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August 2014
The Flow
CFD Insights for the Turbomachinery Designer
INSIGHT: The Role of Advanced Fluid Dynamics Software in Education
In this month’s issue, we focus on the use of CFD software as a learning tool for training the next generation of design engineers.   We spoke with Professor Vincent Capece of the University of Kentucky’s College of Engineering, who agreed to share his recent experience using ADS software in his “Aerodynamics of Turbomachinery” class at the University of Kentucky
FLOW: Can you give us some background on yourself and your experience in both academia and industry?
 I’ve been at the University of Kentucky since 1999. My industrial experience comes from working at Pratt & Whitney in fluid-structure interaction. At the University of Kentucky, my research is mostly in turbomachinery, both experimental and computational. I teach classes in the thermal sciences such as fluid mechanics and gas dynamics.

I am based at the University of Kentucky’s campus at Paducah, rather than our main Lexington campus. We have a large open bay research lab here in Paducah, which has a subsonic wind tunnel, and a low-speed research compressor. Only a handful of universities in the U.S. have a research compressor of this size and quality. At the main Lexington campus there is also a subsonic wind tunnel, with PIV (Particle Image Velocimetry) type capabilities. 
FLOW: Can you describe the turbomachinery class that you teach at the University of Kentucky?
 It is an elective class called “Aerodynamics of Turbomachinery”. It is a basic first class in turbomachinery and I have been teaching it even numbered years for the past few years. The course has been taught seven times. The class is open to both undergraduate and graduate students so we can have a mix of junior to Ph.D. students; there are different expectations for undergraduate and graduate students This last semester, we had about 20 students from both campuses. They were all undergraduate students this time, juniors and seniors.

The class focuses on how to design the shapes of the turbomachinery airfoils for a given performance. I really try to give the students an early exposure to what it’s like to be an aerodynamic design engineer, which I think is quite exciting. Several of my students are interested in pursuing aerospace careers. 

The class is both in-person in Paducah as well as distance-learning for students at the Lexington campus. I am based in Paducah, and I had a teaching assistant, Bradley Butler, to work with students in Lexington.
FLOW: What are the challenges of teaching turbomachinery aerodynamics to students who are new to this field?
 The biggest challenge is that this subject is very multi-disciplinary in nature. Pretty much every mechanical engineering field that you can imagine is in there. But students are used to each class being its own little room – isolated from each other. Unfortunately, this is how many university classes are taught. But engineering isn’t really like that – it’s a continuum. There are no walls between disciplines in real-world engineering. You use everything. We do a review in the beginning of the class, but a lot of the students still struggle with this aspect. I’ve been looking for ways to get the students more engaged with the learning process – how to make it more real for them so they can see how all these different disciplines come together.
FLOW: What kind of experience with CFD did your students have prior to this class?
  From an academic perspective, the students had no training in CFD prior to this class. A few students had some CFD exposure through undergraduate research projects, possibly in internships and the like.
FLOW: Why then did you decide to use ADS’ CFD software for this class? What made you feel that it could be used successfully for such an early stage class on turbomachinery?
   I was really looking for a way to get the students more fully engaged and to help them understand turbomachinery design in a natural way. In previous classes, without the CFD software, the students would be given examples and they would have to manually draw the blade based on the design parameters. This process could take days and humans don’t absorb the material as quickly when such a large disconnect is present. I felt software could really help the students, by enabling them to see what the blade design that they come up with actually looks like, what the resulting pressure contours look like, and then correlating it back to their classroom material. The challenge I faced is that advanced CFD software packages are often difficult to use and take a long time to get up to speed on.

I received a demo of the ADS Foil Designer from the ADS team at the beginning of the semester, and I had used their solver and mesh generator in the past. The advantages of the system were evident even in an early beta version of the software. The interface boils down airfoil design into the basic parameters that can be translated into textbook definitions that our students understand. The mesh generator is completely automated, built specifically for turbomachinery, and integrates nicely with the solver. They execute incredibly fast, with a turnaround time from design to solution in minutes. With that system, I knew I could avoid the difficult and time consuming tasks of building a structured mesh for every new airfoil and setting up the solver for turbomachinery applications.

There were definitely still a lot of unknowns when you introduce anything new into a class, and I knew there was some risk in us being the first beta customer for ADS 6, but I felt the pros outweighed the cons. 
FLOW: You saw the first demo at the beginning of the semester and had it integrated into the class within that same semester. You started this process very quickly, how did that go?
As you can imagine, it was a bit of a challenge to have 20 students across two different locations learning and using the software, especially when it was a beta version! So I started with just four students, Gregorio Robles, Ezra McNichols, Matthew Jehnke, and Caterine Meza, who got early access to the ADS software and started with it about a month into the semester. They got the software up and running on their own machines, used it for several weeks, and then later they were able to mentor the other students. These four students really sped up the process. During those first few weeks, I had weekly meetings with the early-adopter students and gave them various problems to solve using the software. It only took them a few weeks to get comfortable with the software, so then I asked them to create a PowerPoint presentation and a video to help train the other students. These four students did an excellent job, and the process worked well to get everyone else up to speed. There was a lot of interaction and engagement among the students.
About three months into the semester, we had the software installed on three machines in Paducah, on the computer in the teaching assistant’s (Bradley Butler) office in Lexington, and many of the students installed the software on their own personal computers as well; Bradley worked with the students in Lexington for all “hands-on” help that they needed. As it turns out, we had only a minimal amount of problems which was pretty impressive given the diversity of setups, from a cluster to PC’s to a virtual machine on a Mac laptop. We found there was very little support needed from ADS. This really gave the students flexibility in where and how they used the software, and as a result they could use it in a way that adapted to their own particular learning style.
FLOW: How do you feel integrating the software into your class helped the students?
Well, I believe it helped in a few ways. I believe that doing promotes learning. I also believe that peer to peer learning is a great teacher. Lastly, I think introducing advanced software like ADS early on prepares the students for what it will be like in the industry.

I wanted to help the students develop their critical thinking skills, so they can get that “feel” for the right solution that an experienced engineer has. Visualization of the end solution is a big issue – what does a transonic pressure blade or a compressor blade actually look like, and why are the shapes different? Even when the students have all of the parameters – the angle coming into the blade, the angle going out – they still don’t really know what the design actually looks like. That’s where the ADS software really helps. The students can put in the design parameters they’ve come up with, and they can construct the blade right on their screen and see it. Then, with the ADS integrated workflow, they can compute the flow for that blade using Code Leo and Code Wand. Because it runs so fast, and the students can use it on their own laptops, they can look at it and ask what-if questions: what if I change the leading edge radius? How does that affect the pressure distribution? I think this really helps with their critical thinking. By using the software and seeing the simulations, they are learning much more clearly and completely, and it helps to close the learning loop for some students.

I think that using the CFD software the students can develop that “feel” for the solution that normally comes with experience. Of course, I don’t expect that it will ever replace that experience, but the goal is for this to help them develop their own critical thinking skills and start to think like an engineer.
FLOW: Now that the semester is completed, do you feel the integration of ADS into your class was worth the risk?
Definitely. The students have told me that by using the software they have been able to look at their solution and try different things. It has helped them explore more complex systems in a self-directed way, rather than just doing paper-and-pencil over-simplified homework problems. One of my students said “it was very useful to have the case examples, and then having the ability to modify the case really helped with learning.” The software reinforces the theory that they’re studying in the class; for example, another student told me “the software was really helpful to better understand some of the aerodynamic theory.”
FLOW: Have the students used what they learned in your class in other projects?
A few students approached me to do summer projects. So I set up two teams to work on a couple of back-burner research projects that I had. One group is doing some more detailed calculations on the class project to redesign our research compressor. The other team is making some different tweaks by changing the shape of the stator span wise and doing a design around that. Then we will be able to compare the results. In addition to that, one of the students wanted to work on splitter blades, so he’s using the software to work on the Wennerstrom rotor.
This is more interest than I usually have for summer projects, and I think the software has really got them excited. They can probably use the software better than I can now!
FLOW: If you use the software again, what will you do differently next time?
We will definitely use the software again. We always do a different project in the class, so next time it will be a turbine. I’d like to get the whole class engaged earlier in the semester with the software. Since we now have all the videos that the students made, they can start using it right away. I’m really excited about being able to integrate the software more into the classroom and make it a core part of the learning process. I found that the software enables peer-to-peer interaction and self-exploration that really promotes learning for these students. I plan on using the software in a cohesive way with the lesson plan starting the first month of the class.
What I have found with using the ADS software in this class is that it not only helped to reinforce the class curriculum in a much more interactive way, but more importantly, it can fundamentally change the way that I engage my students, and the way that they learn. Every student has a different learning style, and requires a different way to really engage them. Since the software is so inherently interactive, it lets each student close the learning loop in ways that are best for them. They can ask questions, get answers, and learn from that to ask other questions. I truly believe this can open doors into new ways to teach engineering to a much broader base of students than we could reach before. I think this is the most exciting aspect of what we are doing in this class at the University of Kentucky, and I hope that we can really make a difference to these students.
FLOW: Thanks for your time, Vince.
Your welcome.
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CASE STUDY: Introduction to ADS for Students by Students
Students in the University of Kentucky Aerodynamics of Turbomachinery class produced a presentation and a video to help other students get up to speed more quickly.  Take a look at the presentation <here> and the video <here>
NEWS: Webinar - Tips for CFD Analysis of Volutes 
Join us Wednesday August 27th for a free webinar in partnership with Pointwise Inc.  In this webinar, we evaluate a generic volute design. Simulations were performed using Code Leo, a computational fluid dynamics (CFD) solver developed by AeroDynamic Solutions (ADS), on three different grid types generated with Pointwise: multi-block structured, unstructured with a hexahedral boundary layer, and unstructured with a prismatic boundary layer. We will describe the process for generating each grid, and discuss their relative pros and cons regarding meshing time and ease of modification. In addition, we will evaluate the numerical solutions from each of the three mesh topologies for accuracy and overall solution turnaround time.<more>
NEWS: ADS to Present at TETS 2014
ADS will be presenting two papers at the Turbine Engine Technology Symposium 2014 conference September 8th through the 11th in Dayton, OH.  <more>
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