The phrase "a number of prototypes" is correct and usable in written English.
It can be used when referring to multiple prototypes that have been created or developed for a project or product.
Example: "The team has created a number of prototypes to test different design concepts before finalizing the product."
Alternatives: "several prototypes" or "multiple prototypes".
He built a number of prototypes, but none of his ideas had that indefinable frisson required of a smash hit.
At the Microsoft Research Silicon Valley Road Show, the company demonstrated a number of prototypes designed to work with Microsoft's online mapping application, Windows Live Local.
A number of prototypes of the stent graft, which are the same size as standard oesophageal and aortal stent grafts, have been produced successfully.
A number of prototypes have been developed and the final version is expected at the end of the 3-year project.
After the simulation, a number of prototypes were fabricated and tested to measure the real power output and verify the simulated results.
Prototype classifiers are a type of pattern classifiers, whereby a number of prototypes are designed for each class so as they act as representatives of the patterns of the class.
A thorough experimental analysis was performed on a number of prototype condenser designs.
A number of prototype gimbals were manufactured using a new process of a closed mould technique, with expanding silicone inserts and a pre-impregnated carbon fibre/epoxy resin woven material.
The company distributed a number of prototype iPhone cases to journalists and "customers" and might commercialize the product later this year.
A number of prototype reactors of different configurations were first constructed in an effort to incorporate the lessons learned into larger scale reactors.
First, a number of prototype devices were built, consisting of four major components: a RM-090 sensor board [17], an airlink fastrack xtend GPS-enabled GPRS modem [18], a battery pack, and a door sensor.
