Review of Reduced-Order Models for Homogeneous CO2 Nucleation in Supersonic and Hypersonic Expansion Flows

Several classical and non-classical reduced-order nucleation rate models are presented and compared to experimental values for the homogeneous nucleation rate of CO2 in supersonic nozzles. The most accurate models are identified and are used in simulations of a condensing supersonic expansion flow. Experimental results for the condensation onset point of CO2 in a variety of expansion facilities are presented and compared to simulations and to new data acquired at the SBR-50 facility at the University of Notre Dame.

Performance Trends For Aerospikes & Supersonic Nozzles With Center-Bodies

The aim of this report is to examine performance trends for Aerospikes and Supersonic nozzles with center – bodies. The initial case that was tested is a convergent – divergent conical nozzle with a geometry and inlet flow conditions obtained from a NASA technical note. The technical note mentions that air was used as the working fluid for the nozzle. This case served as the base case for comparison with the performance of later nozzle designs. Nozzle flow for all the cases that were tested was simulated using ANSYS Fluent, for ambient conditions at 20km standard atmosphere. The convergent – divergent conical nozzle has the following calculated performance parameters using results from ANSYS Fluent: mass flow rate of 9.660 kg/s, axial Thrust of 10,583.5 N, and a specific impulse of 111.7s. All of the Supersonic nozzles with center – bodies have calculated specific impulse values lower than 111.7s by 0.4 – 1.6s, for approximately the same calculated mass flow rates as the base case. Adding a center – body to the original conical nozzle, was simply detrimental to performance. With regards to the Aerospike nozzles, 18 of them were tested. Aerospike 18 has the highest calculated specific impulse, at 115.3s for a calculated mass flow rate of 9.671kg/s. Aerospike 13 came in second at 114.6s, for a calculated mass flow rate of 9.676 kg/s. Several of the Aerospike designs did not out-perform the base case in terms of specific impulse. For those Aerospikes, the convergent – divergent section had a significantly lower thrust than the base case and the center – body was not able to over-compensate for the lower thrust. This report also looks at trends in thrust contribution by the convergent – divergent sections and center – bodies of Aerospikes at different nozzle geometries. The working fluid for all the cases tested in ANSYS Fluent including the base case, is air at a ratio of specific heats equal to 1.4.

Performance Trends For Aerospikes & Supersonic Nozzles With Center-Bodies

The aim of this report is to examine performance trends for Aerospikes and Supersonic nozzles with center – bodies. The initial case that was tested is a convergent – divergent conical nozzle with a geometry and inlet flow conditions obtained from a NASA technical note. The technical note mentions that air was used as the working fluid for the nozzle. This case served as the base case for comparison with the performance of later nozzle designs. Nozzle flow for all the cases that were tested was simulated using ANSYS Fluent, for ambient conditions at 20km standard atmosphere. The convergent – divergent conical nozzle has the following calculated performance parameters using results from ANSYS Fluent: mass flow rate of 9.660 kg/s, axial Thrust of 10,583.5 N, and a specific impulse of 111.7s. All of the Supersonic nozzles with center – bodies have calculated specific impulse values lower than 111.7s by 0.4 – 1.6s, for approximately the same calculated mass flow rates as the base case. Adding a center – body to the original conical nozzle, was simply detrimental to performance. With regards to the Aerospike nozzles, 18 of them were tested. Aerospike 18 has the highest calculated specific impulse, at 115.3s for a calculated mass flow rate of 9.671kg/s. Aerospike 13 came in second at 114.6s, for a calculated mass flow rate of 9.676 kg/s. Several of the Aerospike designs did not out-perform the base case in terms of specific impulse. For those Aerospikes, the convergent – divergent section had a significantly lower thrust than the base case and the center – body was not able to over-compensate for the lower thrust. This report also looks at trends in thrust contribution by the convergent – divergent sections and center – bodies of Aerospikes at different nozzle geometries. The working fluid for all the cases tested in ANSYS Fluent including the base case, is air at a ratio of specific heats equal to 1.4.

Homogeneous nucleation of carbon dioxide in supersonic nozzles II: molecular dynamics simulations and properties of nucleating clusters

Molecular dynamics simulations reveal the structural and energetic properties of carbon dioxide clusters nucleating in the gas phase at extreme undercooling.

A Simple Method for the Design of Supersonic Nozzles of Arbitrary Cross Section Shape

A simple approach for the design of supersonic nozzles of complex 3D shapes is presented. The Method of characteristics is primarily applied to compute the axisymmetric flow field of the supersonic section of the de-Laval nozzle. Two-dimensional simulations are performed for the axisymmetric flow fields. The 3D configuration is then generated from the desired exit axisymmetric cross-sectional shape chosen through tracing its geometrical parameters back.to the throat. Elliptical, corrugated and two-dimensional wedge nozzles were designed using this approach. Preliminary results show a smooth geometrical transition from the throat to the exit cross section. Further three-dimensional analyses of the obtained geometries along with cold flow testing constitute the next steps to be performed.