Effects of Chevron nozzles on engine performance and jet noise of a turbojet engine and test environment

This paper presents a study regarding the noise reduction of the turbojet engine, in particular the jet noise of a micro turbojet engine. The results of the measurement campaign are presented followed by a performances analysis which is based on the measured data by the test bench. Within the tests, beside the baseline nozzle other two nozzles with chevrons were tested and evaluated. First type of nozzle is foreseen with eight triangular chevrons, the length of the chevrons being L = 10 percentages from the equivalent diameter and an immersion angle of I = 0 deg. For the second nozzle the length and the immersion angle were maintained, only the chevrons number were increased at 16. The micro turbojet engine has been tested at four different regimes of speed. The engine performances were monitored by measuring the fuel flow, the temperature in front of the turbine, the intake air flow, the compression ratio, the propulsion force and the temperature before the compressor. In addition, during the testing, the vibrations were measured on axial and radial direction which indicate a normal functioning of the engine during the chevron nozzles testing. Regarding the noise, it was concluded that at low regimes the noise doesn’t presents any reduction when using the chevron nozzles, while at high regimes an overall noise reduction of 2–3 dB(A) was achieved. Regarding the engine performances, a decrease in the temperature in front of the turbine, compression ratio and the intake air and fuel flow was achieved and also a drop of few percent of the propulsion force.

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Stady on the Effect of Chevron Nozzles on Turbo Jet Engine performance and Jet Noise

The Proceedings of the Thermal Engineering Conference ◽

10.1299/jsmeted.2016.e123 ◽

2016 ◽

Vol 2016 (0) ◽

pp. E123

Author(s):

Makoto Miyake ◽

Gakuyo Tamada ◽

Toshiaki Tsuchiya

Keyword(s):

Engine Performance ◽

Jet Noise ◽

Jet Engine ◽

Chevron Nozzles

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A Flight Simulation Vision for Aeropropulsion Altitude Ground Test Facilities

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.1806452 ◽

2005 ◽

Vol 127 (1) ◽

pp. 8-17 ◽

Cited By ~ 3

Author(s):

Milt Davis ◽

Peter Montgomery

Keyword(s):

System Performance ◽

Engine Performance ◽

Aircraft Engine ◽

Flight Simulation ◽

Propulsion System ◽

Test Facility ◽

Flight Testing ◽

Test Environment ◽

Ground Test ◽

Aircraft System

Testing of a gas turbine engine for aircraft propulsion applications may be conducted in the actual aircraft or in a ground-test environment. Ground test facilities simulate flight conditions by providing airflow at pressures and temperatures experienced during flight. Flight-testing of the full aircraft system provides the best means of obtaining the exact environment that the propulsion system must operate in but must deal with limitations in the amount and type of instrumentation that can be put on-board the aircraft. Due to this limitation, engine performance may not be fully characterized. On the other hand, ground-test simulation provides the ability to enhance the instrumentation set such that engine performance can be fully quantified. However, the current ground-test methodology only simulates the flight environment thus placing limitations on obtaining system performance in the real environment. Generally, a combination of ground and flight tests is necessary to quantify the propulsion system performance over the entire envelop of aircraft operation. To alleviate some of the dependence on flight-testing to obtain engine performance during maneuvers or transients that are not currently done during ground testing, a planned enhancement to ground-test facilities was investigated and reported in this paper that will allow certain categories of flight maneuvers to be conducted. Ground-test facility performance is simulated via a numerical model that duplicates the current facility capabilities and with proper modifications represents planned improvements that allow certain aircraft maneuvers. The vision presented in this paper includes using an aircraft simulator that uses pilot inputs to maneuver the aircraft engine. The aircraft simulator then drives the facility to provide the correct engine environmental conditions represented by the flight maneuver.

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Energetic, exergetic, exergoeconomic, environmental (4E) and sustainability performances of an unmanned aerial vehicle micro turbojet engine

Aircraft Engineering and Aerospace Technology ◽

10.1108/aeat-03-2021-0088 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Ozgur Balli ◽

Alper Dalkıran ◽

Tahir Hikmet Karakoç

Keyword(s):

Environmental Sustainability ◽

Engine Performance ◽

Maximum Energy ◽

Content Type ◽

Cost Rate ◽

Turbojet Engine ◽

Energy And Exergy ◽

Aerial Vehicle ◽

Exergoeconomic Analysis ◽

Engine Systems

Purpose This study aims to investigate the aviation, energetic, exergetic, environmental, sustainability and exergoeconomic performances of a micro turbojet engine used in unmanned aerial vehicles at four different modes. Design/methodology/approach The engine data were collected from engine test cell. The engine performance calculations were performed for four different operation modes. Findings According to the results, maximum energy and exergy efficiency were acquired as 19.19% and 18.079% at Mode 4. Total cost rate was calculated as 6.757 $/h at Mode-1, which varied to 10.131 $/h at Mode-4. Exergy cost of engine power was observed as 0.249 $/MJ at Mode-1, which decreased to 0.088 $/MJ at Mode-4 after a careful exergoeconomic analysis. Originality/value The novelty of this work is the capability to serve as a guide for similar systems with a detailed approach in the thermodynamic, thermoeconomic and environmental assessments by prioritizing efficiency, fuel consumption and cost formation. This investigation intends to establish a design of the opportunities and benefits that the thermodynamic approach provides to turbojet engine systems.

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Investigation on the Influence of a Core Chevron Nozzle on the Performance of a Modern Bypass Engine

Volume 5: Turbo Expo 2004, Parts A and B ◽

10.1115/gt2004-53212 ◽

2004 ◽

Cited By ~ 2

Author(s):

Matthias Weißschuh ◽

Stephan Staudacher

Keyword(s):

Engine Performance ◽

Ambient Air ◽

Performance Comparison ◽

Turbine Engines ◽

Gas Streams ◽

Discharge Velocity ◽

Chevron Nozzle ◽

Nozzle Configuration ◽

Chevron Nozzles ◽

Considerable Work

In light of intensifying environmental concerns, the noise in aircraft gas turbine engines needs to be reduced significantly. Considerable work has been conducted to reduce jet noise produced by the mixing of high velocity gas streams with ambient air. Various nozzle designs such as lobed nozzles, serrated nozzles or chevron nozzles have been used and proposed to control and modify the velocity pattern of exhaust gas streams. This paper presents investigations on the influence of a core chevron nozzle on the performance of a modern bypass engine. The characteristic discharge, velocity and specific thrust coefficients of the chevron and non-chevron nozzles are determined by numerical calculations and are verified with experimental data. The nozzle coefficients form the basis for an engine performance comparison between the two hot nozzle configurations of the bypass engine. The effect of the nozzle configuration on overall engine performance and component working points has been investigated by applying an engine performance synthesis tool. The thrust loss and the corresponding SFC increase which has been observed by using the chevron nozzle have been related to engine internal rematching and changes in nozzle performance.

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