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Journal Article

Using Numerical Simulation to Obtain Length of Constant Area Section in Scramjet Combustor

2020-03-16
Abstract Constant area section length downstream to the fuel injection point is a crucial dimension of scramjet duct geometry. It has a major contribution in creating the maximum effective pressure inside the combustor that is required for propulsion. The length is limited by the thermal choking phenomenon, which occurs when heat is added in a flow through constant area duct. As per theory, to avoid thermal choking the constant area section length depends upon the inlet conditions and the rate of heat addition. The complexity related to mixing and combustion process inside the supersonic stream makes it difficult to predict the rate of heat addition and in turn the length. Recent efforts of simulating the reacting flow inside scramjet combustors are encouraging and can be useful in this regard. The presented work attempts to use simulation results of scramjet combustion for predicting the constant area section length for a typical scramjet combustor.
Journal Article

Analytical Estimation of Infrared Signature of Converging and Converging-Diverging Nozzles of Jet Engine

2021-04-21
Abstract Jet engine hot parts (e.g., jet nozzle) are a crucial source of aircraft’s infrared (IR) signature from the rearview, in 1.9-2.9 μm and 3-5 μm bands. The exhaust nozzle design used in a jet aircraft affects its performance and IR signature (which is also affected just by performance) from the engine layout. For supersonic aircraft (typically for M ∞ > 1.5), a converging-diverging (C-D) nozzle is preferred over a convergent nozzle for optimum performance. The diverging section of the C-D nozzle has a full range of visibility from the rearview; hence, it was not considered a prudent choice for low IR observability. This theoretical study compares the IR signature of the C-D nozzle with that of the convergent nozzle from the rearview in 1.9-2.9 μm and 3-5 μm bands for the same thrust.
Standard

Proper use of Tooling Compensation

2018-01-05
WIP
AIR6972
To inform users on proper use, procedures and common errors when using electronic compensation for tooling on horizontal and vertical balancing machines
Standard

Balance Data Vector Math - Discussion and Usage

2017-10-16
WIP
AIR6964
Provide guidance on how balance machine vector data is captured and reported. Provide an understanding of how to transform balance machine vector data to alternate locations. Provide guidance on how vector imbalances may be used to evaluate and diagnose balance process performance.
Standard

Methods and Criteria for the Balancing of Gas Turbine Rigid Rotors

2015-06-25
WIP
AS6327
This document establishes process parameters for gas turbine rotor balancing. Adherence to the recommendations made herein will facilitate attainment of the usually high degree of accuracy and precision required for jet engine rotor balance.
Standard

Moment Weighing Systems – Single-Axis for Gas Turbine Blade Moment Weight Measurement

2016-11-28
WIP
ARP6914
The scope of these standards will relate to single-axis moment scales only. Topics covered include dimensional characteristics of single-axis moment scale interfaces, general tooling requirements, scale and tooling accuracy, and display instrument accuracy requirements. Additionally, general guidelines for qualification of equipment and tooling are included, as are general requirements for single-axis blade distribution software.
Standard

Recommended Maintenance, Inspection and Monitoring Procedure for Engine Test Cells

2018-12-20
WIP
ARP8540
A guide to maintenance procedures in test cells. A suggested equipment monitoring and/or inspections to reduce the probability of unanticipated failures and associated test cell down time. Guidelines for using typically available data acquisition capabilities in a test cell are provided to utilize normally available trending capability to monitor the testing equipment in addition to using these tools for the usual monitoring of the test article. For the common types of test cells (turboshaft, turboprop, turbojet, and turbofan) test facilities, lists of typical systems with their associated components are provided with suggested inspection intervals and key items to look for in the inspection. A template risk assessment form is provided to facilitate the customization of the assessment of the test cell components to help predict recommended spares.
Standard

Vertical Dynamic Balancing Systems – Isolating Repeatability Issues in Challenging Applications

2021-05-26
WIP
ARP8911
This new Aerospace Recommended Practice will serve as a practical resource that offers guidance to both the machine operator and Process Engineer for isolating the source(s) of non-repeatability in measured unbalance data. The content of this standard addresses: • Vertical Dynamic Machine Capability to achieve the specified unbalance tolerances and repeat within those tolerances • Tooling Capability to repeat within the specified unbalance tolerances • Rotor characteristics that may preclude repeating within the required unbalance tolerances.
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