Vital Role of Shock-cell and Mach disk in Noise Production of Jet Engines

Inhaltsverzeichnis (Table of Contents)

• Introduction
• Literature Review
• Jet Noise
• Shock-cell Noise
• Mach Disk Noise
• Experimental Setup
• Shadowgraph Technique
• Nozzle Design
• Instrumentation
• Data Analysis
• Image Processing
• Shock-cell Spacing Measurement
• Theoretical Shock-cell Length Calculation
• Results and Discussion
• Shock-cell Structure Visualization
• Effect of Temperature Ratio (TR)
• Effect of Nozzle Pressure Ratio (NPR)
• Effect of Nozzle Geometry
• Conclusion

Zielsetzung und Themenschwerpunkte (Objectives and Key Themes)

This thesis aims to investigate the role of shock-cell and Mach disk in generating noise from jet engines. The study focuses on calculating shock-cell spacing and Mach disk dimensions from various C-D nozzle configurations using the Shadowgraph technique, analyzing how these parameters vary with different test conditions.

• The influence of shock-cell and Mach disk on jet engine noise production.
• The use of the Shadowgraph technique to visualize and measure shock-cell structures.
• The impact of various nozzle configurations, temperature ratios, and nozzle pressure ratios on shock-cell spacing.
• The validation of experimental findings with theoretical calculations of shock-cell length.
• The significance of understanding shock-cell noise in addressing noise reduction strategies in jet engines.

Zusammenfassung der Kapitel (Chapter Summaries)

• Introduction: This chapter introduces the problem of jet engine noise, highlighting the importance of understanding shock-cell and Mach disk noise. It also outlines the objectives and scope of the thesis.
• Literature Review: This chapter provides a comprehensive review of existing research on jet noise, particularly focusing on shock-cell and Mach disk noise. It examines previous studies on shock-cell structure, noise generation mechanisms, and the effects of nozzle geometry and operating conditions.
• Experimental Setup: This chapter details the experimental setup used in the study. It describes the Shadowgraph technique, the design of the C-D nozzles, and the instrumentation employed for data acquisition.
• Data Analysis: This chapter explains the process of data analysis, including image processing techniques for quantifying shock-cell spacing from Shadowgraph images. It also describes the methods used to calculate theoretical shock-cell length based on empirical formulas.
• Results and Discussion: This chapter presents and discusses the experimental results obtained from the Shadowgraph studies. It analyzes the impact of temperature ratio, nozzle pressure ratio, and nozzle geometry on shock-cell structure and spacing. It also compares experimental findings with theoretical predictions.

Schlüsselwörter (Keywords)

Jet engine noise, shock-cell, Mach disk, Shadowgraph, C-D nozzle, temperature ratio, nozzle pressure ratio, shock-cell spacing, noise reduction.