scholarly journals Numerical Simulation of Nozzle Flow Field with Secondary Injection Thrust Vector Control

2018 ◽  
Vol 179 ◽  
pp. 01003
Author(s):  
H.R. Noaman ◽  
Tang Hai Bin ◽  
Elsayed Khalil
Keyword(s):  
Vector Control ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Stagnation Pressure ◽  
Injection Angle ◽  
Thrust Vector Control ◽  
Thrust Vector ◽  
Shock Impingement ◽  
Secondary Injection

Numerical simulations are performed to characterize the secondary injection thrust vector control. For this objective the following measurements were taken: considering the flow to be compressible and turbulent using Realizable k-ε turbulence model accompanied by enhanced wall treatment, the comparison between the CFD results and the experimental results shows a very good agreement. Then a parametric study on injection mass flow rate (changing secondary stagnation pressure) with the same injection location and injection angle is done. The results stated that increasing the injectant mass flow rate lead to shock impingement from opposite wall at secondary stagnation pressure 1.4 of the primary stagnation pressure.

Theoretical Aspects of Thrust Vector Control by Secondary Gas Injection in Rocket Nozzles

1968 ◽  
Vol 72 (686) ◽  
pp. 171-177 ◽  
Author(s):  
John H. Neilson ◽  
Alastair Gilchrist ◽  
Chee K. Lee
Keyword(s):  
Vector Control ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Three Dimensional Flow ◽  
Side Force ◽  
Thrust Vector Control ◽  
Dimensional Flow ◽  
Two Dimensional Flow ◽  
Thrust Vector ◽  
Secondary Injection

This work deals with theoretical aspects of thrust vector control in rocket nozzles by the injection of secondary gas into the supersonic region of the nozzle. The work is concerned mainly with two-dimensional flow, though some aspects of three-dimensional flow in axisymmetric nozzles are considered. The subject matter is divided into three parts. In Part I, the side force produced when a physical wedge is placed into the exit of a two-dimensional nozzle is considered. In Parts 2 and 3, the physical wedge is replaced by a wedge-shaped “dead water” region produced by the separation of the boundary layer upstream of a secondary injection port. The modifications which then have to be made to the theoretical relationships, given in Part 1, are enumerated. Theoretical relationships for side force, thrust augmentation and magnification parameter for two- and three-dimensional flow are given for secondary injection normal to the main nozzle axis. In addition, the advantages to be gained by secondary injection in an upstream direction are clearly illustrated. The theoretical results are compared with experimental work and a comparison is made with the theories of other workers.

scholarly journals Bayesian Mass Averaging in Rigs and Engines

2022 ◽  
pp. 1-15
Author(s):  
Pranay Seshadri ◽  
Andrew Duncan ◽  
George Thorne
Keyword(s):  
Random Field ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Gaussian Random Field ◽  
Analytical Calculation ◽  
Sampling Procedure ◽  
Stagnation Pressure ◽  
Pressure Measurements

Abstract This paper introduces the Bayesian mass average and details its computation. Owing to the complexity of flow in an engine and the limited instrumentation and the precision of the sensor apparatus used, it is difficult to rigorously calculate mass averages. Building upon related work, this paper views any thermodynamic quantity's spatial variation at an axial plane in an engine (or a rig) as a Gaussian random field. In cases where the mass flow rate is constant in the circumferential direction but can be expressed via a polynomial or spline radially, this paper presents an analytical calculation of the Bayesian mass average. In cases where the mass flow rate itself can be expressed as a Gaussian random field, a sampling procedure is presented to calculate the Bayesian mass average. Examples of the calculation of the Bayesian mass average for temperature are presented, including with a real engine case study where velocity profiles are inferred from stagnation pressure measurements.

A Novel Technique for Measuring Stagnation Quantities and Gas Composition in High Temperature Flows

2010 ◽  
Author(s):  
Michela Massini ◽  
Robert J. Miller ◽  
Howard P. Hodson ◽  
Nick Collings
Keyword(s):  
High Temperature ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Gas Turbines ◽  
Stagnation Pressure ◽  
Temperature Measurements ◽  
Stagnation Temperature ◽  
Gas Composition ◽  
Reference Measurements

A new probe has been developed to measure the time averaged stagnation temperature, stagnation pressure and gas composition. This probe can be used in the high temperature regions of gas turbines, including downstream of the combustor and in the first stages of the high pressure turbines, as well as in other environments. The principal benefits of the new probe are that it overcomes the limitations of the standard methods that are used to measure temperature in high temperature environments and that it replaces three separate probes, for the three quantities mentioned above, with one single probe. A novel method of measuring temperature is used, which improves upon the accuracy of thermocouples and increases the temperature operating range. The probe consists of a choked nozzle placed in the hot flow at the point of interest. The working principle is based on the theory that for a choked nozzle, there is a fixed relationship between the stagnation quantities, the gas characteristics and the mass flow rate through the nozzle. The probe has an aspirated phase, where the gas composition and the mass flow rate are measured and a stagnated phase, where the stagnation pressure is measured. The stagnation temperature is determined from the above quantities. The operating principle has been proven valid through laboratory and rig tests. The probe has been successfully tested in a Rolls-Royce Viper engine up to 1000K and 2 bar and in a combustor rig up to 1800K and 4 bars. Measurements of stagnation temperature, stagnation pressure and gas compositions for these tests are presented in the paper and are compared with reference measurements. The accuracy of stagnation pressure and gas composition measurements is equal to the accuracy achievable with techniques that are commonly used in gas turbines. The estimated achievable accuracy of the aspirated probe in terms of temperature measurements is ±0.6%, i.e. ±10K at 1800K, which improves upon the accuracy of temperature measurements performed with standard thermocouples at the same temperatures, the uncertainty of which could be as high as ±2%.

Optimization of the Efficiency of Stall Control Using Air Injection for Centrifugal Compressors—Additional Findings

2018 ◽  
Vol 140 (12) ◽  
Author(s):  
Taher Halawa
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Gas Turbines ◽  
Stable Condition ◽  
Tangential Direction ◽  
Air Injection ◽  
Centrifugal Compressors ◽  
Injection Angle ◽  
Stall Control

This study presents additional important findings to the results of the research paper; “Optimization of the efficiency of stall control using air injection for centrifugal compressors” published in the Journal of Engineering for Gas Turbines and Power in 2015 (Halawa, T., Gadala, M. S., Alqaradawi, M., and Badr, O., 2015, “Optimization of the Efficiency of Stall Control Using Air Injection for Centrifugal Compressors,” ASME J. Eng. Gas Turbines Power, 137(7), p. 072604). The aim of this study is to make a fine determination of the injection angle, which provides the best stable condition when the compressor operates close to stall condition. A relatively narrower range of injection angles with smaller intervals was selected comparing to the results of the referred published paper, which clarified that the best injection angle is 30 deg. External air was injected close to the diffuser entrance at the shroud surface. Injection was applied with mass flow rate equals 1.5% of the design compressor inlet mass flow rate with injection angles ranged from 16 deg to 34 deg measured from the tangential direction at the vaneless region. It was found that both of injection angles of 28 deg and 30 deg achieved the best results in terms of compressor stabilization but each one of them has a specific advantage comparing to the other one. Using injection angle of 28 deg provided the lowest kinetic energy losses while the best orientation of the fluid through diffuser resulted when using an injection angle of 30 deg.

Numerical Investigation of Rotating Stall Characteristics and Active Stall Control in Centrifugal Compressors

2014 ◽  
Author(s):  
Taher Halawa ◽  
Mohamed Alqaradawi ◽  
Osama Badr ◽  
Mohamed S. Gadala
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Rotating Stall ◽  
Air Injection ◽  
Tip Leakage Flow ◽  
Centrifugal Compressors ◽  
Flow Rates ◽  
Injection Angle ◽  
Mass Flow Rates

This paper focuses on providing better view for the understanding of rotating stall phenomenon in centrifugal compressors by using numerical simulations and presents a study of the role of air injection method in delaying stall inception by using different injection parameters aiming at increasing the efficiency of this method. Results showed that the formation of stall begins at the impeller inlet due to early flow separation at low mass flow rates and due to the increase of the turbulence level and the absence of fluid orientation guidance at the vaneless region. The flow weakness causes back flow that results in the formation of the tip leakage flow which causes stall development with time. Results also showed that using air injection at specified locations at the vaneless shroud surface at injection angle of 20° and with injection mass flow rate of 1.5% of the inlet design mass flow rate, can delay the stall onset to happen at lower mass flow rate about 3.8 kg/s comparing with using injection with angle of 10° with different injection mass flow rates and also comparing with the case of no injection.

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