Create the Future?

Create the Future Design Contest 2014

 

Since 2002, NASA Tech Briefs has been stimulating and rewarding engineering innovation through the Create the Future Design Contest. During that time, the annual event has attracted more than 8,000 product design ideas from engineers, entrepreneurs, and students worldwide. And in recent years, it has attracted us, with Jeff serving as one of the judges in 2010, 2012 & 2013.

 

Even though it is still January, and Create the Future doesn’t officially open for entries until March 1st, we believe it is never too early to remind you and encourage you to participate. Categories include:

  • Aerospace & Defense — Product innovations with applications in the aerospace, aviation, and/or defense markets.
  • Consumer Products — Products that increase quality of life in the workplace, at home, during leisure time, or while traveling.
  • Electronics — Products that improve computing, communications, and other fields that rely on advances in electronic components and systems.
  • Machinery and Equipment — Products that speed and improve work, manufacturing, or scientific research processes.
  • Medical Products — Products that improve the efficiency and quality of healthcare.
  • Safety and Security — Products that enhance the security or safety of individuals, businesses, communities, or nations.
  • Sustainable Technologies — Products that help reduce dependence on non-renewable energy resources, as well as products designed for other purposes using environmentally friendly materials or manufacturing processes.
  • Transportation & Automotive — Products that enable movement of people and goods from one place to another.

For a full list of last year’s winners, and sponsors, and to learn more about how the contest works, visit them Create the Future website at www.createthefuturecontest.com. You just might see something that inspires you. One of the things we like to point out is that our good friends over at COMSOL are Sponsors, along with SAE International™. They just keep on serving.

COMSOL Training

COMSOL Training – The Truth About Our Classes

We readily accept that our COMSOL Training classes are not for everyone, especially with COMSOL doing such a good job.  The training calendar is put together for the first half of the year, and we are taking signups now for our classes next month. Check it out using this link. But some people may wonder why an organization like ours would continue to offer these classes? One simple reason…

 

We want to see more and more people grow their use of COMSOL to a level of mastery; especially those people who are committed to developing tomorrow’s innovative technology solutions today!

Our COMSOL Training enables students to be leaders in solving problems with COMSOL Multiphysics

Our COMSOL Training enables students to be leaders in solving problems with COMSOL Multiphysics

With this in mind, we have decided to share the truth about our classes, in a rather unique way. Here is a list of The TOP Eleven reasons NOT to enroll in one of the AltaSim COMSOL Training classes:

 

  1. All training should be easy and I shouldn’t have to work very hard to master COMSOL.
  2. It’s just a piece of software; I’m sure there’s a manual I can read if I get stuck.
  3. I never really wanted to be that well-versed in knowing how to use software to create & innovate new technologies.
  4. I prefer to keep all my learning at 30,000’ and avoid the details.
  5. I only want to achieve a “casual-user” level of expertise while I am developing products that could save lives and make money.
  6. I would hate to learn from people who use it every day in real life situations to solve unbelievably complex problems from all over the world.
  7. I only use it occasionally so I don’t need it to work properly.
  8. I am fully conversant with all the nuances, functionality and operation of all the modules.
  9. My problems always solve quickly and correctly the first time.
  10. I have someone in my office who uses COMSOL so I can always bounce ideas off them.
  11. I don’t want to solve problems, just identify that they are there.

We do not provide a 30,000’ view. Instead, we tunnel deep into the everyday use of COMSOL. We are not looking to train the casual user – rather, we are looking to train those who want to master the functionality in COMSOL to maximize its effectiveness. We are not selling COMSOL, but if we could we would. We use COMSOL daily to solve a wide range of problems from CFD to Structural, from Plasma to Heat Transfer, from Electromagnetics to Acoustics and single physics to problems with more physics than we have fingers and toes. We have shown that COMSOL can address problems previously considered intractable and provide insight, guidance and knowledge to help new technologies reach the market place. This is why we continue to schedule COMSOL Training classes.

 

If you find this hard to believe, you are not alone. It shocked us too! We didn’t realize we were this passionate about offering COMSOL training classes until we started to pay attention to some of the feedback from our students. Of course we can’t share details of what they are working on but we can share the range of projects that people sitting in our intimate classroom are using COMSOL to address, a list that is too long to list exhaustively but has included:

  • CFD of both single and multiphase flow
  • Electromagnetic radiation
  • Structural-Thermal deformation
  • Photonics
  • MEMS technology
  • Electromagnetics
  • Geophysics
  •  Plasma

 

And we can share that these students have come from:

  1. The United States
  • East coast, west cost and all the bits in between including Columbus, Ohio
  1. Canada
  2. Saudi Arabia
  3. Norway
  4. Trinidad and Tobago
  5. Mexico

 

With 12 seats and multiple instructors, we realize that this may be way too much personal attention for most engineers. We’ve almost had to apologize for that too, but what can we say… We’re crazy about wanting to see people master COMSOL! But don’t blame us… blame the good folks at COMSOL for developing such a powerful tool.

 

 

Ceramic Matrix Composites

Ceramic Matrix Composites: Background

Ceramic Matrix Composites Part

We are often asked “What do you mean by fully coupled multiphysics simulations?” By way of answering this question we are providing a series of Blog articles that will explain the background to a fully coupled multiphysics simulation using a direct example on simulating the processing of ceramic matrix composites (CMC), advanced materials for use in next generation aero-engine applications. To provide some context here is some background about CMCs and the problems faced in their manufacture.

Conventional materials such as nickel based superalloys, titanium, aluminum, and steel are being used within 50 degrees of their melting point during engine operation, to increase power density they need to be replaced by materials capable of operating at temperatures approaching 2000F. Ceramics and CMCs can withstand these temperatures and use in hot engine parts will:

  • improve thrust and fuel efficiency while reducing emissions
  • reduce cooling requirements
  • simplify component design, and
  • reduce weight of the supporting structure

The relatively low fracture resistance of ceramics relative to metals, however, restricts their extensive use as structural elements in turbines. To address this challenge, significant research has focused on the development of CMCs that contain a mixture of a ceramic matrix and ceramic fibers to increase structural durability without compromising high temperature capabilities. Currently, CMCs have been considered in applications that support moderate loads e.g., nozzles, combustion liners, airfoils and exhaust components but are planned for operation in more critical components such as turbine blades. For these applications, the development and manufacturing costs of high integrity CMCs must be reduced significantly to provide a cost effective option.

Currently two methods are available to manufacture silicon carbide based CMCs:

  1. Reactive Melt Infiltration (RMI)
  2. Chemical Vapor Infusion (CVI)

Reactive melt infiltration (RMI) provides relatively rapid production of near-net shape parts. Chemical vapor infusion (CVI), has many similarities to RMI however, the difficulties in controlling CVI typically generate higher scrap rates than RMI. In addition, CVI typically requires significantly longer manufacturing times than RMI (days as opposed to hours).

In RMI a pre-form of the final desired shape is first manufactured from a porous media. Liquid infiltrates the pre-form through capillary action and simultaneously a chemical reaction occurs between the liquid and pre-form. These reactions often occur within minutes of the liquid contacting the pre-form and the final product takes the shape of the initial pre-form with full density and, ideally, no porosity. Due to the complexity of the manufacturing procedures for CMCs, limited guidelines exist that can readily transfer between different components, shapes and materials. Consequently designers are reliant on expensive and time consuming experimental approaches to develop detailed manufacturing procedures; the impact of these approaches can be significantly reduced by using predictive physics based modeling tools. However, accurate simulation of the RMI process represents a significant challenge: the range of physical phenomena in an analysis is large and not generally available in many commercial simulation tools. An accurate analysis of the RMI process must include the following:

  • Unsaturated flow of fluid into a ceramic matrix
  • Capillary fluid flow
  • Chemical reaction between the fluid and the ceramic matrix
  • Volumetric changes associated with the fluid-solid reaction
  • Temperature changes associated with the fluid-solid reaction
  • Residual stress development
  • Distortion of components

Practical difficulties arise in simulating the RMI process due to the complex interactions and interdependencies between the multiple physical phenomena. For example, fluid flow, material deformation and many of the physical constants are temperature dependent, and the liquid to solid transition and solid state phase changes release latent heat. Thus, any simulation must be capable of analyzing these phenomena simultaneously – a fully coupled multiphysics simulation. To do this successfully one must have expertise in the individual physics but also the implementation of them in any computational analysis. Future blogs will discuss how to analyze these phenomena and integrate them into a single analytical framework.

Heat Sink Design

Heat Sink Design

 

In last month’s Blog we discussed alternative techniques for increasing the amount of heat dissipation in electronic circuits and components. One of the most commonly used approaches to increase heat dissipation is the use of heat sinks. Heat sink design seeks to maximize the surface area in contact with the surrounding cooling medium, generally air in these applications, and is attached using thermal interface materials that have high thermal conductivity and fill the air gap between the component and the heat sink. Air velocity, direction of flow, choice of material, protrusion design and surface treatment are all factors that affect the performance of a heat sink. Heat sink design can take many forms:

  1. Plate-fins: A series of plates or sheets run along the entire length of the attachment area
  2. Pin-fins: Pins are arranged in a regular array and extend
  3. Flared plate fins: A series of non-parallel plates that run along the entire length of the attachment area

In this Blog we address heat sink design and provide guidelines for developing an optimum design for the case of natural convection.

 

A heat sink transfers thermal energy from a higher temperature device to a surrounding fluid medium which is generally air but could also be water, oil or a refrigerant depending on the application, for the purposes of the applications of interest here we will consider the fluid to be air. Thermal dissipation through the heat sink occurs by a conjugate heat transfer mechanism in which transfer of thermal energy occurs by a combination of conduction through the heat sink and into the fluid, convection of the surrounding fluid and radiation into the environment. In most situations, heat transfer across the interface between the solid surface and the coolant air is the least efficient within the system, and the solid-air interface represents the greatest barrier for heat dissipation, a heat sink lowers this barrier mainly by increasing the surface area that is in direct contact with the coolant.

 

Natural convection arises because the hot air has a lower density and thus rises under the buoyancy forces created. This flow can be represented by the dimensionless Grashof number, Gr, that represents the ratio of the buoyancy force to the viscous force acting on the fluid and is given by:

 

Gr        ~ Buoyancy force / Viscous forces

= g.β.(Ts-T).δ3 / ν2                 (1)

 

Where g is the gravitational acceleration (ms-2), β is the coefficient of volume expansion (1/K), Ts is the surface temperature (K), T is the ambient temperature (K), δ is the characteristic length of the geometry (m), and ν is the kinematic viscosity of the fluid (m2s-1). For vertical plates values of Gr > ~ 109 flow is turbulent.

 

Heat transfer into the fluid can be characterized by the Prandtl number, Pr, momentum diffusivity to thermal diffusivity:

Pr         = viscous diffusion rate / thermal diffusion rate

= (cp.µ) / k                               (2)

Where cp is the specific heat capacity (J/kg.K), µ is the dynamic viscosity (Pa.s) and k is thermal conductivity (W/m.K). The Prandtl number controls the relative thickness of the momentum and thermal boundary layers and is often tabulated with other fluid properties, for air and many other gases it is considered that Pr ranges between 0.7 and 0.8. When heat conduction is effective compared to convection: thermal diffusivity is dominant. When convection is effective in transferring energy from an area, compared to pure conduction: momentum diffusivity is dominant.

 

The optimum heat sink design is a balance of maximizing surface area while at the same time setting the spacing of the fines to allow maximum air flow and minimizing friction. Thus heat sinks with closely spaced fins are not suitable for natural convection. The optimum fin spacing for a vertical heat sink is given by:

Sopt = 2.714 (L/Ra1/4)                            (3)

Where L is the characteristic length and Ra is the Reynolds number.

 

The heat transfer coefficient for the optimum spacing is given by:

H = 1.31 (k/Sopt)                                   (4)

Consider the following example: A vertical surface at 80°C is to be cooled by a heat sink in air at an ambient temperature of 20°C. The plate has a width of 20 cm and a height of 30cm, the fins of the heat exchanger are 1mm thick, 30cm long and have a height of 10mm.

Geometry for Heat Sink Design

 

The average temperature of the air on the surface of the fin is 50°C: at this temperature the thermal conductivity, k, is 0.0279 W/m.K, the kinematic viscosity, ν, is 1.82 x 10-5 m2/s, Pr is 0.709 and assuming ideal gas behavior the coefficient of volume expansion, β, is 1/(Ts+T)/2) = 3.1 x 10-3. The characteristic length , L, is the length of the fin thus the Reynold’s number, Ra, is given by:

Ra        = Gr.Pr

 

The optimum spacing Sopt is then determined by equation 3 to be 8.03mm. For a fin thickness of 1mm the number of fins on the heat exchanger is ~22. The heat transfer coefficient can be calculated using equation 4 to be 4.54 W/m.K.

 

 

 

Widgets, Plug Ins and Social Media

Widgets, Plug Ins and Social Media

company

(All the way) Back in 2013, we decided to rebuild our website. We had previously evaluated our site in light of Our Mission and Values and decided we could make some improvements. So we got some new widgets, and some new plug ins, and all the other bells and whistles that come with a new site, and off we went.  Since we “harness tomorrow’s technology to enable our customers to capture today’s markets” it only made since that we figured out better ways to communicate. From our vantage point, we were a group of engineering analysts trying to be more sociable.

 

There are three major commitments we take out of our Mission:

 

  1. Provide lasting value to our customers
  2. Apply technology to enhance the capabilities of our customers
  3. Continue to make an ongoing technical contribution to society

 

That means going forward in 2014 we will be using our website and all of our other Social Media outlets (Facebook, LinkedIn, Twitter) to communicate the heart of what we do here at AltaSim Technologies. If we do this correctly, it will not take on the appearance of self-promotion but rather, serving our customers and our communities. Along the way, if you see anything that you believe would help others whom you know, feel free to share it with them using the easiest means available.

 

Our articles and blogs automatically populate to Facebook and Twitter. This is so readers can easily access and share as they desire. For example, if you are reading this from our Blog, you will see at the bottom of this post a pink “Share” button. This allows you to share our content quickly and easily with your Social Networks. In this manner, all of us get to participate in helping others grow, while making the commitment to grow ourselves.

 

https://www.facebook.com/AltaSimTechnologies

https://twitter.com/AltaSim

http://www.linkedin.com/company/altasim-technologies-llc

 

We are excited about a technologically-advanced 2014 that sees our customers’ enhanced capabilities make huge contributions to society! As always, your comments and dialogue are welcome and desired on the topics we share. Until then, let’s go harness tomorrow’s technology today.