Investigating the Formation of Ice Crystal Aggregates and Their Impacts on Hypersonic Vehicles
Abstract
Hypersonic vehicles inevitably encounter frozen droplets, ice crystals, and ice aggregates on their flight paths through high-altitude clouds, which can significantly damage their airframes. The objective of this research is to characterize atmospheric ice particles and ice crystal aggregates (joined clusters of individual particles) that are abundant in cirrus clouds (4-20 km) and potentially present in other high-altitude clouds (e.g., polar stratospheric clouds up to 25 km, and noctilucent clouds up to 85 km), allowingimprovements in understanding their aerodynamic interactions with flow features characteristic of hypersonic vehicles, including shock waves and boundary layers. Individual ice particles# and ice aggregates# size, mass, and behavior in relation to the severe thermodynamic changes in shock waves directly correlate to their damage potential when encountering a hypersonic vehicle. If impacts on airframes can be quantified, then more accurate models of damage potential will be possible; yet currently, there is a lack of ground-based techniques to introduce well-characterized ice particles into flow fields in a controlled manner and to test whether ice aggregates impact as a single large particle or disintegrate into clusters of monomers when traversing a vehicle#s shockwave. The proposed research will achieve such tests by bridging scientific techniques: ice particles will first be grown and characterized in a microparticle levitation platform, then they will be introduced into high-speed flow fields for imaging and analysis. This research will utilize a catalog of a recent field campaign#s high-resolution images of ice crystal particles and aggregates as references, as part of the Navy sponsored CapeEx19 field project. The images clearly show local monomer joints that are very small compared to the monomer#s size, suggesting possible dissociation points. This ONR YIP project will be achieved through the following three Objectives:Objective 1: Trap and levitate frozen microdroplets: A low-temperature platform will be developed for growing, trapping, and levitating individual ice microparticles. A dual electrodynamic balance will enable colliding individual crystals together under controlledtemperature and humidity and identifying optimal thermodynamic conditions for aggregation. This technique will allow identificationof optimal testing conditions for ice crystal growth in situ and simulation of large ice crystal chain-like aggregation. The effects of temperature and relative humidity on aggregate formation and structure will be determined. Direct observation of shock waves changing the aggregates# structures will then be possible. Objective 2: Introduce the ice particles to shock waves: The ice crystals from Objective 1 will be imaged and introduced into Purdue#s 3-inch shock tube to examine their demolishment in a shock wave and determine where breakup occurs in the aggregate. This knowledge will then be applied to experiments on injecting ice crystals into Purdue#s light gas gun facilities initially, then progressing to Southwest Research Institute#s light gas guns. These series of tests will yield information needed to determine which portions of a hypersonic trajectory are most likely to be affected by ice particle formation.Objective 3: Interface with experts performing related studies: This ONR YIP project will leverage experimental techniques atUND, Purdue, and SwRI, as well as existing flight observations from the ONR sponsored CapeEx19, to create comprehensive data on icecrystal interactions with supersonic and hypersonic flow fields for comparison to and validation of theoretical work. This project will also extend the current work of an active MURI team, which focuses on particulate and droplet effects on hypersonic flight, butnot on ice crystals and their aggregates. Therefore, the proposed work will be readily applicable to current high-speed flow theoretical work.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 03, 2023
- Source ID
- N000142312269
Entities
People
- Hallie Chelmo
Organizations
- Office of Naval Research
- United States Navy
- University of North Dakota