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Test Cell Analytical Thrust Correction

EG-1E Gas Turbine Test Facilities and Equipment
  • Aerospace Standard
  • AIR5436A
  • Current
Published 2019-07-02 by SAE International in United States
This document describes a method to correct engine thrust, measured in an indoor test cell, for the aerodynamic effects caused by the secondary airflow induced in the test cell by the engine operating in an enclosed environment in close proximity to an exhaust duct. While it is not recommended to be used to replace test cell correlation, it does provide a means to verify an existing thrust correlation factor.
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Material Properties of Granular Ice Layers Characterized Using a Rigid-Body-Penetration Method: Experiments and Modeling

Technical University of Darmstadt-Markus Schremb, Kenan Malicevic, Louis Reitter, Ilia Roisman, Cameron Tropea
Published 2019-06-10 by SAE International in United States
Accretion and shedding of ice layers is a serious problem for various engineering applications. In particular, ice layers growing due to ice crystal impingement on warm parts of an aircraft jet engine pose a severe hazard since they seriously affect safe operation of an aircraft. The material properties, and in the first place the strength of an ice layer, are crucial for the mechanisms leading to, and taking place during, both accretion and shedding of an ice layer. In the present study, the apparent yield strength of dry granular ice layers is examined employing a novel rigid-body-penetration approach. Dynamic projectile penetration into granular ice layers of varying porosity and ice grain size is experimentally investigated for different projectile impact velocities using a high-speed video system and post-processing of the captured video data. The obtained data for the total penetration depth of the projectile is used to calculate the apparent yield strength of the ice layer based on theoretical modeling of the projectile dynamics during penetration. Finally, the experimental method and theoretical modeling employed in the…
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Ice-Crystal Icing Accretion Studies at the NASA Propulsion Systems Laboratory

NASA John Glenn Research Center-Peter M. Struk, Juan Agui, Thomas Ratvasky, Michael King
Ohio Aerospace Institute-Tadas Bartkus, Jen-Ching Tsao
Published 2019-06-10 by SAE International in United States
This paper describes an ice-crystal icing experiment conducted at the NASA Propulsion System Laboratory during June 2018. This test produced ice shape data on an airfoil for different test conditions similar to those inside the compressor region of a turbo-fan jet engine. Mixed-phase icing conditions were generated by partially freezing out a water spray using the relative humidity of flow as the primary parameter to control freeze-out. The paper presents the ice shape data and associated conditions which include pressure, velocity, temperature, humidity, total water content, melt ratio, and particle size distribution. The test featured a new instrument traversing system which allowed surveys of the flow and cloud. The purpose of this work was to provide experimental ice shape data and associated conditions to help develop and validate ice-crystal icing accretion models. The results support previous experimental observations of a minimum melt-ratio threshold for accretion to occur as well as the existence of a plateau region where the icing severity is high for a range of melt ratios. However, a maximum limit for melt ratio,…
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A Continuing Investigation of Diurnal and Location Trends in an Ice Crystal Icing Engine Event Database

Boeing Co-Melissa Bravin
Met Analytics, Inc.-J. Walter Strapp
Published 2019-06-10 by SAE International in United States
Due to ongoing efforts by the aviation industry, much has been learned over the last several years regarding jet engine power loss and compressor damage events caused by the ingestion of high concentrations of ice crystal particles into the core flow path. Boeing has created and maintained a database of such ice crystal icing (ICI) events to aid in analysis and further study of this phenomenon. This article provides a general update on statistics derived from the Boeing event database, and provides more details on specific event clusters of interest. A series of three flight campaigns have, over the past five years, collected in-situ data in deep convective clouds that will be used for the assessment of the new FAA CFR Part 33 ice crystal environmental envelope Appendix D, and the equivalent EASA CS-25 Appendix P. The most recent Boeing engine event study in 2015 focused on oceanic cloud systems that caused events in Southeast Asia, a region expected to have similar cloud properties as the first flight campaign in Darwin, Australia. The current study…
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Numerical Investigation of the NASA Glenn Propulsion Systems Laboratory

U.S. Air Force Academy-Ioan Feier
Published 2019-06-10 by SAE International in United States
NASA Glenn Research Center’s Propulsion Systems Laboratory (PSL) allows ice-crystal ice accretion tests on jet engines. This pressurized wind tunnel facility allows engines to be operated at flight altitudes and temperatures. Steady state and unsteady computational fluid dynamics simulations were performed for the PSL geometry, including the spray bars with their supports, and the converging duct section. These simulation results help to characterize the performance of the tunnel and are important for understanding the flow and particle behavior leading up to the engine test section. The results indicate complex flow structures, with vortex shedding and non-uniform flow features. Flow separation is observed in several regions. Several flow features and vortices are seen to persist to the duct exit plane where the fan section of a jet engine would be mounted for testing. Unsteady simulations show that periodic vortex shedding is created by the spray bars, and that the generated crosswise vorticity is converted to streamwise and antistreamwise vorticity through the acceleration and stretching of the flow structures in the converging duct section. Flow nonuniformity is…
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Enhanced Ultrasonic Immersion Inspection for Titanium Alloy and other Metal Alloy Billets

AMS K Non Destructive Methods and Processes Committee
  • Aerospace Material Specification
  • AMS2628B
  • Current
Published 2019-05-16 by SAE International in United States
This specification covers procedures for ultrasonic immersion inspection of premium grade wrought titanium and titanium alloy round billet 5 inches (127 mm) and over in nominal diameter (see 8.5). Metal alloy billets other than titanium may be tested to this specification with the use of suitable reference standards.
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Using a System Reliability Model to Optimize Maintenance Costs A Best Practices Guide

HM-1 Integrated Vehicle Health Management Committee
  • Aerospace Standard
  • JA6097_201905
  • Current
Published 2019-05-07 by SAE International in United States
SAE JA6097 (“Using a System Reliability Model to Optimize Maintenance”) shows how to determine which maintenance to perform on a system when that system requires corrective maintenance to achieve the lowest long-term operating cost. While this document may focus on applications to Jet Engines and Aircraft, this methodology could be applied to nearly any type of system. However, it would be most effective for systems that are tightly integrated, where a failure in any part of the system causes the entire system to go off-line, and the process of accessing a failed component can require additional maintenance on other unrelated components.
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Balancing Machines, Dynamic, Ball Type Slave Bearings for Rotor Support

EG-1A Balancing Committee
  • Aerospace Standard
  • ARP1202B
  • Current
Published 2019-04-25 by SAE International in United States
This ARP specifies both the nominal dimensions and the tolerances for a series of ball bearings with semifinished inside diameters which are suitable for supporting gas turbine rotating components in dynamic balancing machines.
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Fatigue Damage Modeling Approach Based on Evolutionary Power Spectrum Density

Concordia University-Ayhan Ince, Jean-Gabriel Lacombe
Purdue University-Zhui Li
Published 2019-04-02 by SAE International in United States
Fatigue damage prediction approaches in both time and frequency domains have been developed to simulate the operational life of mechanical structures under random loads. Fatigue assessment of mechanical structures and components subjected to those random loads is increasingly being addressed by frequency domain approaches because of time and cost savings. Current frequency-based fatigue prediction methods focus on stationary random loadings (stationary Power Spectral Density), but many machine components, such as jet engines, rotating machines, and tracked vehicles are subjected to non-stationary PSD conditions under real service loadings. This paper describes a new fatigue damage modeling approach capable of predicting fatigue damage for structures exposed to non-stationary (evolutionary) PSD loading conditions where the PSD frequency content is time-varying. The underlying concept of the proposed approach is that the evolutionary response PSD function of a structure can be decomposed into a finite number of narrow frequency bands which can be associated with Rayleigh distributions. Fatigue damage is estimated by summing up damages for each individual band on the basis of an appropriate damage accumulation rule. The proposed…
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Using Ruggedized Test Equipment to Solve Jet Engine Problems

  • Magazine Article
  • TBMG-34128
Published 2019-04-01 by Tech Briefs Media Group in United States

A jet engine is the very definition of “mission-critical.” A critical failure could cause a serious accident that endangers hundreds of lives. To prevent this from happening, manufacturers perform extensive testing on jet engine components, systems, and manufacturing processes.