scholarly journals Detection and Transient Dynamics Modeling of Experimental Hypersonic Inlet Unstart

2012 ◽  
Author(s):  
Kelley Hutchins ◽  
Maruthi Akella ◽  
Noel Clemens ◽  
Jeffrey Donbar
Keyword(s):  
Transient Dynamics ◽  
Dynamics Modeling ◽  
Hypersonic Inlet ◽  
Inlet Unstart

An Experimental Study of Longitudinal Tire Relaxation Constants for Vehicle Traction Dynamics Modeling

2019 ◽  
Author(s):  
Vladimir V. Vantsevich ◽  
Lyubomyr I. Demkiv ◽  
Sviatoslav R. Klos ◽  
Samuel R. Misko ◽  
Lee Moradi
Keyword(s):  
Experimental Study ◽  
Dynamic Models ◽  
Testing Machine ◽  
Transient Dynamics ◽  
Dynamics Modeling ◽  
Test Procedures ◽  
Advantages And Disadvantages ◽  
Frequency Domains ◽  
Tire Testing ◽  
Relaxation Characteristics

Abstract Existing literature on vehicle traction dynamics were reviewed for a variety of vehicle and tire dynamic models, some of which consider the pneumatic tires’ relaxation as a property of vehicle transient dynamics. In general, unlike the lateral relaxation counterpart, the longitudinal tire relaxation characteristics were mostly overlooked in tire transient dynamics modeling. As a continuation of the analytical study published in the 2018 DSCC Proceedings, the co-authors of this paper present an experimental study of the longitudinal tire relaxation characteristics of a Continental MPT 81 tire. Experimental results were obtained by conducting tests on an MTS Flat-Trac LTR tire testing machine. The experimental data is analyzed to investigate longitudinal tire relaxation characteristics as they relate to changes of tire conditions. The goal is to verify and refine the existing models suggested in the literature; as well as, discuss advantages and disadvantages of different test procedures and tire testing equipment. In particular, the paper investigates the longitudinal tire relaxation constant variation due to changes of wheel velocity, tire inflation pressure, and sine oscillations of tire slippage in the time and frequency domains. The paper concludes on the influence of the longitudinal tire relaxation constants on the tire/vehicle traction dynamics modeling.

scholarly journals Volume Dynamics Propulsion System Modeling for Supersonics Vehicle Research

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
George Kopasakis ◽  
Joseph W. Connolly ◽  
Daniel E. Paxson ◽  
Peter Ma
Keyword(s):  
System Dynamics ◽  
System Modeling ◽  
Propulsion System ◽  
System Component ◽  
Ride Quality ◽  
Dynamics Modeling ◽  
Wind Gusts ◽  
Commercial Flight ◽  
Inlet Unstart ◽  
Performance Challenges

Under the NASA Fundamental Aeronautics Program, the Supersonics Project is working to overcome the obstacles to supersonic commercial flight. The proposed vehicles are long, slim body aircrafts with pronounced aeroservoelastic modes. These modes can potentially couple with propulsion system dynamics, leading to performance challenges such as aircraft ride quality and stability. Other disturbances upstream of the engine generated from atmospheric wind gusts, angle of attack, and yaw can have similar effects. In addition, for optimal propulsion system performance, normal inlet-engine operations are required to be closer to compressor stall and inlet unstart. To study these phenomena, an integrated model is needed that includes both airframe structural dynamics and the propulsion system dynamics. This paper covers the propulsion system component volume dynamics modeling of a turbojet engine that will be used for an integrated vehicle aeropropulsoservoelastic model and for propulsion efficiency studies.

A CFD assessment of classifications for hypersonic inlet start/unstart phenomena

2009 ◽  
Vol 113 (1142) ◽  
pp. 263-271 ◽  
Author(s):  
J. Chang ◽  
D. Yu ◽  
W. Bao ◽  
Z. Xie ◽  
Y. Fan
Keyword(s):  
Support Vector Machine ◽  
Classification Accuracy ◽  
Support Vector ◽  
Flight Tests ◽  
Multiple Classifiers ◽  
Hypersonic Inlet ◽  
Multiple Classifiers Fusion ◽  
Inlet Unstart ◽  
The Membership Function ◽  
Hypersonic Inlets

Abstract Inlet start/unstart detection is one of the most important issues of hypersonic inlets and is also the foundation of protection controls of scramjets. In ground and flight tests, it is inevitably to introduce the sensor noises to the measurement system. How to overcome or weaken the influence of the sensor noises and the outer disturbances is an important issue to the control system of the engine. To solve this problem, the 2D inner steady flow of hypersonic inlets was numerically simulated in different freestream conditions and backpressures, and two different inlet unstart phenomena were analysed. The membership function for hypersonic inlet start/unstart can be obtained by using probabilistic output support vector machine, and the algorithm of multiple classifiers fusion is introduced. The variations of the classification accuracy with the intensity of the sensor noises and the number of the classifier were discussed respectively. In conclusion, it is useful to introduce the algorithm of support vector machine and multiple classifiers fusion to overcome or weaken the influence of the sensor noises on the classification accuracy of hypersonic inlet start/unstart. The number of the practical fusion classifiers needs a tradeoff between the fusion classification accuracy and the complexity of the classification system.

scholarly journals Unstart Coupling Mechanism Analysis of Multiple-Modules Hypersonic Inlet

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Jichao Hu ◽  
Juntao Chang ◽  
Lei Wang ◽  
Shibin Cao ◽  
Wen Bao
Keyword(s):  
Oscillatory Flow ◽  
Coupling Effect ◽  
The Other ◽  
Coupling Mechanism ◽  
Mechanism Analysis ◽  
Reversed Flow ◽  
Hypersonic Inlet ◽  
Scramjet Engine ◽  
Coupling Characteristic ◽  
Inlet Unstart

The combination of multiplemodules in parallel manner is an important way to achieve the much higher thrust of scramjet engine. For the multiple-modules scramjet engine, when inlet unstarted oscillatory flow appears in a single-module engine due to high backpressure, how to interact with each module by massflow spillage, and whether inlet unstart occurs in other modules are important issues. The unstarted flowfield and coupling characteristic for a three-module hypersonic inlet caused by center module II and side module III were, conducted respectively. The results indicate that the other two hypersonic inlets are forced into unstarted flow when unstarted phenomenon appears on a single-module hypersonic inlet due to high backpressure, and the reversed flow in the isolator dominates the formation, expansion, shrinkage, and disappearance of the vortexes, and thus, it is the major factor of unstart coupling of multiple-modules hypersonic inlet. The coupling effect among multiple modules makes hypersonic inlet be more likely unstarted.

scholarly journals Volume Dynamics Propulsion System Modeling for Supersonics Vehicle Research

2008 ◽  
Author(s):  
George Kopasakis ◽  
Joseph W. Connolly ◽  
Daniel E. Paxson ◽  
Peter Ma
Keyword(s):  
System Dynamics ◽  
System Modeling ◽  
Propulsion System ◽  
System Component ◽  
Ride Quality ◽  
Elastic Model ◽  
Dynamics Modeling ◽  
Elastic Modes ◽  
Inlet Unstart ◽  
Performance Challenges

Under the NASA Fundamental Aeronautics Program the Supersonics Project is working to overcome the obstacles to supersonic commercial flight. The proposed vehicles are long slim body aircraft with pronounced aero-servo-elastic modes. These modes can potentially couple with propulsion system dynamics; leading to performance challenges such as aircraft ride quality and stability. Other disturbances upstream of the engine generated from atmospheric wind gusts, angle of attack, and yaw can have similar effects. In addition, for optimal propulsion system performance, normal inlet-engine operations are required to be closer to compressor stall and inlet unstart. To study these phenomena an integrated model is needed that includes both airframe structural dynamics as well as the propulsion system dynamics. This paper covers the propulsion system component volume dynamics modeling of a turbojet engine that will be used for an integrated vehicle Aero-Propulso-Servo-Elastic model and for propulsion efficiency studies.

Dimensionless analysis of the unstart boundary for 2D mixed hypersonic inlets

2008 ◽  
Vol 112 (1135) ◽  
pp. 547-555 ◽  
Author(s):  
J. Chang ◽  
D. Yu ◽  
W. Bao ◽  
L. Qu
Keyword(s):  
Experimental Data ◽  
Pressure Ratio ◽  
Major Effect ◽  
Navier Stokes ◽  
Analysis Method ◽  
External Compression ◽  
Dimensionless Analysis ◽  
Hypersonic Inlet ◽  
Dimensional Analysis Method ◽  
Inlet Unstart

Abstract Inlet unstart boundary is one of the most important issues of the hypersonic inlet and is also the foundation of the protection control of a scramjet. To solve this problem, the 2D internal steady flow of a 2D mixed internal/external compression hypersonic inlet was numerically simulated at different freestream conditions and backpressures with a RANS (Reynolds-Averaged Navier-Stokes) solver using a RNG (Renormalisation Group) k-ε turbulence model, and two different inlet unstart phenomena were analysed. The dimensional analysis method was introduced to find the essence variables describing the inlet unstart boundary based on “numerical experimental” data in this paper. The dimensionless pressure ratios of the forebody and isolator were analysed respectively. The results show that the unstart boundary of the 2D mixed hypersonic inlet is determined by M0, α and Re0. Pressure ratio π increases with M0 increasing, and it increases firstly and decreases then with α increasing. Pressure ratio π increases with Re0 increasing. Re0 (Re0 < 2 × 107) has a major effect on π and Re0 (Re0 > 2×107) has little effect on π.

Experimental Identification of Transient Dynamics for Supersonic Inlet Unstart

2014 ◽  
Vol 30 (6) ◽  
pp. 1605-1612 ◽  
Author(s):  
Kelley E. Hutchins ◽  
Maruthi R. Akella ◽  
Noel T. Clemens ◽  
Jeffrey M. Donbar ◽  
Sivaram Gogineni
Keyword(s):  
Transient Dynamics ◽  
Experimental Identification ◽  
Supersonic Inlet ◽  
Inlet Unstart
Sign in / Sign up

Export Citation Format

Share Document