International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 04 Issue: 07 | July -2017
p-ISSN: 2395-0072
www.irjet.net
COMPARISON OF NOZZLE PRESSURE RATIOS Akhil R,Ashik Shah, Vishnu C A Aeronautical Department, Mount Zion College of Engineering, Kadammanitta, Pathanamthitta, Kerala, India ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - A nozzle is a relatively simple device, just a
specially shaped tube through which hot gases flow. However, the mathematics which describes the operation of the nozzle takes some careful though, nozzles come in a variety of shapes and sizes depending on the mission of the aircraft. Simple turbojets, and turboprops, often have a fixed geometry convergent nozzle as shown on the left of the figure. Turbofan engines often employ a co-annular nozzle as shown at the top left. The core flow exits the center nozzle while the fan flow exits the annular nozzle. Mixing of the two flows provides some thrust enhancement and these nozzles also tend to be quieter than convergent nozzles. Afterburning turbojets and turbofans require a variable geometry convergent-divergent - CD nozzle. In this nozzle, the flow first converges down to the minimum area or throat, and then is expanded through the divergent section to the exit at the right. The flow is subsonic upstream of the throat, but supersonic downstream of the throat. The variable geometry causes these nozzles to be heavier than a fixed geometry nozzle, but variable geometry provides efficient engine operation over a wider airflow range than a simple fixed nozzle. Key Words: ANALYSIS, COMPARISONS, NOZZLE PRESSURE RATIOS, RAMP ANGLE, CONVERGENT-DIVERGENT (CD) NOZZLE
1. INTRODUCTION
|
1.1 Motivation of the work The convergent divergent nozzle at various operating condition (i.e. over expanded conditions) causes the various flow separations occurred in the nozzle. The analysis of the various single expansion ramp nozzles can be carried out to examine the flow behavior.
1.2 Objective
The main objective of this work is to understand the flow by optimizing the geometry of the single expansion ramp nozzles. To investigate the basic flow features inside the nozzle. To investigate the Mach number variation at different NPRs. To investigate the flow separation phenomena in different nozzle configuration and at different NPRs. To identify the efficient operating conditions with respect to the nozzle pressure conditions and the effect of the initial ramp angle.
2. METHODOLOGY
The convergent-divergent (CD) nozzle was introduced in the l950’s in an effort to further increase the Mach number capability of military fighter aircraft. The addition of a divergent section to a convergent nozzle provided further expansion of the flow to supersonic conditions at the nozzle exit; this resulted in an increase in momentum thrust. Convergent divergent nozzles often incorporate variable geometry to maintain high performance over a wide range of flight conditions. The F-4 represented the first proof of concept for the CD nozzle; now CD nozzles are utilized in most supersonic military aircraft. Nozzle design improvements continued throughout the 1960’s and 1970’s with an emphasis on increased installed thrust. The nonaxis-symmetric convergent-divergent nozzle was envisioned late in this period, with prospects of installed performance gains over the axis-symmetric nozzles employed in aircraft such as the F-14 and F-15. As a result of improved nozzle integration with the airframe, the non-axis-symmetric nozzle offers performance gains from a reduction in aft-end drag. Non-axis-symmetric designs also offer the designer © 2017, IRJET
additional freedom to integrate vectoring and reversing hardware into the nozzle.
Impact Factor value: 5.181
|
The objective of this work is to analyze the flow through three different SERN nozzles having different initial ramp angle at different NPRs. In addition, it also compares the performance parameters like actual to ideal thrust ratio, total pressure loss and nozzle efficiency. Furthermore, it also analyzes the effect of initial ramp angle on the pressure plot.
2.1 project methodology
Single Expansion Ramp Nozzle (SERN) has been chosen for computing the flow through the nozzle. Three different SERN nozzles having different initial ramp angle has been considered for analysis. These different nozzle configurations are named as AP1, BP1and CP1. 10 NPR cases are considered for the AP1 nozzle. There are 11 cases are considered for the BP1 nozzle.
ISO 9001:2008 Certified Journal
|
Page 641