ORCID Number

0009-0005-0527-0506

Date of Award

Spring 2026

Access Type

Thesis - Open Access

Degree Name

Master of Science in Aerospace Engineering

Department

Aerospace Engineering

Committee Chair

Surabhi Singh

Committee Chair Email

singhs36@erau.edu

First Committee Member

Luis Ferrer-Vidal

First Committee Member Email

ferrervl@erau.edu

Second Committee Member

Andrew Bustard

Second Committee Member Email

bustarda@erau.edu

College Dean

James W. Gregory

Abstract

Supersonic nozzles operate across a range of flow regimes. While an ideally expanded condition yields optimal thrust, practical propulsion systems rarely operate at this design point due to variations in altitude and engine operating conditions. As a result, nozzles frequently operate in off-design conditions. In overexpanded regime, where the exit pressure is lower than the ambient pressure, shock-induced separation may occur within the divergent section of the nozzle, potentially degrading nozzle performance. Understanding the aerodynamic behavior of nozzles operating under off-design conditions is therefore important for improving propulsion system performance and stability. In particular, direct thrust measurements provide a key metric for evaluating nozzle efficiency and validating theoretical or computational predictions of nozzle performance. This thesis aims to characterize the aerodynamic performance of an asymmetric planar de Laval nozzle operating in overexpanded conditions for different nozzle pressure ratios (NPRs). The nozzle is designed to produce Mach 2.045 flow at a design NPR of 8.39. Off-design conditions are generated by varying the stagnation pressure using a pressure regulator. Nozzle performance is evaluated through direct thrust measurements and wall static pressure data collected along the nozzle surface. The net thrust is obtained by measuring the force exerted by the exhaust jet on a baffle plate positioned at the nozzle exit. The plate is mounted on a linear slider mechanism and compresses a load cell when subjected to jet force. This configuration provides a simple and inexpensive method of thrust measurement suitable for cold-flow laboratory experiments. Compared with floating-type thrust stands, the baffle plate configuration reduces structural complexity and potential measurement uncertainties while allowing rapid testing of different nozzle geometries. Surface pressure measurements are obtained from pressure taps located along the top wall of the nozzle to provide spatial pressure distributions and insight into internal flow features. By varying the nozzle pressure ratio, this study investigates the influence of off-design operating conditions on nozzle performance and internal flow behavior. In addition to supporting research objectives, the thrust measurement facility developed in this work is designed to serve as an instructional experiment for the undergraduate course AE 315 Experimental Aerodynamics at Embry-Riddle Aeronautical University.

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