I have previously covered some of the analysis used to design the throat section of the wind tunnel, this time I shall cover some of the design used for the rest of the tunnel design. The idea was to use a pressure vessel coupled to a large diameter ball valve, so that large volumes of... Continue Reading →
Ramjet Part 3 – Intake Geometry & Shock Waves
The intake design is arguably the most critical feature of the ramjet; jet engines can rely upon the compressor to raise the pressure of the air, while pulse-jet engines can utilise the pressure waves from each previous cycle to compress a fresh fuel-air charge. But a ramjet can only rely on the compression produced by... Continue Reading →
Ramjet Part 2 – Engine Cycle and Thrust
I have finally figured out that WordPress supports LaTeX, so that makes putting in endless streams of equations much easier! The ideal ramjet engine operates on a Brayton Cycle which is characterised by constant pressure combustion followed by expansion of the combustion products to near ambient pressures. The enthalpy-entropy diagram for this engine cycle is... Continue Reading →
Ramjet Part 1
The basis for all the rocketry and wind tunnel posts discussed previously are primarily for the development of a micro-ramjet engine. For now I have gone as far as I can on the supersonic wind tunnel and the design has more or less been finalised, all the tunnel wall contours for the test sections are... Continue Reading →
Supersonic Wind Tunnel Part 2 – Initial Nozzle Design
The most critical part of the wind tunnel is the nozzle, it must accelerate the flow to the desired Mach number while leaving the test section free of shock waves. The two methods I have used have been a numerical technique to create the geometry and later on I'll use computational fluid dynamics (CFD) to... Continue Reading →
Supersonic Wind Tunnel part 1
Previously I had mentioned the use of water flow to simulate supersonic flow, however after having done some research I've abandoned this approach for now in favour of building a supersonic wind tunnel. The main reason for this is I'd like to some investigation on combustion stability at the small scale I want to operate... Continue Reading →
Now for something completely different…
So the reason I've been messing around with rocket motor design lately is that an old idea I started dabbling in several years ago, that of a truly miniature ramjet, something that could fit in the palm of your hand. I have read a report on a tiny ramjet designed to operate at Mach 4, however I'm... Continue Reading →
Solid Fuel Regression Part 2..
So in this second of my posts on solid fuel grain regression I'll cover more complex grain core shapes, although the process is not overly dissimilar to the methods discussed previously. An average web length is found and an incremental distance is then defined, this distance is then used to regress each point of the... Continue Reading →
Solid Fuel Regression Part 1
In the first of a series on the modelling of rocket motors I'm going to cover the aspects of the design of the solid propellent grain, which is the hardened mass of combustible propellent within the motor itself. Solid fuel rocket motors range from the model rocket motors produced by the likes of Estes with their... Continue Reading →