Smarter Munitions

The Engineer

Mehul Patel is the Director of Aerodynamics Group at Cleveland-based Orbital Research Inc. (ORI). ORI designs, develops and commercializes custom-engineered solutions in the area of aerodynamics, MEMS, and advanced controls for the U.S. military and industry partners. Mr. Patel's group is active in a wide variety of efforts focused on the development of advanced aerodynamic control systems for aircraft and munitions.

Smart Skin for Munitions

Among the Aerodynamics Group’s most successful R&D programs is hingeless Smart Skin for munition flight control. Working closely with the U.S. Air Force Research Laboratory (AFRL) and the U.S. Army Research Development and Engineering Command Armament, Research, Development and Engineering Center (RDECOM-ARDEC), the ORI team has developed unique, custom-engineered munition control systems using state-of-the-art flow control actuators and algorithms that improve munition range, control, and maneuverability.

While working on the Munition Smart Skin program, Patel’s group discovered that traditional hinged control surfaces impose significant limitations on munition performance. On the other hand, hingeless control surfaces integrated with miniature flow control actuators expand overall munition performance and payload by shaving off considerable weight from motors traditionally used to guide fin surfaces.

This innovative, low-cost alternative for maneuvering munitions called Munition Smart Skin contains an embedded system of miniature sensors on a projectile's outer surface and actuators, as well as a real-time feedback controller just below the surface. The outer layer of skin is perforated with miniature slits. Using embedded MEMS structures, a miniature-spoiler is pushed through the slit to induce a small physical change on the fin, nose, or the tail, which creates a large effect on the region's flow field. This forces an overall change in pressure distribution around a significant portion of the surface, and pitch, roll, or yaw adjustments can be made in real time.

Smart Skin can also be thought of as virtual shaping; meaning that a fin or wing has the ability to change its shape and the flow field without an actual deflection of a flap, slat, or aileron—all of which is unseen from the exterior. This system can be transparent to the munition navigation system and can be operated autonomously by a ground- or air-based pilot, or by an onboard guidance system.

Simulation and Testing

To validate their research findings and test active flow control system prototypes, ORI’s Aerodynamics Group relies heavily on low- and high-speed wind tunnel experiments, CFD simulations, and 6-DOF flight modeling. For CFD studies, Patel’s group uses the WIND-US code, a 3-D Navier-Stokes flow solver developed by the merger of three CFD codes (NASTD, NPARC, and NXAIR). Mr. Patel works closely with Dr. Alan Cain, President of Innovative Technology Applications Company L.L.C., through all CFD pre- and post-processing stages.

“By combining CFD analysis with wind tunnel experiments,” Patel explained, “we are able to reduce the total turnaround time for feasibility studies as well as systems development. This time-saving results in an overall lower cost for our customers, and ultimately the U.S. taxpayer.”

Plotting and Data Visualization

Because his group frequently employs CFD simulations, Patel knew it was imperative to find a high-quality CFD post-processing tool that was both cost-effective and reliable. When he discovered Tecplot and coupled it with its CFD Analyzer add-on, Patel said he has found the "perfect solution".

“I was looking for an extensive, yet not-too-expensive, data plotting software package, primarily for post-processing of CFD data,” Patel said. “After learning more about the capabilities of Tecplot and its add-on tool, CFD Analyzer, which lets user calculate variables and extract critical information from the data set, it seemed an obvious pick for our data processing needs.”

Patel is currently using Tecplot to look at large, 3-D data sets (typically between 1 to 2 million grid points), which are in a multi-zone format. “Tecplot allows me to work on a specific group of zones [by turning off other zones] to achieve a high-level of resolution in analyzing complex data in small regions of the computational domain,” he said. “Furthermore, it enables me to automate complete 2- and 3-D flow analysis using macros."

The Tecplot features most commonly used by Patel are 2-D slices, contour plotting, streamtraces, and the CFD Analyzer add-on. “These features are important to anyone doing CFD post-processing, and I find myself calling upon them on a daily basis,” he said.

When asked to list Tecplot’s three greatest strengths as it relates to his work, Patel started with the obvious. “The software’s ease-of-use is exceptional,” he said. “It’s a breeze to import and export files, plot data in a multitude of ways, create custom-configurations, and make videos and animations in the file format of my choice.”

Beyond ease-of-use, Patel cited the CFD Analyzer and Tecplot, Inc.’s “excellent” technical support as key strengths of the product. “I haven’t had to seek out technical assistance with any great regularity, but when I have called Tecplot’s technical support group, I found knowledgeable people who were truly interested in solving my problem.”

All images and descriptions copyright © by Orbital Research Inc. All rights reserved. Copyright © 2005.