experiments in most of the cases. The aftershock phenomenon provides dual mode flow at the exit of the nozzle.

Techniques of Fluidic Thrust Vectoring in Jet Engine Nozzles: A Review

Thrust vectoring innovations are demonstrated ideas that improve the projection of aerospace power with enhanced maneuverability, control effectiveness, survivability, performance, and stealth. Thrust vector control systems following a variety of concepts have been considered for modern aircraft and missiles to enhance their military performance. Short Take-off and Landing (STOL) and control effectiveness at lower aircraft speeds can be achieved by employing Fluidic Thrust Vectoring Control (FTVC). This paper summarizes a range of ideas for FTVC that have been designed and tested both computationally and experimentally to determine the thrust vectoring performance of supersonic propulsion system nozzles. The conventional method of thrust vectoring involves mechanical means to deflect the direction of flow of the exhaust gases, whereas the most recent method involves fluidic-based thrust vectoring techniques. Fluid-based thrust vectoring has the advantages of simplicity and low weight over mechanical-based thrust vectoring, which has complex geometry and adds extra weight to the aircraft. The fluidic vectoring control nozzles are divided into seven categories: shock vector, bypass shock vector, counterflow, co-flow, throat skewing, dual throat, and bypass dual throat nozzle control. This paper provides a summary of each fluidic thrust vectoring technique with its characteristics, design, classification, and different operational criteria developed to date and compares the intrinsic characteristics of each technique. Based on the present literature, it is concluded that among all the fluidic control techniques, the bypass dual-throat nozzle control can achieve better thrust vectoring performance with large vector angles and low thrust loss.

High Temperature Gas Effect on the Supersonic Flow With Application in Nozzles

This work is to develop a new numerical computational program to determine the effect of using the gas of propulsion at high temperature on the calculation of the thermodynamic and geometric parameters, and application in supersonic nozzle divergent. The used selected gases are the H2, O2, N2, CO, CO2, H2O, NH3, CH4 and air. All parameters depend on the stagnation temperature, supersonic Mach number and the used gas itself. The specific heat at constant pressure change with the temperature and the selected gas. The gas is still considered perfect. It is calorically imperfect and thermally perfect below the threshold of the molecules dissociation. A calculation of the error between the parameters of different gases with air is done for purposes of comparison.

Design and Computational Analysis of an Axisymmetric Contoured Supersonic Propulsion Nozzle

The design of supersonic axisymmetric nozzles to a required exit Mach number necessitates applying the Method of Characteristics (MoC) that reduces the partial differential equations system of hyperbolic form governing such internal flow-fields to two ordinary differential equations known as the characteristic and the compatibility equations. These relationships are then transformed into finite difference equations and solved using an appropriate predictor-corrector algorithm.The present study applies the MoC to the design of a contoured nozzle that accelerates the combustion gases to supersonic velocities. The selected configuration has a throat constituted of two circular arcs with the one downstream attached to a 2nd-order polynomial profile at the attachment point. The solution, in terms of the static pressure along the centerline and the wall is obtained. It was found that the flow expands gradually without any instability or possibility of shock waves. A gradual expansion represented by a decrease in pressure is noticed immediately downstream of the throat, the flow tending to expand gradually from the throat to the exit. Along the wall, the expansion is important immediately downstream of the throat while it tends to stabilize downstream to reach the ambient pressure at the outlet. In terms of performance, the thrust coefficient developed shows the great expansion process within the divergent supersonic section. The configuration is also found to develop a great specific thrust.

Research on non-equilibrium condensation of supercritical carbon dioxide in sCO2 power systems

Based on the consideration of sustainable development and energy efficient transformation, people propose using renewable energy to upgrade traditional power generation systems. The supercritical carbon dioxide (sCO2) Brayton cycle has a great utilization potentiality in thermodynamic systems, such as solar thermal power generation systems. When the CO2 fluid flows into the compressors of sCO2 power systems, there is a risk of non-equilibrium condensation due to local expansion and acceleration, which seriously threatens the stability of the whole system. The convergent-divergent nozzle is usually used to study non-equilibrium condensation. In this paper, the wet steam model is used to simulate the non-equilibrium condensation of the CO2 fluid near its critical region in a convergent-divergent nozzle. The phase change model and the thermophysical equation of state are verified by experimental data. The non-equilibrium condensation process is analyzed, and the droplet nucleation process and droplet growth process are described. Non-equilibrium condensation releases the latent heat and forms a condensation shock wave. The influences of the shock wave effect on temperature, pressure, and other parameters are discussed. The initial condensation position and critical subcooled temperature under different inlet conditions are analyzed.

Effect of Relative Jet Temperature in Supersonic Dual-Impinging Jets

Short takeoff and vertical landing aircraft configurations involve multiple jets that impinge onto the deck surface in tandem and lead to several adverse effects. This study reports on the experimental characterization of supersonic dual-impinging jets by systematically varying their relative jet temperature. A sonic converging and Mach 1.5 converging–diverging (CD) nozzles are employed. The expansion ratio of the converging nozzle is maintained at 0.96, 1.19, and 1.59, and the CD nozzle is operated at a fixed nozzle pressure ratio of 3. The temperature ratio of the jet from the CD nozzle is varied from 1.0, 1.3, and 1.7. For a fixed momentum of the jet pair, an increase in jet temperature intensified the nearfield noise and unsteadiness on the impingement surface. At short impingement heights, resonance in the heated jet was the primary source of unsteadiness. At a fixed impingement height, an increase in jet temperature led to a systematic increase in tonal frequency, while jet instability mode shapes were retained. Furthermore, the mean flowfield of sonic jet and fountain regions remain unaffected, and an increase in supersonic jet velocity is observed. This is also accompanied by an increase in unsteadiness in the fountain upwash.

Numerical model of predicting surge boundaries in high-speed centrifugal compressors

A numerical model of the whole compression system is established in this paper. The introduction of the Laval nozzle and opening boundary methods adaptively simulate the physical fluctuating boundary conditions during the surge without any artificial hypothesis. Based on the model, the steady simulation method has the capacity to well predict the low-order systematical oscillations during the surge by monitoring flow parameters on several representative surfaces. The surge boundaries of a high-speed centrifugal compressor, including the mild surge and the deep surge, are predicted based on the current numerical model in different flow regimes. The discrepancies of the mild surge boundary between experimental data and numerical predictions are within 5% in the transonic regime, but within 0.5% in the subsonic and supersonic regimes. The sensitivities of the mild surge to the throttle opening degree differ much in different flow regimes: the highest is in the transonic regime and the lowest is in the supersonic regime. In the supersonic regime, there exist various mild surges in a wide range of throttle opening degrees and an unstable equilibrium point (UEP) which is the most typical characteristic of the two-regime surge. To the best knowledge of the authors, it is the first time that all the oscillation characteristics of various mild surges and the existence of UEP in the supersonic regime are well predicted by one numerical method.

Effect of Supersonic Oxygen Lance on Post-Combustion in Converter Steelmaking Process – Experiment and Analysis with Converter Simulator

Employing post-combustion technology in the converter, using the sensible heat of the hot metal and the oxidation reaction heat as a heat source, is known to compensate for insufficient heat in the converter process. However, most studies on post-combustion have been conducted using subsonic nozzles, whereas actual converter processes use supersonic nozzles. Therefore, research on the combustion behavior of supersonic jets is needed. In this study, experiments and analyses were conducted using a converter simulator and a supersonic nozzle to investigate the effect of nozzle height on the post-combustion behavior. The reaction was set to complete combustion, with an O2gas flow rate of 150 L/min blown through the upper lance and a CO gas flow rate of 300 L/min blown at the bottom of the simulator to represent the surface of the molten metal. The combustion reaction of CO gas was calculated to be rate-controlled by reactant mixing. The nozzle heights were set to 250, 380, and 530 mm from the surface of the molten metal. Post-combustion analysis showed that the lowest gas velocity was observed under the condition of the highest nozzle height of 530 mm, and the high temperature and reaction zones were widely distributed in the lower region. Therefore, to facilitate heat compensation to the molten metal, it is necessary to control the gas velocity of the molten steelgas interface slowly.

Effect of relative humidity on the nozzle performance in non-equilibrium condensing flows for improving the compressed air energy storage technology

Compressed air energy storage (CAES) is now becoming the focus of a lot of research as it offers broad application possibilities and enormous economic benefits in terms of environmental protection and life with low-carbon emissions. The compressor performance is closely related to energy storage efficiency in CAES. Considering the significant role of water components inside the flow of the compressor, the flow mechanism in transonic with non-equilibrium condensation should be explored in detail. First, a blend condensation model is presented with the effect of the entire Knudsen number range on droplet growth, to explore condensation flow characteristics more clearly. Moreover, the influence of relative humidity (RH) on the nucleation and droplet growth and condensation shock wave is analysed with the blend model. Finally, flow loss is calculated in the de Laval nozzle, and the direction to optimize the compressor efficiency is indicated by considering the RH conditions and wall curvature arcs. The contribution of these factors to the flow loss deserves careful consideration. The analysis conducted in the paper shows the effect of relative humidity on the nozzle, and the conclusions obtained provide meaningful reference for improving the performance of compressors used in the CAES process in the future.

Numerical simulation on effects of augmentation in temperature of inlet steam on wet steam flow in supersonic nozzle: energy and exergy analysis

Numerical simulation on effects of augmentation in temperature of inlet steam on wet steam flow in supersonic nozzle: energy and exergy analysis