Oscillatory combustion representative of thermo-acoustic instability in liquid rockets is simulated by experiment and LES calculation to investigate the flame behavior in detail. In particular, we focus on how the velocity and pressure fluctuations affect the behavior of the dense oxygen jet, or ‘LOx core’. The test case investigated is a high pressure, multi-injector, oxygen-hydrogen combustor with

Ceramic microthrusters with an embedded Pt resistive heater, two temperature sensors, and a Pt or Ag catalytic bed were made of high-temperature co-fired alumina ceramics. To increase the surface area by a factor of 1.21, and so the catalytic effect, the Pt catalytic bed was made porous by mixing the Pt paste with 15–20vol.% graphite sacrificial paste before screen printing it. Ag was in-situ electroplated

Contra-rotating turbines offer enhanced performance over their conventional co-rotating configurations. In addition, vaneless contra-rotating turbine stages offer lesser stage length along with improved performance. Contra-rotating turbines with a vaned LP stages offer a controlled work-split between the stages over a wider range of operating conditions by maintaining inlet swirl to the second rotor

MI-Jet or medium independent jet engine is a new conceptual design which can be used in any gaseous atmosphere or in any planets with an ISP greater than that of the existing rocket engines. MI engine's thermodynamic concept could be utilized to develop turbojet, ramjet and scramjet engines that can operate in Martian environment with higher ISP. The same concept could be extended for the development

This study focuses on the combined impact of heat source/sink and chemical reaction on slip flow of micropolar fluid through a permeable wedge in the existence of Hall and ion-slip currents. The governing highly non-linear PDEs were altered into a set of non-linear coupled ODEs by using similarity transformations. Differential transformation method (DTM) has been implemented in transformed ODEs equations

In this study, a two-dimensional boundary layer flow of steady incompressible nonlinear convective flow of Oldroyd-B fluid over a nonlinearly stretching sheet with Cattaneo-Christov heat flux model and heat generation or absorption is examined. The governing equations of the boundary layer flow which are highly nonlinear partial differential equations are converted to the ordinary differential equations

Rotating machinery is an essential and crucial component of numerous mechanical systems in modern industries, transport vehicles, and in several other applications. Excessive vibrations on rotating equipment due to multiple faults may cause catastrophic failure in machines and lead to hazardous accidents. So, there is a need for perceiving the dynamic nature and identifying the faults for the safe

A numerical investigation is presented to show the effects of thermo-diffusion on the hydromagnetic stagnation-point flow of Sisko nanofluid over a linearly stretching sheet by considering viscous dissipation and Joule heating with suction/injection. A suitable set of similarity transformations is considered in order to convert the basic partial differential equations into a set of coupled nonlinear

During the last years, several thrust control systems of aerospace rocket engines have been developed. The fluidic thrust vectoring is one of them; it is simple in design and offers a substantial gain in weight and in performance. Numbers of studies that deal with this subject are conducted on cold gas flow model. It can be expected that the thermophysical properties of the gases may affect considerably

Present article aims to discuss the characteristics of Casson type nanofluid maintained to flow through porous medium over non-linear stretching surface in the perspective of heat and mass transfer developments. A Casson type incompressible viscous nanofluid passes through the given porous medium via Darcy-Forchheimer relation. Slip boundary conditions are used for velocity, temperature and concentration

The objective of the present work is to analyze the flow, heat and mass transfer characteristics in a thin nanofluid film over a heated stretched sheet in the presence of a non-uniform heat source/sink and thermal radiation. Similarity variables are used to transform the partial differential equations into a system of ordinary differential equations. The resulting system of nonlinear ordinary differential

This study investigates the steady stagnation point flow and heat transfer passes a horizontal shrinking permeable cylinder. The free stream velocity and the prescribed surface heat flux are assumed to vary linearly with the distance from a fixed point on the cylinder. The partial differential equations governing the flow and heat transfer are transformed into a system of ordinary differential equations

In this article, the variation of temperature distribution and fin efficiency in a porous moving fin of rectangular profile is studied. This study is performed using Darcy's model to formulate the governing heat transfer differential equation. The approximate analytical solution is generated using the variational iteration method (VIM). The power series solution is validated by benchmarking it against

This study analyzes the second law of thermodynamic for entropy generation in an irreversible hydromagneto-micropolar flow system with non-homogenous heat generation. The non-symmetric microstructure fluid flow past a stretching sheet with saturated porous non-linear media under magnetic field influence. Ignoring the fluid particle deformation, the microstructure is assumed rigid with the viscous suspended

An investigation was performed to determine the pressure transient levels and time required to reach pressure equilibrium in a regulated liquid propulsion system due to the priming of a propellant tank during system initiation. An experimental fluid flow test setup was designed and fabricated using a pressure vessel to house distilled water as a propellant simulant for liquid hydrazine and high-pressure

The present study introduces an innovative aerodynamic redesign of an axial flow fan based on constant diffusion factor and radial equilibrium. All input design parameters such as mass flow rate, hub to tip ratio, aspect ratio, tip diameter and angular velocity are taken from NASA Rotor 67 as a conventional axial flow fan. A computer program is developed to extract the three-dimensional geometry of

Combustion process inside kerosene-GOx rocket combustor with kerosene film cooling is studied, and a modeling approach is proposed. The paper suggests to use the Lagrangian particle tracking technique to model fuel film behavior while the continuous fluid is simulated via the Navier-Stokes system of Favre-averaged equations. The approach is validated over the 12 experimental regimes by the criterions

Transmission error (TE) in geared rotors is a predominant source of inherent excitation at the pitch point of the gear meshing. In this paper, a transverse vibration analysis is presented to study the effect of TE on geared rotors. Due to asymmetry in the TE, it is expected to have both forward and backward whirls excited during rotor whirling, which could be used for its detection. This aspect has

A numerical simulation of a single cylinder research diesel engine fuelled by natural gas and diesel oil in dual fuel mode was conducted to test the reaction mechanism presented by Li and Williams in Ref. [1] for methane ignition. The mechanism made of only 9 reactions can represent a good compromise between reduction of computational time and accuracy of results. Simulations reproduce test cases previously

Aircraft emissions contribute to global climate change and regional air pollution near airports. Understanding the formation and the transformation of emissions in the aircraft engine is essential to properly quantify the environmental impact and air pollution. However, precise investigation of chemical process in the turbine is challenging because of the complexity of the transformation process in

Interaction between fuel and air in a combustion chamber is one of the main drivers of the mixing process. Experimentally, flow visualizations are limited by high droplet density in the spray. Numerically, the ability of large eddy simulations (LES) to resolve large scales of flow offers good perspectives on capturing flow structures issued from the interaction between the Lagrangian (fuel droplets)

Both internal and external damping are concurrently present in a rotor system. However, the internal damping that originates from various sources often leads to instability in the rotor system, and hence its accurate estimation is crucial. The goal of the present paper is to distinctly estimate both external and internal damping in a Jeffcott rotor containing transverse crack. The modelling of the

The flow through an axisymmetric supersonic mixed-compression air inlet has been simulated numerically to investigate the effects and the necessity of the three-dimensional (3D) modeling in comparison with the axisymmetric one. For this purpose, a supersonic inlet has been simulated numerically via axisymmetric and 3D CFD solvers, using the steady state Reynolds-averaged Navier-Stokes equations along

The analysis of the scavenging process in two-stroke engines is important in terms of achieved performance and emission of toxic substances. The amount of mass of air used for the scavenging process and the amount mass of gas retained in the cylinder affect engine efficiency. When designing two-stroke engines, the most efficient charge exchange process defined by the scavenging efficiency parameter

The aim of present study is to investigate the burning rate, ignition delay, and flame characteristics of ammonium perchlorate (AP)-hydroxyl terminated poly-butadiene (HTPB) [AP/HTPB] based composite propellants (CSP's) in sub-atmospheric pressure regimes (13 kPa–100 kPa). Several fuels and catalyzed were used to evaluate their effects on the combustion characteristics of AP based propellants in sub-atmospheric

Research interest has been growing in recent years in supersonic transport, particularly supersonic propulsion systems. A key component of a commonly studied propulsion system, ramjets, is the air intake. For supersonic propulsion systems a major factor in the overall efficiency is the intake pressure recovery. This refers to the ratio of the average total pressure after the intake to that of the freestream

The linear model of the aero gas turbine is effective in a small application range. According to this problem, the identification method for parameter uncertain linear model of aero gas turbine proposed. The identification problem is solved by calculating nonlinear programming. Considering the parameter uncertainty of the model is the critical point of this research during the optimization process

The primary focus of the present study is to investigate the impact of anti-vortex holes design on the film-cooling performance in a film-cooled rotor blade model using the large eddy simulation method (LES). One row of the film holes was positioned on the pressure surface of the rotor blade. This row had three cylindrical holes (the main hole in the present study) with a diameter (D) of 4 mm and a

The present pagination reports both Brownian diffusion and thermophoresis aspects subject to magnetohydrodynamic Williamson fluid model. Assuming the flow is unsteady and blood is treated as Williamson fluid over a wedge with radiation. The governing equations are transformed into ordinary differential equations by using similarity variables. The numerical solutions of the transformed governing equations

A numerical simulation is presented to investigate the effect of an exponentially varying magnetic field on three dimensional flow of Zinc Oxide-Society of Automotive Engineers 50 nanolubricant (ZnO-SAE50nano-lubricant) past a stretching sheet. Subsequently the impact of homogenous and heterogeneous reactions on the flow of nanolubricant concerned has also taken into account. The study has been strengthened

A series of tests was conducted to unlock the potential application of MgO/water-EG (ethylene glycol) nanofluids (NF) in a double-pipe heat exchanger (HEX). The overall heat transfer coefficient (HTC), the inlet temperature of the working fluid, the fluid pressure drop (FPD), friction factor (FF) and the hydraulic performance index of the NF within the HEX were experimentally measured. Fouling of nanoparticles

In a gas turbine power plant, the lubrication oil must be hot enough for the turbine start-up where the unit is in standstill mode. Currently, the strategy to heat the lubrication oil of ANSALDO V94.2 gas turbine power plant is operating the units in turning gear mode or interval mode. However, these strategies cause to suffering the power plant from high power consumption rate and aging. In this study

Aeroelastic vibration problems are commonly found in modern compressors operating in off-design conditions. Large amplitude vibration could lead to high cycle fatigue (HCF) of blade and usually occurs in front stages of axial compressors. In this study, the influence of tip gap size on aeroelastic stability is analyzed in a 1.5 stage compressor with an in-house fluid-structure interaction code. A three-dimensional

In this article, laminar convective heat transfer of a confined slot impinging jet with nanofluid has been numerically investigated over Reynolds number ranges of 200–1000. Two circular ribs are mounted on the lower-target surface: one rib located right the stagnation point and another one located on the left of the stagnation point. SiO2-water nanofluid with nanoparticles volume fraction ranging from

The current article presents conceptual, preliminary and detailed aero-thermal redesign of a typical high pressure turbine nozzle guide vane. Design targets are lower coolant consumption, reduced manufacturing costs and improved durability. These goals are sought by 25% reduction in vane count number and lower number of airfoils per segment. Design challenges such as higher airfoil loading, associate

The present work describes similarity solution to a general scheme for the wall jet flow of nanofluids, accounting both the similarity branches (say upper and lower), allowed with respect to the suction and moving wall conditions in the context of Glauert type e-jets. Before proceeding with this, a spatial stability analysis is performed to check the stability of the similarity modes. Results indicated

In the present article, we perform the second law analysis of classical Blasius flow accounting the effects of nonlinear radiation and frictional heating. The two-dimensional boundary layer momentum and energy equations are converted to self-similar equations using similarity transformations. The set of resultant ordinary differential equations are solved numerically. The numerical results obtained

The influence of elasticity on peristaltic transport of Herschel-Bulkley fluid in a tube of non-uniform cross-section is investigated. The exact solutions for flow quantities such as velocity, stream function, pressure gradient, and volume flow rate are derived. The relationship between flux and pressure difference is discussed. The effects of different pertinent parameters on variation of flux along

In this paper, stagnation point region (suspended with nanofluid and microorganisms) is examined subjected to velocity and thermal slips. The flow is assumed to be flowing across an exponentially stretching flat surface under magnetic field environment. Governing transport equations (framed under Buongiorno's model) are converted into self-similar form through suitable unsteady exponential similarity

Wave rotors are rotating equipment designed to exchange energy between high and low enthalpy fluids by means of unsteady pressure waves. In ground power plants, they can be used as topping devices to existing gas turbines aiming to improve their performance characteristics. A four-port wave rotor is an attractive configuration to be integrated into the gas generator of a two-shaft gas turbine, typical

In the present paper, unsteady natural convective heat transfer flow inside a square enclosure filled with nanofluids containing magnetic nanoparticles using nonhomogeneous dynamic model is investigated numerically. The horizontal top wall of the enclosure is considered a colder wall and the bottom wall is maintained at uniform temperature whereas two other vertical walls of the cavity are thermally

A theoretical study is conducted for magnetohydrodynamic pumping of electro-conductive couple stress physiological liquids (e.g. blood) through a two-dimensional ciliated channel. A geometric model is employed for the cilia which are distributed at equal intervals and produce a whip-like motion under fluid interaction which obeys an elliptic trajectory. A metachronal wave is mobilized by the synchronous

The thermal and velocity slips of boundary layer of Williamson nanofluid over a stretching sheet are studied numerically. Buongiorno model is used to explore the heat transfer phenomena caused by Brownian motion and thermophoresis. Using similarity transformations, the governing equations are reduced to a set of nonlinear ordinary differential equations (ODEs). These equations are solved numerically

In this paper Carreau fluid is taken into account to study its peristaltic flow with Hall and ion-slip effects. The study is carried out in a wave frame of reference for both asymmetric and symmetric channel. Analysis of heat transfer is accomplished by taking the effects of viscous dissipation and ohmic heating into our consideration. Modeling of fundamental equations is followed by the construction

Conical plug nozzle and truncated conical plug nozzle are advanced rocket nozzles suitable for use as altitude compensating nozzles. In this study flow through the conical plug and truncated conical plug nozzles are numerically simulated to first validate with experimental data and then to compare the performance when a base bleed is introduced. The numerical analysis has considered two-dimensional

In this study, numerical analysis and optimization in a single and multiple walled carbon nanotube-water nanofluid filled lid driven cavity having an inner elliptic obstacle were performed by using finite element method and COBYLA optimization solver. The top wall is moving with constant speed and vertical walls are kept at constant temperatures. An optimal size of the inner elliptic obstacle was determined

The present article is concerned with the heat transfer of nanofluid saturated with porous medium sandwiched between clear viscous fluid filled in a vertical channel. The model is developed to analyze the behavior of nanofluids taking into account the solid volume fraction. The governing equations are obtained based on the Darcy׳s law for the porous medium and Tiwari and Das model to define the nanofluid

The investigation of closed form solutions for nonlinear evolution equations (NLEEs) is being an attractive subject in the different branches of mathematical and physical sciences. In this article, the enhanced (G′/G)-expansion method has been applied to find the closed form solutions for NLEEs, such as the simplified MCH equation and third extended fifth order nonlinear equations which are very important

Considering the self-ignition characteristic and C/H ratio, n-heptane and toluene (6:4 by mass) are chosen to constitute diesel surrogate fuel, and a reduced oxidation mechanism was developed. This mechanism was firstly validated by the combustion of diesel fuel in different oxygen concentrations within a constant volume vessel by high-speed photography. The simulated flame temperature distribution

Stimulated by thermal optimization in magnetic materials process engineering, the present investigation investigates theoretically the entropy generation in mixed convection magnetohydrodynamic (MHD) flow of an electrically-conducting nanofluid from a vertical cylinder. The mathematical model includes the effects of viscous dissipation, second order velocity slip and thermal slip, has been considered

The Institute of Gas Turbines and Aerospace Propulsion at Technische Universität Darmstadt conducts research projects in the field of “combustor turbine interaction” (CTI). This paper presents numerical studies on the interaction between novel combustion concepts and conventional “high pressure turbine” (HPT) stages. In order to obtain higher efficiency and reduce emissions of jet engines, it is necessary

This paper presents an analytical solution for natural convection flow in a vertical annulus due to time-periodic heating of annulus surfaces. Closed-form expressions for velocity, temperature, skin-friction, mass flow rate and rate of heat transfer which is expressed as Nusselt number are obtained by solving the present mathematical model after separating into steady component and periodic regime

In this article comparative analysis of various semi-numerical schemes has been made for the case of squeezing flow of an incompressible viscous fluid between two large parallel plates having no-slip at the boundaries. The medium of flow contains magnetohydrodynamic (MHD) effect and having small pores. Modeled boundary value problem is solved analytically using Optimal homotopy asymptotic method (OHAM)

Micropolar theories present an excellent mechanism for exploring new non-Newtonian materials processing provides a stimulating area for process engineering simulation. Motivated by area for process engineering applications, the present article presents the scope of finite element method in solving a mathematical model for magnetohydrodynamic, incompressible, dissipative and chemically reacting micropolar

Current study examines the combined effect of thermal radiation and velocity slip along a convective heated stretching sheet. magnetohydrodynamic (MHD) effect near the stagnation point is also under consideration. The main structure of partial differential equations attained in the form of momentum, energy and concentration equations. For a self-similar solution, the system of governing PDEs assimilated

This article studies effects of heat generation/absorption and chemical reaction on the unsteady magnetohydrodynamic (MHD) Casson fluid flow past over exponentially accelerated vertical plate embedded in porous medium. It is assumed that the bounding plate has ramped temperature with ramped surface concentration and isothermal temperature with ramped surface concentration. This phenomenon is modeled

A steady boundary layer flow over a porous flat plate has been considered in the present study. Mass transfer analysis with first order chemical reaction is also considered instead of heat transfer. The plate concentration is considered in the form of power law instead of taking constant. The governing PDEs are transformed into ordinary differential equations using similarity transformation and then

Experimental investigation has been done to evaluate the leakage performance of labyrinth seal for oil sealing on high-speed sealing test rig at different working and geometric parameters. Typical values of pressure ratio ranging from 1.0 to 2.0 were used and the rotating speed varied from 0 to 30,000 rpm. Dimensionless Taylor number was invited to response the effect of rotation. Oil was injected

Transition from laminar flow to turbulent flow is of great practical interest as it occurs in many engineering flows and often plays a critical role in aerodynamics and heat transfer performance of those flow devices. There could be many routes through transition, depending on flow configuration, geometry and the way in which transition is initiated by a wide range of possible background disturbances

This paper investigates the combined effect of radial magnetic field and viscous dissipation on entropy generation in horizontal co-axial cylinders of generalized Couette flow. The analytical solutions for velocity and temperature profiles are obtained and utilized to compute the entropy generation, Bejan number as well as the average entropy generation number. The effect of relevant parameters on