scholarly journals Optimization Aspects of an Ejector Type Hypersonic Thrust Nozzle

1992 ◽  
Author(s):  
G. Trittler ◽  
E. Eckert ◽  
M. Göing
Keyword(s):  
High Performance ◽  
Exhaust System ◽  
Vital Role ◽  
Calculation Model ◽  
Nozzle Geometry ◽  
Design Parameters ◽  
Axial Thrust ◽  
Thrust Coefficient ◽  
Wide Range ◽  
Low Performance

Hypersonic aircraft projects are highly dependant on efficient propulsion systems. High performance and integration within the airframe play a vital role in the overall concept. Particular attention must be paid to the exhaust system that is submitted to a wide range of operational requirements. An optimization of the nozzle geometry for high flight Mach numbers will lead to a low performance at the transonic flight regime. The additional use of secondary ejector air flow at transonic speeds is one option to improve the thrust behaviour of the nozzle. In the presented paper performance data of single expansion ramp ejector type nozzles are predicted using a calculation model based on a method-of-characteristics algorithm. For optimization purposes the effects of various design parameters on axial thrust coefficient and thrust vector angle are discussed. The geometric parameters investigated are the length of the lower nozzle wall and its deflection angle as well as the ejector slot location and its cross-section.

A Family of Surface Velocity Distributions for Axial Compressor Blading and Their Theoretical Performance

1976 ◽  
Vol 98 (2) ◽  
pp. 229-238 ◽  
Author(s):  
G. J. Walker
Keyword(s):  
High Performance ◽  
Axial Compressor ◽  
Compressor Blade ◽  
Surface Velocity ◽  
Design Parameters ◽  
Suction Surface ◽  
Wide Range ◽  
Using Data ◽  
High Level ◽  
Theoretical Performance

The influence of free stream disturbances on transition is discussed and it is noted that significant regions of laminar flow may exist on axial turbomachine blades despite the high level of disturbance to which they are subjected. A family of surface velocity distributions giving unseparated flow on the suction surface of an axial compressor blade is derived using data from detailed boundary layer measurements on the blading of a single-stage machine. The distributions are broadly similar to those adopted by Wortmann in designing high performance isolated aerofoil sections for operation at much higher Reynolds numbers. The theoretical performance of blades having the specified surface velocity distributions is computed for a wide range of conditions, and the effects of varying Reynolds number and other design parameters are analyzed. The results suggest the possibility of obtaining useful improvements in performance over that of conventional compressor blade sections. The computed performance values show an almost unique relation between the blade losses and the suction surface diffusion ratio. However the correlation of losses with the equivalent diffusion ratio is found to break down at high values of the latter parameter.

Investigation on the Degree of Reaction in Twin Scroll Radial Turbines at Different Operating Conditions for Turbocharging Applications

2019 ◽  
Author(s):  
Carlo Cravero ◽  
Davide De Domenico ◽  
Andrea Ottonello
Keyword(s):  
High Performance ◽  
Mean Value ◽  
Operating Conditions ◽  
Axial Thrust ◽  
Degree Of Reaction ◽  
Radial Turbine ◽  
Wide Range ◽  
Partial Admission ◽  
Rotor Losses ◽  
Radial Turbines

Abstract Frequently in turbocharging radial turbine studies, some assumptions have to be done in order to make 1D matching calculations as easy as possible and to develop simulation approaches that can be useful for different purposes, like axial thrust prediction. One of these assumptions concerns the degree of reaction, which is often considered constant and equal to the value 0.5. In standard radial turbines design the velocity triangles are set by the target to keep a mean degree of reaction of 50%, in order to obtain low rotor losses and to minimize the exit swirl to get lower losses in the exhaust diffuser. From the experience gained on radial turbines operating in a wide range of conditions, it is evident that: the degree of reaction presents large variations along a given isospeed (especially at low rotational speed) and the mean value is far from 0.5 (particularly true in high performance applications). In the present work a method for the representation of the degree of reaction for radial turbine is suggested. The approach has been developed onto a twin scroll radial turbine for turbocharging, considering a large dataset of operating conditions (at both equal and partial admission). The discussion and the method suggested are based on a rich database from experimental data and numerical simulations developed by the authors on the 3D configuration of the turbines under investigation.

Comparison of the Propulsion Performance of Aerospike and Bell-Shaped Nozzle Using Hydrogen Peroxide Monopropellant Under Sea-Level Condition

2018 ◽  
Vol 35 (3) ◽  
pp. 427-440
Author(s):  
A. Lai ◽  
S. S. Wei ◽  
C. H. Lai ◽  
J. L. Chen ◽  
Y. H. Liao ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
High Performance ◽  
Ambient Pressure ◽  
Pressure Ratio ◽  
Species Conservation ◽  
Thrust Coefficient ◽  
Propulsion Performance ◽  
Wide Range ◽  
Aerospike Nozzle ◽  
Volume Method

ABSTRACTThis study investigates numerically the performance of applying aerospike nozzle in a hydrogen peroxide mono-propellant propulsion system. A set of governing equations, including continuity, momentum, energy and species conservation equations with extended k-ε turbulence equations, are solved using the finite-volume method. The hydrogen peroxide mono-propellant is assumed to be fully decomposed into water vapor and oxygen after flowing through a catalyst bed before entering the nozzle. The aerospike nozzle is expected to have high performance even in deep throttling cases due to its self-compensating characteristics in a wide range of ambient pressure environments. The results show that the thrust coefficient efficiency (Cf,η) of this work exceeds 90% of the theoretical value with a nozzle pressure ratio (PR) in the range of 20 ~ 45. Many complex gas dynamics phenomena in the aerospike nozzle are found and explained in the paper. In addition, performance of the aerospike nozzle is compared with that of the bell-shape nozzle.

Numerical Investigation on a New Concept of Shock Vector Control Nozzle

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Shi Jingwei ◽  
Wang Zhanxue ◽  
Zhou Li ◽  
Zhang Xiaobo
Keyword(s):  
Vector Control ◽  
Secondary Flow ◽  
Pressure Ratio ◽  
Exhaust System ◽  
Operating Conditions ◽  
Thrust Coefficient ◽  
Wide Range ◽  
Aero Engine ◽  
Coupling Performance ◽  
Vector Efficiency

Shock vector control (SVC) based on transverse jet injection is one of the fluidic thrust vectoring (FTV) technologies, and is considered as a promising candidate for the future exhaust system working at high nozzle pressure ratio (NPR). However, the low vector efficiency (η) of the SVC nozzle remains an important problem. In the paper, a new method, named as the improved SVC, was proposed to improve the vector efficiency (η) of a SVC nozzle, which enhances the vector control of primary supersonic flow by adopting a bypass injection. It needs less secondary flow from high pressure component of an aero-engine and has smaller influence on the working character of an aero-engine. The flow mechanism of the improved SVC nozzle was investigated by solving three-dimensional Reynolds-averaged Navier--Stokes with shear stress transport (SST) κ–ω turbulence model. The shock waves, jets-primary flow interactions, flow separation, and vector performance were analyzed. The influences of aerodynamic and geometric parameters, namely, NPR, secondary pressure ratio (SPR), and bypass injection position (Xj.ad.) on flow characteristics and vector performance were investigated. Based on the design of experiment (DOE), the response surface methodology (RSM) and the simulation model of an aero-engine, a method to estimate the coupling performance of the improved SVC nozzle and an aero-engine was studied, and a new balance relationship between the improved SVC nozzle and an aero-engine was established. Results shows that (1) with the assistance of bypass injection, the jet penetration and the capability of vector control are largely improved, resulting in a vector efficiency (η) of 1.98 deg/%-ω at the designed NPRD = 13.88; (2) in a wide range of operating conditions, larger vector angle (δp), higher thrust coefficient (Cfg), and higher vector efficiency (η) of the improved SVC nozzle were obtained, (3) in the coupling process of the improved SVC nozzle and an aero-engine, a δp of 18.1 deg was achieved at corrected secondary flow ratio of 10% and corrected bypass ratio of 6.98%, and the change of the thrust and the specific fuel consumption (SFC) were within 12%, which is better than the coupling performance of a SVC nozzle and an aero-engine.

Dynamic Structural Properties of Compliant Foil Thrust Bearings—Comparison Between Experimental and Theoretical Results

1994 ◽  
Vol 116 (1) ◽  
pp. 70-75 ◽  
Author(s):  
C.-P. Roger Ku
Keyword(s):  
Dynamic Characteristics ◽  
High Performance ◽  
Operating Conditions ◽  
Design Parameters ◽  
Static Loads ◽  
Thrust Bearings ◽  
Equivalent Damping ◽  
Foil Bearings ◽  
Compliant Surface ◽  
Wide Range

This paper describes an experimental investigation into the dynamic characteristics of corrugated foil (bump foil) strips used in compliant surface foil thrust bearings. This study provided the first opportunity to quantify the dynamic structural stiffness and equivalent damping coefficients of bump foil strips for a wide range of operating conditions. The experimental data were compared to results obtained by a theoretical model developed earlier. The effects of bearing design parameters, such as static loads, dynamic displacement amplitudes, bump configurations, pivot locations, surface coatings, and lubricant were also evaluated. An understanding of the dynamic characteristics of bump foil strips resulting from this work offers designers a means for enhancing the design of high-performance compliant foil bearings.

An Experimental and Theoretical Study of Dynamic Structural Stiffness in Compliant Foil Bearings

1993 ◽  
Author(s):  
C.-P. Roger Ku
Keyword(s):  
Dynamic Characteristics ◽  
High Performance ◽  
Operating Conditions ◽  
Design Parameters ◽  
Structural Stiffness ◽  
Static Loads ◽  
Foil Bearings ◽  
Compliant Surface ◽  
Wide Range ◽  
Bearing Design

Abstract This paper describes an experimental investigation into the dynamic characteristics of corrugated foil (bump foil) strips used in compliant surface foil bearings. This study provided the first opportunity to quantify the dynamic structural stiffness of bump foil strips for a wide range of operating conditions. The experimental data were compared to results obtained by a theoretical model developed earlier, and the comparisons show very good agreement. The effects of bearing design parameters, such as static loads, dynamic displacement amplitudes, bump configurations, pivot locations, surface coatings, and lubricant were also evaluated. An understanding of the dynamic characteristics of bump foil strips resulting from this work offers designers a means for enhancing the design of high-performance compliant foil bearings.

INCOLOY ALLOY 864

Alloy Digest ◽  
1998 ◽  
Vol 47 (2) ◽  
Keyword(s):  
Corrosion Resistance ◽  
High Temperature ◽  
Mechanical Strength ◽  
High Performance ◽  
Exhaust System ◽  
Good Combination ◽  
Fatigue Properties ◽  
Temperature Performance ◽  
Incoloy Alloy ◽  
Oxidation And Corrosion

Abstract Incoloy Alloy 864 is a high performance alloy developed specifically for automotive exhaust system flexible couplings and other exhaust applications. The alloy has a good combination of oxidation and corrosion resistance, with good mechanical strength, stability, and fatigue properties. This datasheet provides information on composition, physical properties, and elasticity. It also includes information on high temperature performance and corrosion resistance as well as joining. Filing Code: SS-708. Producer or source: Inco Alloys International Inc.

Validated Stability Indicating HPTLC Method for the Estimation of Amoxapine in Different Stress Conditions

2019 ◽  
Vol 15 (3) ◽  
pp. 273-279
Author(s):  
Shweta G. Rangari ◽  
Nishikant A. Raut ◽  
Pradip W. Dhore
Keyword(s):  
High Performance ◽  
Limit Of Detection ◽  
Degradation Products ◽  
Analysis Data ◽  
Peak Height ◽  
Good Resolution ◽  
Stability Indicating ◽  
Limit Of Quantitation ◽  
Wide Range ◽  
Hptlc Method

Background:The unstable and/or toxic degradation products may form due to degradation of drug which results into loss of therapeutic activity and lead to life threatening condition. Hence, it is important to establish the stability characteristics of drug in various conditions such as in temperature, light, oxidising agent and susceptibility across a wide range of pH values.Introduction:The aim of the proposed study was to develop simple, sensitive and economic stability indicating high performance thin layer chromatography (HPTLC) method for the quantification of Amoxapine in the presence of degradation products.Methods:Amoxapine and its degraded products were separated on precoated silica gel 60F254 TLC plates by using mobile phase comprising of methanol: toluene: ammonium acetate (6:3:1, v/v/v). The densitometric evaluation was carried out at 320 nm in reflectance/absorbance mode. The degradation products obtained as per ICH guidelines under acidic, basic and oxidative conditions have different Rf values 0.12, 0.26 and 0.6 indicating good resolution from each other and pure drug with Rf: 0.47. Amoxapine was found to be stable under neutral, thermal and photo conditions.Results:The method was validated as per ICH Q2 (R1) guidelines in terms of accuracy, precision, ruggedness, robustness and linearity. A good linear relationship between concentration and response (peak area and peak height) over the range of 80 ng/spot to 720 ng/spot was observed from regression analysis data showing correlation coefficient 0.991 and 0.994 for area and height, respectively. The limit of detection (LOD) and limit of quantitation (LOQ) for area were found to be 1.176 ng/mL and 3.565 ng/mL, whereas for height, 50.063 ng/mL and 151.707 ng/mL respectively.Conclusion:The statistical analysis confirmed the accuracy, precision and selectivity of the proposed method which can be effectively used for the analysis of amoxapine in the presence of degradation products.

Phytochemical, Analytical and Medicinal Studies of Holoptelea integrifolia Roxb. Planch - A Review

2019 ◽  
Vol 5 (4) ◽  
pp. 270-277 ◽  
Author(s):  
Vijay Kumar ◽  
Simranjeet Singh ◽  
Ragini Bhadouria ◽  
Ravindra Singh ◽  
Om Prakash
Keyword(s):  
Liquid Chromatography ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
High Performance ◽  
Biologically Active ◽  
Toxicological Studies ◽  
Wide Range ◽  
Layer Chromatography

Holoptelea integrifolia Roxb. Planch (HI) has been used to treat various ailments including obesity, osteoarthritis, arthritis, inflammation, anemia, diabetes etc. To review the major phytochemicals and medicinal properties of HI, exhaustive bibliographic research was designed by means of various scientific search engines and databases. Only 12 phytochemicals have been reported including biologically active compounds like betulin, betulinic acid, epifriedlin, octacosanol, Friedlin, Holoptelin-A and Holoptelin-B. Analytical methods including the Thin Layer Chromatography (TLC), High-Performance Thin Layer Chromatography (HPTLC), High-Performance Liquid Chromatography (HPLC) and Liquid Chromatography With Mass Spectral (LC-MS) analysis have been used to analyze the HI. From medicinal potency point of view, these phytochemicals have a wide range of pharmacological activities such as antioxidant, antibacterial, anti-inflammatory, and anti-tumor. In the current review, it has been noticed that the mechanism of action of HI with biomolecules has not been fully explored. Pharmacology and toxicological studies are very few. This seems a huge literature gap to be fulfilled through the detailed in-vivo and in-vitro studies.

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